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+{"metadata":{"id":"08c4f51e6fe388eb4d03a093bfeb6862","source":"gardian_index","url":"https://cgspace.cgiar.org/rest/bitstreams/2630e302-f895-4cba-9d92-79a4f5400b1e/retrieve"},"pageCount":172,"title":"Acridid Control Treatments","keywords":[],"chapters":[{"head":"Contents","index":1,"paragraphs":[]},{"head":"Introduction","index":2,"paragraphs":[]},{"head":"Spraying Principles","index":3,"paragraphs":[{"index":1,"size":89,"text":"Apart from emergency situations in which the International Community plays an active role, locust and grasshopper control should be organised at local and national levels. Furthermore, management at the regional level is appropriate for countries which are likely to be affected by perennial outbreaks. At the time of the 1987-1989 Desert locust plague, large amounts of insecticides were sprayed on millions of hectares. The impact on the environment of such large scale applications is significant and therefore appropriate application techniques to minimise adverse effects and maximise control are critical."},{"index":2,"size":96,"text":"Under these circumstances, applications of insecticides in locust control should be undertaken under optimal conditions of efficacy. That requires a multi-disciplinary approach, which combines entomology application techniques and socio-economics, together with the need to preserve the environment. The range of locust control operations, from individual farmer intervention to the use of aircraft, should also be considered. Of course it is imperative to prevent upsurges by controlling large scale locust outbreaks but that should not be done at any cost. It is essential to maximize the efficacy of the pesticides to reduce the quantity required for control."},{"index":3,"size":16,"text":"From this point of view, enhancing and improving application techniques becomes an economic and environmental necessity."},{"index":4,"size":135,"text":"Most of the documents and practical books devoted to locust control deal mainly with insecticides. There are a few which show how pesticides should be applied. It is obvious that good results cannot be expected if a product is spread with a watering can, because the active ingredient must be uniformly distributed on the whole area to be protected. It is however less apparent that a wide droplet spectrum spray can be equally wasteful. Very small droplets can drift far from the target (exodrift) and large drops will tend to fall directly on the soil (endodrift). Both have a negative effect on the environment and do not accurately target the locust pest itself. Therefore it is essential to understand the application process in locust control as the most appropriate techniques are not always readily understood."},{"index":5,"size":112,"text":"Both safety and effectiveness of pesticide use are to a large extent, determined by their method of application. In most cases of locust control, pesticides are applied using rotary atomisers to create a mist of small uniform sized droplets. The range of spraying equipment available is relatively sophisticated, thus requiring a high level of maintenance, training and skill in operation. By understanding the nature of locust and grasshopper outbreaks and the challenges involved in control, researchers can assist in improving current practices of pesticide application, increase control efficacy and improve safety for operators. Furthermore, an increase in control efficacy will result in a reduced pesticide use, lower costs and less environmental impact."},{"index":6,"size":128,"text":"Since the discovery of synthetic insecticides, application techniques for locust control have developed rapidly. Pesticides have over the years become more potent and specific and therefore demand more precision in application. Application equipment has also dramatically improved thanks to the development of new materials and technologies. This resulted in significant improvement of ultra low volume (ULV) equipment and today it is widely used in aerial and ground spraying. During the 80's, more than 90 % of locust control applications were performed by implementing this technique, while water-based spraying, baits and dusting applications were negligible. Therefore the ULV technique and its equipment is an important tool in locust control and this book attempts to provide operators with a useful and practical manual, to guide them in the application process."},{"index":7,"size":33,"text":"To be effective, any crop protection treatment should be applied at the right moment, in the right place, using the relevant product with the correct equipment, which should be well calibrated before application."},{"index":8,"size":10,"text":"These precautions are crucial to avoid misapplications which lead to:"},{"index":9,"size":20,"text":"• a dramatic increase in application costs; • a costly waste of chemicals, potentially hazardous for humans and the environment;"},{"index":10,"size":9,"text":"• increased risk to operators and non target organisms;"},{"index":11,"size":7,"text":"• excessive residues that contaminate the environment."},{"index":12,"size":30,"text":"Poor calibration of equipment has other consequences. Failures in applications are often mistakenly attributed to failure of products. Sometimes when a treatment looks ineffective, operators overdose or apply multiple treatments."},{"index":13,"size":64,"text":"This manual is intended to address application errors and the misuse of pesticides. The first section is concerned with the principles of ULV application addressing issues of droplet generation and meteorology. The second section introduces the various types of aerial and ground application equipment and the third section is concerned with operational procedures to maximise control efficacy, operator and environmental safety and minimise waste."}]},{"head":"Spraying Principles","index":4,"paragraphs":[{"index":1,"size":110,"text":"The application of crop protection products involves the atomisation of spray liquid into numerous droplets which are then dispersed over the target area. However, this definition is simplistic. To achieve accurate distribution on the target area requires the production of spray droplets of an appropriate size, neither too large which fall out onto the ground or too small which drift off target. It is therefore important to understand the mechanics of spray droplet formation in order to understand how to select the most appropriate equipment and to teach operators to correctly calibrate and use only the minimal quantity of pesticide required to achieve control. This chapter consists of five parts:"},{"index":2,"size":29,"text":"• The target and active ingredient. This section intends to define the locust or grasshopper target and its characteristics to find out the best way to reach this target."},{"index":3,"size":20,"text":"• The distribution and deposition of spray droplets. This section discusses the droplet generation and methods of spray deposit assessment."},{"index":4,"size":22,"text":"• Spray volumes. The description of spraying modes make it possible to prevent ambiguities which often induce wrong choice of anti-locust equipments."},{"index":5,"size":35,"text":"• droplet transport. The study of these concepts reveals the importance of the action of atmospheric agents upon spraying, particularly ULV technique. A good knowledge of atmospheric phenomena is essential to correctly perform ULV spraying."},{"index":6,"size":25,"text":"• assessment of the spray quality. The aim is to ensure that a spray is in accordance with the requirement and rectify any calibration error."}]},{"head":"Target and active ingredient","index":5,"paragraphs":[{"index":1,"size":104,"text":"To be efficient, a crop protection application should, at first, define the target in terms of time and space. A spray treatment will be most efficient if it is applied when the target pest is most susceptible, which requires knowledge of the target pest biology and behaviour. The space in which the target pest moves during the residual activity period of a given pesticide, should be understood. In fact, a given number of hoppers do not cover the same area as the equivalent number of flying locusts. The approach adopted with a locust should not be the same as for another locust or grasshopper."},{"index":2,"size":275,"text":"Pesticide that does not reach its target is wasted and is an economic loss and an unnecessary hazard to the environment. Therefore, a good application should aim at achieving the maximum control with minimum contamination of non target area. This means that an application technique should attempt to reduce the quantity of pesticide while raising the quantity that actually reaches the target. This implies reducing leaching and uncontrolled drift. Whatever the pesticide, its mode of action should be known because all active ingredients are not the same. Contact acting, for example pyrethroids and organophosphates should not be applied in the same manner as IGRs (Insect Growth Regulators). To be efficient the contact acting pesticides must target the insect directly while the latter affects insects only after ingestion of contaminated vegetation. These data and the environmental characteristics should be considered for defining the spraying parameters which ensure the best way to attain the acridid target. Except settled swarms or isolated hopper bands, the locust or grasshopper target generally consists of scattered population (scattered adults, scattered hopper bands) and the most frequent approach is to spray a defined area in which the insects wander, rather than treating directly the insects. In this case it is better to call it a target area. defining the target in terms of both time and space and the dose is the main factor for defining the objective of the treatment. The locust target to be determined can be under three biological stages: egg, larvae (hoppers) or imago (adult). Being buried in the soil, the eggs are sheltered from sprayed insecticides. Hence it is hoppers and adults that constitute the locust target."},{"index":3,"size":105,"text":"To define the locust target, several factors should be considered: threat The threat posed by a locust infestation must be considered in both immediate and future time frame. Thereby the threat of a grasshopper population should be assessed according to the proximity and the susceptibility of susceptible crops; e.g. a field of millet is very susceptible at the emergence and grain formation stages. In contrast, a population of locust will be considered an appropriate target, as soon as it attains the gregarious stage, even when it is hundreds of kilometres away from any crop. This may seem disproportionate with regards to the evidence of damages."}]},{"head":"Susceptibility","index":6,"paragraphs":[{"index":1,"size":127,"text":"Hoppers, mainly young instars are reputed to be more susceptible than adults. The fact that they do not move very far makes them easier to control. Hoppers and adults may be more easily controlled in an open field rather than in a shrubby area or under a canopy. mobility Locust adults may fly over tens or even hundreds of kilometres per day. During their life they may traverse thousands of kilometres. Swarms are good targets only when they settle, especially if they are less mobile when cold. Under hot conditions, the target is three-dimensional and fleeting. The same swarm can be seen in many places almost at the same time. In that case the biological target is capable of moving more rapidly than survey and control teams."},{"index":2,"size":50,"text":"Hoppers are less mobile than adults as they only move by marching or leaping. Thus they form a more practical target. Hopper bands may march up to several kilometres per day. They constitute a relatively sedentary target for a few weeks which once located are easy to follow and treat."}]},{"head":"Size","index":7,"paragraphs":[{"index":1,"size":109,"text":"Within a uniform habitat where target outlines are similar, adults and nymphs of grasshoppers generally occupy the same space, whereas the area occupied by a swarm markedly varies during the day with temperature, wind, air stability, the nature and the structure of plant canopy and also with locust activity. Besides, it is frequent that a swarm infests an area twenty times larger than that covered by the hopper band from which it was originated. An inappropriate approach to treating a large swarm may result in partial efficacy and a fragmentation into isolated swarms, thereby creating many other targets covering a larger area and therefore much more difficult to control."},{"index":2,"size":66,"text":"Hopper bands of locusts are often very dense, particularly at the young instar stages. Several thousand per square metre are often observed. The area covered by a hopper band may vary from less than a square metre to hundreds of hectares (fig. 1). They may break up into smaller bands but rarely disperse by individual means. Hopper bands are good target easy to define once located. "}]},{"head":"Spray volume","index":8,"paragraphs":[{"index":1,"size":50,"text":"The need to rapidly treat large areas particularly during Desert locust plagues, necessitates the implementation of considerable logistic resources. The need to apply products quickly had led to the development of Ultra Low Volume application technique to eliminate the need to mix products in water and treat vast areas quickly."},{"index":2,"size":402,"text":"Research with the exhaust nozzle sprayer (ENS) demonstrated that efficacy was improved by reducing the volume applied as droplet size decreased and droplet number increased. consequently, utilizing a uniform spray with a small droplet size is much more efficacious than applying a higher volume of liquid. Classifications of sprays according to the volume applied per hectare are based on subjective criteria. The following classification distinguishes five types (tab. I): high volume (HV), medium volume (MV), low volume (LV), very low volume (VLV) and ultra low volume (ULV). The ULV technique uses an application volume as small as possible while still conserving an optimal efficacy. Generally in crop protection the volume of spray applied depends on the type of target and the characteristics of the habitats such as plant coverage (tab. I). Sometimes, the type and active ingredient content of the formulation determine the volume of application in spite of target zone requirements. It is the responsibility of locust control officials, at national and regional levels, to assess the situation and provide their field staff with the most relevant formulation in order to meet the target requirement. Generally with aerial treatment, the volume of application seldom exceeds 1 litre per hectare as most operations take place in the areas with a low plant cover. However it is judicious to fix some limits so as to avoid excess. For practical purposes the lower spray volumes applied by air are 0.5 l/ha. However to apply such low volumes requires relatively uniform spray droplet sizes with µm around 50-60 µm. Use of uniform sized droplets is referred to as Controlled Droplet Application (CDA) after Mathews (1985). ULV applications with water-based formulations are not suitable because locust and grasshopper control most often take place under hot and dry conditions and droplets under 200 microns are susceptible to quick evaporation. Spraying for locust control can be defined as ULV: a technique for producing even sized and small droplets using oil formulations with application volumes less than five litres per hectare. ULV formulations almost always are oil-based and applied without mixing (ready to use). When it is required to decrease dose rate or to rise the volume of application, it is possible to mix the original formulation with an oil. This oil should, of course be compatible so, tests should be made before final mixing. In this regard, the manufacturer of the pesticide should be consulted for recommended diluent."}]},{"head":"calibration","index":9,"paragraphs":[{"index":1,"size":58,"text":"A formulation contains 450 g a.i./l. How much diesel must be added so that it is possible to treat a Desert locust infestation with 200 g a.i./ha or a grasshopper infestation with 150 g a.i./ha. In both cases the volume of application is 1 l/ha. Note: to facilitate the calculations, cm³ or millilitres (ml) are adopted as units."},{"index":2,"size":97,"text":"First, the quantity of formulation containing the dose should be determined. For this purpose use the formula: Then, the quantity of oil diluent to add will be: for Desert locust: 1,000 -444 = 556 ml for grasshoppers: 1,000 -333 = 667 ml So, 444 ml of original formulation will be mixed with 556 ml of diesel oil (444 + 556 = 1,000 ml) for treating 1 ha of Desert locust and 333 ml of original formulation will be mixed with 667 ml of diesel oil (333 + 667 = 1,000 ml) for treating 1 ha of grasshoppers."}]},{"head":"Droplet density and spray coverage","index":10,"paragraphs":[{"index":1,"size":101,"text":"The spray coverage is the number of droplets per unit area reaching the target. It can be assessed and expressed by the number of droplets per cm² and is usually measured on the vegetation or oil sensitive paper targets placed in the vegetation on which the locusts move and feed. it should be noted that the density of droplets that contact the foliage in the target zone is high when the size is small and the efficacy is better when droplet number is high. So it is more efficacious to spray with numerous small droplets rather than a few large drops."},{"index":2,"size":23,"text":"table ii. Volume of application (in l/ha) for spraying ULV and VLV, in relation to the vegetation and the type of equipment used."},{"index":3,"size":47,"text":"Usually for ULV spraying, twenty droplets per cm² are sufficient with a contact acting insecticide, while in barrier treatment with persistent insecticides, the coverage decreases with downwind swath. Formerly, barrier treatments operated with dieldrin, had a good efficacy with 1 to 5 droplets per cm² (Castel, 1982)."},{"index":4,"size":21,"text":"except in barrier treatment, in most cases of acridid control, 20 droplets per cm² are sufficient to ensure an acceptable efficacy."}]},{"head":"Droplet size","index":11,"paragraphs":[{"index":1,"size":17,"text":"When a droplet is falling, it forms a sphere. The diameter of the droplet indicates its size."},{"index":2,"size":108,"text":"In the previous paragraph, it has been stressed that with equal doses the efficacy of a treatment is better when droplets are small rather than when they are larger. This is evident because small droplets have a better penetration into the foliage and thus the coverage is better. Similarly smaller drops are more effective at intercepting flying insects. For a given volume, small droplets cover a wider area, since the number of droplets available from a given volume is inversely related to the diameter. Thus, dividing by two the diameter of a droplet results in multiplying by eight their number and by two the area covered (fig. 2)."},{"index":3,"size":22,"text":"It should be noted that, according to their size, the behaviour of droplets is influenced by the gravity and air movement. Thus:"},{"index":4,"size":99,"text":"• Droplets of more than 300 microns fall downward, almost vertically under the force of gravity. In almost all cases these droplets will end up on the soil, because even if they are intercepted by the vegetation they are not retained (fig. 3). Large droplets contain the greater proportion of the sprayed liquid (i.e. of applied a.i.).  • Droplets between 100 and 300 microns also fall by gravity but they are subject to lateral drift by wind before being intercepted by vegetation or soil. They reach the target by sedimentation and by interception. They are moderately retained by vegetation."},{"index":5,"size":56,"text":"• Droplets within 30 and 100 microns may be carried away, far from the emission point, by lateral wind movements while sedimenting simultaneously and progressively. They reach the target mainly by interception on foliage. They have a good penetration of the plant cover and they are retained on the foliage and on insect teguments (fig. 4)."}]},{"head":"Oil formulation Water","index":12,"paragraphs":[]},{"head":"16","index":13,"paragraphs":[{"index":1,"size":3,"text":"Locust Control Handbook"},{"index":2,"size":52,"text":"One litre of liquid applied evenly over a 1 hectare area achieves the following numbers of droplet/cm²: 387 droplets of 20 microns, 298 droplets of 40 microns, 88 droplets of 60 microns, 37 droplets of 80 microns, 19 droplets of 100 microns, 11 droplets of 160 microns, 2 droplets of 200 microns."},{"index":3,"size":15,"text":"In ULV locust control, the size of useful droplets is within 50 and 100 microns."},{"index":4,"size":12,"text":"To reduce evaporation of droplets, ULV formulations should be of low volatility."}]},{"head":"Droplet spectrum","index":14,"paragraphs":[]},{"head":"Spectrum","index":15,"paragraphs":[{"index":1,"size":15,"text":"Spray atomisers generally produce a range of droplet sizes, referred to as the droplet spectrum."},{"index":2,"size":38,"text":"figure 5. Evaporation rate of an ULV formulation, compared to that of water according droplet size and the distance between the emission point and the impact (after Ciba-Geigy, 1984). The assessment was realised in laboratory at 30 °C."},{"index":3,"size":23,"text":"The droplet sizes produced by an atomiser can be expressed in various ways: the volume median diameter (VMD), the number median diameter (NMD)."},{"index":4,"size":21,"text":"table v. Longevity of droplets of water according their diameter, air temperature and relative humidity (after von Eickstedt in Gröner 1985)."}]},{"head":"Volume median diameter (VMD)","index":16,"paragraphs":[{"index":1,"size":48,"text":"The volume median diameter is the median diameter where 50 % of the spray volume is less than this sizing. Half of the volume of the spray is composed of droplets smaller than the VMD and half of it of drops larger than the VMD (fig. 7,p. 20)."},{"index":2,"size":47,"text":"Calculations can be made through image analysis of spray deposits under a microscope or using laser based particle size analysis to determine the VMD. To assess sprays quality under field conditions, the VMD may be estimated by using the following equation: vmd = 0.45 x d max"},{"index":3,"size":27,"text":"Where D max is the diameter of the largest drop (the practice of determining D max will be discussed in the paragraph entitled \"the quality of sprays\")."}]},{"head":"Number median diameter (NMD)","index":17,"paragraphs":[{"index":1,"size":20,"text":"The number median diameter is the droplet size at which 50 % of the spray droplets by number are smaller."},{"index":2,"size":122,"text":"If the droplets are ranged in order of magnitude and counted from the smallest upward, when 50 % of the number is reached then the diameter of the droplet at this median number is the NMD (fig. 7). Half of the total number of drops is below this value and half have diameters above it. On its own the NMD can be misleading in that it is influenced by large number of small drops which usually comprise only small proportion of the volume of spray liquid. By dividing the VMD by the NMD we can derive a ratio that has often been used to determine the uniformity of a droplet spectrum. The lower the two values the more uniform the droplet sizes."}]},{"head":"Uniformity of a spray","index":18,"paragraphs":[{"index":1,"size":24,"text":"As a small number of large droplets contain more liquid than a large number of small droplets, the VMD is always greater than NMD."},{"index":2,"size":61,"text":"Using the VMD/NMD ratio then the higher this value the greater the range of spray droplets. For ULV application against locusts we require a very uniform spray droplet size with VMD/NMD ratios less than 2. When SPAN is used to reflect the spray droplet size range then for locust control with ULV application we require values to be less than 1."}]},{"head":"Spatial coverage","index":19,"paragraphs":[{"index":1,"size":14,"text":"For wide area treatment, a good spray coverage is an important factor of efficacy."},{"index":2,"size":111,"text":"An important measure of spray coverage is the coefficient of variation Cv of spray deposits across the treated area. For short duration contact insecticides (less than 6 hours) the Cv should be small (less than 50 %) however with the longer acting pesticides -24 to 48hrs -this is less important as the mobility to the locust or grasshopper will bring the insect into contact with the spray deposit. For residual sprays (for example insect growth regulators) with up to 3 weeks efficacy then the uniformity of spray deposit is not important as the active ingredient can be laid down in strips or barriers through which locust and hopper band move through."},{"index":3,"size":13,"text":"For blanket treatment, a good spray coverage is an important factor of efficacy."},{"index":4,"size":38,"text":"The spatial coverage may be assessed by a ratio (fig. 8), which should be smaller as the a.i. has short residual activity. In other words the coverage should be even when the a.i. has a short residual activity."}]},{"head":"Modes of spraying","index":20,"paragraphs":[{"index":1,"size":17,"text":"Sprays may be categorised according to the mechanisms of droplet generation and the type of energy (nozzles)."}]},{"head":"Hydraulic energy nozzle","index":21,"paragraphs":[{"index":1,"size":97,"text":"Liquid is forced under pressure through a small orifice so that the liquid spreads into a thin sheet and then ruptures into droplets of different sizes. Droplet size depends on the pressure, the type of nozzle and the size of the orifice. A low pressure together with large nozzle orifices produces larges drops. Whereas a high pressure with small nozzle orifice will produce smaller drops. With this type of spray however, the droplet spectrum is always very wide. The volume of the largest droplets may be as high as one million times the volume of the smallest."},{"index":2,"size":120,"text":"There is a wide variety of nozzles with different forms and diameters of orifices available. There are several types of nozzles such as cone nozzle, fan nozzle and deflector nozzle. The flow rate and droplet size can be decreased but not sufficiently to make them small enough for ULV spraying. However, with cone nozzles (fig. 9) it is possible to perform VLV aerial spraying as the high air velocity from the aircraft will reduce droplet sizes further (fig. 10).   Hydraulic energy nozzles are rarely used in locust control as they require large amounts of water (100 up to 1,000 l per ha) which is not readily available in many desert environments and severely restricts the areas that can be treated. "}]},{"head":"Gaseous energy nozzle","index":22,"paragraphs":[{"index":1,"size":147,"text":"Droplets are formed by the action of a high velocity airstream on a thin stream of liquid at low pressure. This nozzle type is referred to as \"twin fluid\" because of the use of air and liquid. Liquid is fed at low pressure (0.2 bar). In the second the air at high velocity is produced by a turbine operated by an engine or by the power taken from the vehicle and pushed through a restrictor, producing a Venturi 1 effect in which airstream impacts the liquid (fig. 11). Impacting the liquid by a jet of air at high velocity through the restrictor disintegrates the liquid into droplets. Droplet size depends on the ratio liquid flow / air flow. Increasing in the air flow results in decreasing of droplet size and vice versa (tab. VII).  Matthews, 1985). Gaseous energy nozzles require high energy, hence high large power requirement."},{"index":2,"size":90,"text":"One example of a simpler system was the development of the exhaust nozzle sprayer (ENS). The ENS is a typical gaseous energy nozzle which was very simple in design with no moving parts. The exhaust from a vehicle engine was used to generate gaseous air flow at the nozzle to shear the droplets. Droplet spectra was wide however when the ENS was used with the persistent organochlorine Dieldrin during the 1960-70s, which was not a problem. However for more modern and less persistent contact insecticides the ENS was not appropriate.  "}]},{"head":"Locust Control Handbook","index":23,"paragraphs":[]},{"head":"Centrifugal energy nozzle (rotary atomisers)","index":24,"paragraphs":[{"index":1,"size":219,"text":"In centrifugal energy nozzle, droplets are formed by a high speed rotation (typically 5,000-8,000 rpm) of a spray device. The liquid is fed at low pressure onto a rotating surface and the centrifugal force spreads it to the edge where the droplets are formed. The faster the rotation the greater the energy imparted and the smaller the droplets. This process allows droplet size to be adjusted independently of flow. Droplet size also depends on flow rate and the viscosity of the sprayed liquid. In other words, for a given flow rate an increase of the rotational speed results in a decrease of droplet size and vice versa. For a given rotational speed, an increase of the flow rate results in an increase of droplet size (tab. VIII). Viscosity can also play a role in droplet size but more importantly can affect flow rate particularly through adjustable valves or orifice restrictors. Higher liquid temperatures have an important influence on viscosity. Rotary nozzles can be operated by electric of hydraulic motors or fan impellors driven by an airflow or aircraft slipstream. Rotary nozzles generally produce a much more uniform droplet spectrum and have proved themselves ideal for ULV locust control at volume rates as low as 0.5 l/ha. Spinning discs or rotating cages (fig. 16 and 17) are the most common."}]},{"head":"Spinning disks","index":25,"paragraphs":[{"index":1,"size":105,"text":"Most spinning discs have a tooth form to assist with more even liquid break up at the disc edge. Some are composed of a stack of many disks (Micron X9-DD). Rotating disks are normally operated by an electric motor: Micro Ulva+, Micron X-15 of Micron Sprayers, Giro 1 of Tecnoma (fig. 14), C8 of Berthoud. Toothed disks produce droplets within a narrow spectrum: VMD varying from 40 to 80 microns and a VMD/NMD ratio from 1.2 to 1.7. Thus toothed disks provide a very good means of droplet size control for locust operation. This concept is referred to as controlled droplet application (CDA) (Bals, 1978)."}]},{"head":"Rotary cages or cylinders","index":26,"paragraphs":[{"index":1,"size":212,"text":"Rotary cages constructed from a mesh or perforated cylinders are often used on vehicle or aerial systems as fluid capacity of these devices is greater than discs. The cages consist of a cylindrical with a corrosion resistant and very fine metal wire gauze, rotating around a fixed hollow spindle (fig. 16). The cylinders are made from a high resistant plastic (fig. 17). The rotational speed of both cages and cylinders is high. Rotary nozzles may be operated either by the slipstream of flying aircraft by means of fan blades (Micronair AU5000 or ASC of Curtis Dyna-Fog), by electric power (Micronair AU6539 or Beecomist Airbi) or by a hydraulic system (Micronair AU7000). Liquid is fed through the hollow spindle then a spray deflector distributes the liquid over the rotating gauze or through the perforations. After an initial break up of the liquid, the atomisation is achieved when the liquid is accelerated at the rotating edge by centrifugal force. Until the 1980's, rotational cages and cylinders were mainly used for aerial applications. Now, after recent locust plagues many ground materials were successfully equipped with those spraying heads. Adjustment of rotational speed is made by setting the angle of the fan blades (fig. 15, 16 and 17) or by an electronic speed controller.  Matthews, 1985)."}]},{"head":"Hydraulic energy nozzle","index":27,"paragraphs":[{"index":1,"size":71,"text":"The energy that produces droplets also ejects droplets towards the target. Droplet path is very short because they are very soon stopped by the resistance of the air, even when they are emitted with a high speed in excess of 25 m/s. Only large drops are able to traverse several metres. So spraying directly onto surfaces requires that the emission point of droplets should be in the proximity to the target. "}]},{"head":"Air assisted sprayer","index":28,"paragraphs":[{"index":1,"size":86,"text":"Most ULV sprayers rely on spray transport by wind and gravity. Air assisted sprayers utilise an initial air flow to project spray droplets higher so the height of release is increased and therefore the trajectory of fallen droplets will be carried further by the prevailing wind. This type of equipment is also useful for treating trees or in areas where the wind velocity is variable to help propel spray away from the vehicle. Droplets under 100 µm are more suitable for transport in an air stream."}]},{"head":"Controlled drift spraying","index":29,"paragraphs":[{"index":1,"size":95,"text":"Most ULV relies on the wind for droplet dispersal and a technique referred to as air drift spraying simply involves the release of spray droplets above the vegetation canopy and allows the prevailing wind and gravity to disperse the spray. This allows a distance of up to 50 m to be treated in a steady wind speed (52 m/s) from a vehicle sprayer or 10 m from a hand-held sprayer. The use of ULV drift spraying relies on good and steady wind conditions, so the best time to spray is early morning or late afternoon. "}]},{"head":"Spray process droplet transport by possible swath width type of equipment","index":30,"paragraphs":[]},{"head":"Effects of gravity and sedimentation velocity","index":31,"paragraphs":[{"index":1,"size":112,"text":"A droplet released in a still atmosphere will fall vertically and accelerate under the force of gravity but will soon reaches a steady velocity at which the gravitational force is counterbalanced by aerodynamic drag force. The fall will then continue at a constant terminal velocity which is referred to as sedimentation velocity. Droplets below 100 microns reach sedimentation velocity after 25 mm while those of 500 microns after around 70 cm. Density of liquid and droplet size, together with the air density and fluidity also have an influence on sedimentation velocity. From a practical standpoint, it is considered that the determining factor of the sedimentation velocity is the droplet size (tab. X)."},{"index":2,"size":11,"text":"table X. Sedimentation velocity of different sized droplets (after Quantick, 1985)."},{"index":3,"size":25,"text":"The important point here is that the longer the droplets are airborne after release the greater the distance they will be carried by the wind."}]},{"head":"Wind speed and wind direction","index":32,"paragraphs":[{"index":1,"size":33,"text":"The wind has a great effect upon the behaviour of droplets. When the wind is steady and consistent in direction, the effect is useful for transport, distribution and carrying droplets into the foliage."},{"index":2,"size":69,"text":"Wind speed varies during the day so, if possible, it is always best to gauge wind strength and direction by measurement or by use of a simple flag. The ideal wind is from 1 to 3.5 m/s (3.6 to 12.6 km/h). When wind speeds are less than 1 m/s, it is not recommended to spray.  Matthews, 1985b). Simple and practical, this hand-held anemometer is suitable for usual acridid control."},{"index":3,"size":39,"text":"The ideal wind direction should be the 90 degrees from the spraying path. But actually, these conditions seldom happen. However, treatment is still correct as long as the wind remains above 25 degrees to the spraying path (fig. 22)."},{"index":4,"size":61,"text":"Observing the plant movements in the treatment site will suffice to reveal the wind direction (branches of trees and bushes or herb stems). During aerial treat-   Castel, 1982a). figure 22. Angle of spraying path to the wind direction. Drift spraying remains acceptable so long as the angle of wind direction is above 25 degrees to the spraying path (after Micron Sprayers)."}]},{"head":"25°25°S","index":33,"paragraphs":[{"index":1,"size":46,"text":"praying Principles 31 ments, a source of smoke will be suitable for it can be observed from a great distance by the pilot. For ground treatment, a bright coloured (tissue or plastic) strip fixed on top of a stake is sufficient to indicate the wind direction."}]},{"head":"Spray emission height","index":34,"paragraphs":[{"index":1,"size":47,"text":"Since droplets are likely to deposit at variable distances from their emission point, according to their size and the prevailing wind speed, it is possible to determine the actual swath width and fix the track spacing i.e. the distance between successive passes of the vehicle while spraying. "}]},{"head":"Moderate breeze","index":35,"paragraphs":[{"index":1,"size":13,"text":"Rising of some dust and papers ; small branches move. 6.7 5.5 -7.9"},{"index":2,"size":57,"text":"With no wind, droplets will fall vertically under the force of gravity. The falling time depends upon the size of each droplet (tab. X). Thus, the smaller they are, the longer they will stay airborne and drift with lateral wind. The smallest droplets will travel farther than the largest. The latter will impact near their emission point."},{"index":3,"size":32,"text":"If the emission point is increased, droplets will drift further. The distance traversed by droplets before impacting results from both effects of gravity speed. This relation is summarised by the following formula:"},{"index":4,"size":21,"text":"is the distance a droplet travels horizontally from the vertical of the emission point. It is expressed in metres (m). H:"},{"index":5,"size":12,"text":"is the height of the emission point, expressed in metres (m). U:"},{"index":6,"size":14,"text":"is the mean wind force during fall, expressed in metres per second (m/s). Vs:"},{"index":7,"size":15,"text":"is the sedimentation velocity of the droplet size range, expressed in metres per second (m/s)."},{"index":8,"size":39,"text":"accordingly, droplets always deposit at the same distance \"d\" if the product \"h x U\" is constant. So, to keep the same swath width, the emission height should be lowered if the lateral wind speeds up and vice versa."},{"index":9,"size":30,"text":"Although droplets larger and smaller, respectively than 30 and 120 microns may enhance general efficacy, it is usually admitted that useful droplets are comprised within 30 and 120 (Bals, 1978). "}]},{"head":"example of downwind distance calculation","index":36,"paragraphs":[]},{"head":"Effect of atmospheric stability","index":37,"paragraphs":[{"index":1,"size":296,"text":"It is well-known that in tropical climates temperatures normally decrease with increasing altitude. The rate decrease with height is referred to as the temperature lapse rate. Observations from sounding balloons reveal that the temperature lapse rate varies from place to place and from time to time. A typical lapse rate is around 1 o C decrease in temperature for each increase of 100 m. However under certain conditions the temperature can actually increase with height, a phenomena which referred to as an inversion. Inversion usually occurs in the low atmospheric layers, notably in the evening and early morning when the ground loses heat by radiation and is more cooler than the air above it. The surrounding air becomes cooler and tends to be heavier. Under inversion conditions temperatures increase with the height up to 10 to 15 m, then the temperature lapse rate prevails. Normally inversion is greatest in the morning at dawn just before sunrise. The atmosphere is then stable with almost total absence of turbulence i.e. there is no vertical air movements. There is an inversion when the air temperature at 2 m off the ground is 0.6° C higher than on the surface of the soil. After sunrise, the mass of air which is close to the ground is warmed by radiation from the sun and will start to rise. It will continue to do so while it remains hotter and lighter than the surrounding air. This will result in a convective movement of air in an unstable atmosphere and thus turbulence conditions are enhanced (fig. 23). Under these conditions, successful deposits of the pesticide to the target site are reduced and erratic. On the other hand, inversions do not take place in still air and will not be problematic for aerial applications."},{"index":2,"size":98,"text":"In tropical zones a day may be divided into several periods which are more or less suitable for drift spraying, owing to daily variation of atmospheric conditions. The magnitude of these suitable periods may vary with atmospheric conditions (temperature relative humidity and clouds). Practically (fig. 24), treatments utilizing CDS are possible in the morning between sunrise and around 10 a.m. and from 4 p.m. to sunset. At mid day, when there is no inversion droplet deposit is hindered by turbulence. therefore it is generally advisable to avoid drift spraying from 10 a.m. to 4 p.m.  (after Castel, 1982b)."},{"index":3,"size":32,"text":"1: period of inversion; usually suitable 2: period with rising temperature suitable for drift spraying 3: period with slight turbulences drift spraying still acceptable 4: period of strong turbulences; unsuitable for spraying"}]},{"head":"ULV formulations","index":38,"paragraphs":[{"index":1,"size":14,"text":"Physical properties of formulations plays an important role in the quality of ULV spraying."},{"index":2,"size":11,"text":"ULV formulations are oily and are generally supplied \"ready to use\"."},{"index":3,"size":21,"text":"Occasionally ULV formulation will be diluted with an oil adjuvant such as diesel oil to reduce the concentration of active ingredient."},{"index":4,"size":12,"text":"The main physical properties of formulations which influence the spraying quality are:"}]},{"head":"-Specific gravity","index":39,"paragraphs":[{"index":1,"size":12,"text":"The specific gravity of ULV formulations is generally between 0.9 to 1.2."}]},{"head":"-volatility","index":40,"paragraphs":[{"index":1,"size":103,"text":"ULV spraying requires use of very small droplets. The surface area of small droplets is relatively large with respect to the volume. This implies that the rate of evaporation is higher with smaller droplets. If highly volatile solvents are used in ULV formulations, the evaporation from the small droplets would be high. The resulting droplets can very soon be in the aerosol range and might even become small dust particles that would stay suspended in the atmosphere. Therefore ULV formulations should be of low volatility to prevent loss of material through evaporation. For the same reasons water should not be used in ULV."}]},{"head":"-viscosity","index":41,"paragraphs":[{"index":1,"size":95,"text":"Viscosity is defined as a fluids resistance to shearing. Viscosity is important for two reasons. The first is that viscous products are more difficult to pump and deliver through pipe work and orifices. Flow rates with highly viscous products can be low and inconsistent. Secondly high viscosity formulations can adversely affect droplet formation creating larger spray droplets. Therefore an ideal range for ULV formulation is generally between 5-30cP. The viscosity of a fluid is measured in units of a centipoise (cP). The thicker the liquid, the greater the viscosity and the higher the cP number."},{"index":2,"size":71,"text":"When spraying a viscous formulation, the greater part of the volume is composed of large drops. Consequently, poor coverage is obtained, versus the fluid formulations with which far better coverage can be obtained. Thus the viscosity has an influence on the spraying quality and it is an important factor to be considered for flow rate calibrations (tab. XII) and swath width, especially if it varies greatly with the variation of temperature."},{"index":3,"size":37,"text":"The viscosity of formulations varies with the nature of solvent (tab. XIII) and the effect of temperature might be more or less important. The viscosity of water is 1 cP, that of technical Malathion is 45 cP."},{"index":4,"size":56,"text":"Flow rate calibration should be done under temperature close to that under which treatments are executed. When writing purchase conditions, it is recommended to demand that physical properties should be clearly specified on the labels, because these data are needed for application officers to correctly make calibrations and for aircraft pilots to optimize loading ratio product/fuel."}]},{"head":"Assessment of spraying","index":42,"paragraphs":[]},{"head":"Necessity of assessing sprays","index":43,"paragraphs":[{"index":1,"size":26,"text":"In most cases of poor control, the cause is usually attributed to product failure but more often than not the cause is due to poor application."},{"index":2,"size":27,"text":"There are a variety of methods to check the application from checking the calibration and dosage applied is correct to checking the spray deposit in the field. "}]},{"head":"36","index":44,"paragraphs":[{"index":1,"size":29,"text":"Locust Control Handbook Droplets can be collected on oil sensitive papers or high gloss photographic paper with a dye added to the spray to aid in identifying spray drops."}]},{"head":"Collecting droplets","index":45,"paragraphs":[{"index":1,"size":90,"text":"Usually droplets patterns are fixed on artificial collectors where droplets leave permanent marks. There are different types of collection surfaces: • glossy papers or coated glass plates; • sensitive papers. Using oil sensitive papers is simple and easy. The method does not require particular skill and the results are sufficiently reliable. Two types of sensitive papers are used: oil sensitive papers for ULV oil-based formulations and water sensitive paper for water-based formulations. Both might be supplied as rolls to be cut or ready for use cards (52 x 75 mm)."}]},{"head":"Oil sensitive papers","index":46,"paragraphs":[{"index":1,"size":39,"text":"Oil sensitive papers are rigid black coloured papers coated with a thin white layer of oil soluble wax. When a droplet impacts the paper, the waxy surface is Papers should be placed so that sensitive layer faces the wind."},{"index":2,"size":53,"text":"dissolved leaving permanent black marks proportional to droplet size. The impact diameter is always larger than that of the droplet from which it originated. The stain on the paper is related to the actual droplet size by means of the spread factor, i.e. the ratio of the stain size to the droplet size."},{"index":3,"size":77,"text":"Unfortunately oil sensitive papers do not work with all ULV formulations as it requires a solvent to dissolve in and just using vegetable oil is not suitable. Actually marking property of a given formulation is not known. Thus it might be necessary to spray the paper, leave it to dry and check whether or not the black stain remains on the paper. Some carriers were tested for the marking characteristics on oil sensitive paper CF1 (tab. XIV)."},{"index":4,"size":59,"text":"Papers should be placed so that they could be impacted the same way as the target -usually positioned vertically on a rod or stick. To assess spray penetration, mark also upper, middle and lower position within the canopy. This process is also used to assess the swath width. Collecting droplets on sensitive papers requires good organization of successive operations:"},{"index":5,"size":38,"text":"• Sensitive papers should be handled with care. Do not rub them together or touch them with fingers or anything greasy, because the wax layer is very fragile and it is liable to be marked by wrong impacts."},{"index":6,"size":15,"text":"• Sensitive papers should be numbered on the back before being fixed on supports (stakes)."},{"index":7,"size":31,"text":"• Sensitive papers will preferably be fixed on a wind vane or fixed on a plate positioned at 45-90 o relative to the soil surface, a few centimetres above the foliage. "}]},{"head":"38","index":47,"paragraphs":[{"index":1,"size":3,"text":"Locust Control Handbook"},{"index":2,"size":18,"text":"• Sensitive papers will be maintained on their support by means of clothes peg, clips or rubber bands."},{"index":3,"size":18,"text":"• Stakes should be placed so that the sensitive face of the papers faces the wind (fig. 25)."},{"index":4,"size":36,"text":"• If the target zone is covered with shrub like vegetation or bushes, spray penetration can be assessed by placing some papers in the lower, the middle and the upper position within the canopy (fig. 26)."},{"index":5,"size":113,"text":"• Collectors (papers and their supports) should be lined up facing the wind at right angle to the direction of the spray path (fig. 27). The distance between collectors depends on the sprayer type. Collectors will be placed every 0.5 m or 1 m on a distance of 50 to 100 m with hand-held ULV sprayers; every 5 to 10 m, on a distance of 100 to 200 m with vehicle-mounted sprayers. For aerial spraying, interval will be 5 to 30 m a minimum distance of 200 m, the maximum distance may attain 2,000 m (barrier treatment). The distance along which collectors are placed should equal, at least, twice the expected swath width."},{"index":6,"size":16,"text":"• When possible two or three lines of collectors, separated by 100 m, should be placed."},{"index":7,"size":14,"text":"• Spray should start at least 100 m before the first line of collectors."},{"index":8,"size":26,"text":"• Under aerial treatment, wait a few minutes after the spray flight before picking up the papers, thus fine droplets will have enough time to deposit."},{"index":9,"size":12,"text":"• For calibrations, a quick glance will give indications for targeting modifications."},{"index":10,"size":22,"text":"It may be possible to compare papers just after their impingement with standard cards with known VMD and droplet density (fig. 28)."},{"index":11,"size":31,"text":"• For thorough assessment, papers should be collected with great care and put away, each serial in a separate and labelled envelope. They will be stored with care for further investigations."}]},{"head":"Water sensitive papers","index":48,"paragraphs":[{"index":1,"size":43,"text":"Water sensitive papers have a coated yellow surface which will be stained dark blue by aqueous droplets impinging on it. Like oil sensitive papers they are fixed on rigid support or clipped directly to foliage of plants at different levels within the canopy."},{"index":2,"size":36,"text":"On the site, after treatment, impinged papers might be compared with standard cards bearing known VMD and droplet densities (fig. 29) to estimate deposit and spectrum. Some general guidelines on use of water sensitive papers are:"},{"index":3,"size":28,"text":"• When relative humidity is very high, only visual assessments can be done. Above 80 % relative humidity, papers will be over stained and thus will be unusable."},{"index":4,"size":25,"text":"• When relative humidity is under 50 %, droplets smaller than 50 microns do not impinge on the paper because they evaporate before impacting it."},{"index":5,"size":16,"text":"• Papers should not be used early morning if the crop is still wet with dew."},{"index":6,"size":11,"text":"• When fixing the papers make sure the supports are dry."},{"index":7,"size":14,"text":"• Before pinning up papers on their supports, it is recommended to number them."},{"index":8,"size":22,"text":"• Papers should be handled with care and particularly not contacted with fingers or anything humid. When possible use clean, dry gloves."},{"index":9,"size":23,"text":"• Supports should be driven into the soil every 2 or 3 m slightly above the soil surface or just above the foliage."},{"index":10,"size":24,"text":"• If the object is to check the swath width and perform calibrations of the speed, the output should be done before droplet collecting."},{"index":11,"size":17,"text":"• After impaction, papers should be collected only when dry and stored in an air tight container."}]},{"head":"Analysis of oil and water sensitive papers","index":49,"paragraphs":[{"index":1,"size":26,"text":"Analysis of oil or water sensitive papers can be made manually with a microscope and calibrated optics to size the droplets or using image analysis software."},{"index":2,"size":25,"text":"As droplets spread upon impact it is important to know the spread factor of the formulation used and also this will vary with droplet size."},{"index":3,"size":49,"text":"For accurate spray assessments, like those required for insecticide experiments and evaluation of spraying equipment, it is necessary to determine the exact table Xv. Spread factor that can be used in the fi eld, according to the formulation type and the droplet size (after Ciba, 1983 andCastel, 1986) ."},{"index":4,"size":19,"text":"Spraying Principles 41 spread factor of the formulation utilized. Collaboration with manufacturers is recommended to obtain this important data."},{"index":5,"size":17,"text":"In most cases, using standardized spread factors enables to obtain quick and sufficiently liable results (tab. XV)."}]},{"head":"Image analysis","index":50,"paragraphs":[{"index":1,"size":91,"text":"Generally, image analysis is made using a microscope equipped with a digital camera or scanner to capture images, and these are then processed by computer using image analysis software. This will calculate the range of droplet sizes by counting pixels on the digital image. Size can be expressed as VMD and the range expressed as VMD/NMO ratio or spa with a histogram printout. The number of droplets is often expressed as number per cm 2 and by inputting the concentration of active ingredient, the volume and dose per unit are derived."}]},{"head":"Manual analysis","index":51,"paragraphs":[{"index":1,"size":48,"text":"In most cases precise data are not required and then manual analysis could be performed, by means of foldable lens, portable microscope or binocular (magnification x 10 or 15) by using a droplet counting aid with standard windows of 1, ½ and ¼ cm² (fig. 30 and 31). "}]},{"head":"Locust Control Handbook","index":52,"paragraphs":[]},{"head":"Droplet density assessment","index":53,"paragraphs":[{"index":1,"size":61,"text":"On each paper, four counts are made in different areas at random. When droplet density is high, use the smallest window (¼ cm²). The average number of droplets per cm² in each paper is calculated and recorded for further calculations. When all papers of all series are checked, then the average droplet density is calculated for all the papers (fig. 32)."}]},{"head":"Droplet spectrum assessment","index":54,"paragraphs":[{"index":1,"size":164,"text":"The VMD calculation requires sampling of at least 200 droplets and classifying them into regularly spaced size classes as a frequency distribution. Very large drops which are obviously out of the spectrum are discarded (leaking). Then the volumes are added together starting from the smallest volume and when 50 % of the total volume is reached the diameter of the drops at this median volume is the VMD. It is possible to draw a curve of cumulated volumes and the VMD can be read at the interception of the curve and the vertical line starting from 50 % on the axis (fig. 33). Half of the volume of the spray is composed of droplets smaller than VMD and half of it is larger than the VMD. This method is tedious to carry out and it is practically impossible to use on the field so, for common assessments, \"d max \" method is accurate enough. The process for using D max method is as follows:"},{"index":2,"size":27,"text":"• Measure on each paper the two largest drops excluding those that are obviously out of spectrum i.e. those of which the immediate below class is empty."},{"index":3,"size":23,"text":"• Then calculate the diameter of the five largest droplets belonging to the highest class. This value will be considered as D max."},{"index":4,"size":59,"text":"• The VMD equals D max multiplied by the spread factor 0.45 is considered as an acceptable spread factor for usual ULV formulations. The NMD is not assessed when D max method is used. This data is required only when it is essential to know the evenness of graticule i.e. for the evaluation of equipment or expedients of insecticides."}]},{"head":"Spray distribution assessment","index":55,"paragraphs":[{"index":1,"size":181,"text":"The objective of a spray is to ensure that droplets reach the vegetation in the target zone or the biological target itself. But it should be noted that it is very difficult to obtain an even distribution of droplets on the target zone and a fortiori on the biological target. Therefore a spray has to be considered thoroughly in order to decide what distribution in the field is required to achieve a sufficient biological and economical result with the concern of preserving the environment. Thus, in acridid control, the high mobility of the insects compensates to some extent, for unevenness in the spray distribution. A visual assessment is possible by comparing visible deposit with standard cards which are subsequently calibrated by normal chemical methods. The curve of a droplet distribution is helpful. The comparison of the resulting curve with standard curves may give an idea of the coefficient of the variation of droplet distribution. When accurate figures are required, it is more advisable to use statistical analysis. The following formula may be suitable: Xi: droplet density (cm) n: number of measures"},{"index":2,"size":77,"text":"The standard deviation and the arithmetic mean might be rapidly calculated when a programmable electronic calculator is available. Practically an absolute even distribution virtually never occurs (variation ratio = 0). Actually in acridid control, important variation in spray distribution does not significantly influence the efficacy of acridicides. Moreover, barrier treatment with long residual activity insecticides may involve track spacing as wide as 2,000 m. In this case the evenness of the spray distribution becomes an unimportant factor."}]},{"head":"Checking the swath width","index":56,"paragraphs":[{"index":1,"size":76,"text":"In acridid control a visual assessment with oil sensitive papers is often sufficient to show if the swath width is wide enough (see above). If the swath width is shorter than expected, possible explanations include: • In the case of large size droplets: the size should be reduced by adjusting the setting of the atomiser. • In the case of good droplet size: the wind speed is too slow or the emission height is too low."},{"index":2,"size":25,"text":"In contrast, if the collectors are impinged only by the side downwind, it means that the There is an overdrift which might be due to:"},{"index":3,"size":32,"text":"• Too low height of release or a strong wind. In this case the emission height should be lowered or, if not possible because it is already low, treatment should be postponed."},{"index":4,"size":18,"text":"• Droplets of small size together with a narrow spectrum. In this case atomisers should be adjusted properly."}]},{"head":"Spraying Equipment foreWord","index":57,"paragraphs":[{"index":1,"size":194,"text":"The types of sprayers which are designed for locust control are relatively few. Besides, each type of sprayer has specific and precise features which confer to its own originality. For this reason, an acridid control manual, designed to be useful to operators cannot preclude presentation of available equipment and must emphasize elements which might detract from their correct uses. The advice is based on the experience of operators and is restricted to acridid control. Equipment that seem of little use in acridid control might be excellent in another field of crop protection. It is therefore clear that comparisons made here are only aimed at helping operators to optimise the use of available equipment. The opinions expressed are solely those of the author at the time of publication and recommendations are likely to change as advances in spray technology occur. All companies quoted made useful contribution. It is possible that others, which are not presently known in acridid control, might deserve to be mentioned in the future. Registered trade marks are indicated in the text by capitals so that they may easily be recognised without being emphasized by, which should be considered as systematically implicit."}]},{"head":"Portable equipment","index":58,"paragraphs":[]},{"head":"Motorized knapsack mist blower","index":59,"paragraphs":[{"index":1,"size":101,"text":"In these devices (fig. 34) the air is a determinant factor for carrying droplets to the target. Droplets are generated by a blast of air which shatters a trickle of liquid into droplets. Some mist blowers are now equipped with a rotating device. With sprayers of this type, it is possible to apply low volume (LV) of water-based emulsions. Those equipped with a good hydraulic circuit and a sound flow control valve can apply very low volume (VLV) of either water-based or oil-based formulations. For ULV spraying they should be equipped with a centrifugal apparatus which has a high rotational speed."},{"index":2,"size":49,"text":"Considering their weight and bulk, the choice of knapsack mist blowers is relevant only when it is necessary to use the air blast for treating roosting locust on trees with a maximum of 10 m height. Mist blowers are also useful for treating thick bushes where locusts may hide. "}]},{"head":"Description","index":60,"paragraphs":[{"index":1,"size":23,"text":"The main constitutive elements of the knapsack mist blower are the structure, the engine and the circuits of the air and the liquid."}]},{"head":"Structure","index":61,"paragraphs":[{"index":1,"size":92,"text":"The chassis which is \"L\" shaped should be light and strong enough to support either the engine and the sprayer. It is designed so that the sprayer remains in vertical position when it is on a horizontal surface. To soften the vibration of the running engine, the chassis has rubber shock absorbers. The straps and cushions are designed to ensure that the operator feels at ease when he carries the sprayer, which is relatively heavy. In fact, when it is empty it may weigh 14 kg and reach 24 kg when full."}]},{"head":"Engine","index":62,"paragraphs":[{"index":1,"size":238,"text":"The development of knapsack mist blowers is primarily linked to the evolution of the 2-stroke engine and the decrease of the material weight. Small capacity engines are light but powerless. Their stream is short and thus is not suitable for treating trees. Powerful engines have the capacity to run strong turbines which are capable of producing suitable streams for treating high trees and low crops when it is necessary to use an air stream to carry droplets. The rotational speed of the engine varies with models from 6,000 to 8,000 rpm. The rotational speed determines the velocity and the air flow. It is thus important to check it with a tachometer. If the rotational speed is unsuitable, the engine should be calibrated or have it fixed at the workshop. The fuel for 2-stroke engines is a mixture of oil (30 SAE viscosity) and two star petrol in 1 for 24 proportion. Multigrade oil should be excluded for this use. These machines are usually equipped with a starting device, however it does not hold up well under heavy use. Therefore it is essential that a pulley should be present so that starting the engine, by means of a rope is possible when the return device is out of order. For maintenance of the engine and moving parts, manufacturer's recommendations should be scrupulously applied. It is particularly important to ensure that, in all circumstances, cooling fins should be kept clean."}]},{"head":"Air stream circuit","index":63,"paragraphs":[{"index":1,"size":96,"text":"The air stream produced by the turbine is forced into a hose terminating in a restrictor (also called a Venturi) where the air stream and the product meet (fig. 35). When CDS is used, the hose is fixed in an upward position so that the operator's hand are free. Thus his attention is free to monitor his walking speed (fig. 36). figure 36. Note the position of the hose in such a manner as to allow the operator's hand to be free and encourages individuals to focus on keeping a steady pace walking (after Matthews, 1985b)."},{"index":2,"size":30,"text":"Inside the Venturi is located in the droplet maker's device. Since the re-emergence of locust outbreaks, some manufacturers have designed, with more or less success, centrifugal apparatus within the Venturi."}]},{"head":"The liquid circuit tank","index":64,"paragraphs":[{"index":1,"size":197,"text":"The insecticide tank, usually 10 l capacity, is made of plastic and has variable shapes. The filler hole is wide and equipped with a fitter, which should always be in place for filling. The cap includes a seal to ensure that the light pressure (0.2 bars) is sufficient for bringing the liquid from the tank to the restrictor. If the sprayer is equipped with VLV or ULV devices, a filter should be placed at the tank and the control valve. pump Sprayers with centrifugal devices are also equipped with a small pump enabling a regular flow of the liquid, even if the gas restrictor is higher than the liquid in the tank. flow regulator To ensure a good flow control, the flow control device should be placed between the tank and the gas restrictor. The device could be either a flow regulator or interchangeable orifice restrictors. Starting and stopping the spray is done by means of an on/off valve. VLV and ULV mist-blowers should always be equipped with a flow control valve accurate and easy to adjust. Particularly, it should be detached from the on/off valve. The progressive valves are not accurate enough to monitor small flows."}]},{"head":"Spraying devices","index":65,"paragraphs":[{"index":1,"size":147,"text":"Many brands and types of knapsack mist blowers are available in the market. During the last ten years, bilateral aids have made donations of many different brands and types of mist blowers. This disparity also results in a diversity of spray heads from a plain hose which emerge onto the gas restrictor to centrifugal apparatus which rotate more or less rapidly. Almost all manufacturers supply special nozzles to decrease the liquid flow, asserting that these devices are suitable for ULV spaying. However, since the principle of droplet generation is unchanged (gaseous energy), the droplet spectrum is too coarse to allow an acceptable ULV spraying. Some manufacturers got the idea, that is why they adopted centrifugal devices, with varying degrees of success. The main error committed is to enlarge the pipe head to install the rotating device which results in a dramatic slowing down of the air stream."},{"index":2,"size":107,"text":"adaptation of a rotating cage: micronair aU8000 AU8000 atomiser of Micronair is designed to equip knapsack mist blowers, without important modification. This spray head of 1.5 kg, is composed of a rotary cage and a restrictor unit as a flow control. It is mounted in place of the gas restrictor (fig. 37). The rotary atomiser is driven by adjustable fan blades in the air stream from the blower. The atomiser is fitted with a cylindrical metal gauze which produces droplets. If the air stream is strong enough to run the cage at 6,000 to 8,000 rpm, the droplet spectrum will be suitable for ULV spraying (fig. 38)."},{"index":3,"size":17,"text":"figure 38. Variation of droplet size with the rotational speed of AU8000 Micronair cage (after Micronair, 1989)."},{"index":4,"size":71,"text":"The flow is controlled by the interchangeable restrictor tube attached to the on/ off valve and by the chemical pressure. To facilitate flow preselection, the restrictor tubes are colour coded according to flow rates (tab. XVI). The indicated flows are given for water viscosity and thus are to be taken only as reference points for starting more appropriate calibrations. The procedure for flow calibration will be described in the next chapter."},{"index":5,"size":14,"text":"table Xvi. Flow rate of AU8000 restrictor tube, measured with kerosene (after Micronair, 1989)."},{"index":6,"size":38,"text":"As well as being purchased with the complete sprayer, assembly, the AU8000 can also be supplied as a conversion kit for mist blowers, provided that they are type of micronair aU8000 atomiser flow (litre per min) number colour"},{"index":7,"size":166,"text":"Brown Red Orange Yellow Green 0.075 0.150 0.300 0.600 1.200 powerful enough, i.e. 5 HP machine, having minimal blower output of 20 m³/min and air velocity of 125 m/sec at the outlet. The size of the droplets produced by the spray head, depends upon the rotational speed of the atomiser and the viscosity of the chemical. The rotational speed of the atomiser depends upon the air stream produced by the blower and by the angle of the fan blades. As most mist blowers are designed to run at a fixed blower speed, the speed of the atomiser must be set by adjusting the angle of the fan blades. To obtain a droplet spectrum which is suitable for ULV spaying, the rotational speed of the spray head should range between 7,000 and 8,000 rpm (fig. 39). The rotational speed can be checked by means of a tachometer. If there is no tachometer, a visual assessment of droplet size will indicate if the rotational speed needs an adjustment. "}]},{"head":"adaptation of a rotating cone: micronex","index":66,"paragraphs":[{"index":1,"size":38,"text":"This device can be adapted, with or without a bottle, to the airflow nozzle. The fan is activated by the air stream up to 12,000 to 16,000 rpm. The rotational speed depends upon the power of the engine."},{"index":2,"size":85,"text":"The output might be adjusted from 30 to 100 ml/min by means of a set of colour nozzles. Droplet size can be adjusted by varying airflow or output. Droplet size might be decreased down to 40 microns. This device produces droplets with fine and homogenous spectrum. However, when the mist-blower is not powerful enough, the flow rate is not very accurate, which necessitates maintaining the nozzle below the liquid level in the formulation tank. This constraint reduces the possibility of having the widest track spacing."}]},{"head":"General functioning","index":67,"paragraphs":[{"index":1,"size":54,"text":"The proportion of oil/gasoline mixture should be kept scrupulously. The filling up should be made through a fine mesh filter by means of a funnel to avoid spilling gasoline over the engine, because it may spontaneously catch fire when it is very hot. After the filling up the filter cap should be replaced carefully."},{"index":2,"size":25,"text":"To start the engine, follow carefully the procedure indicated by the manufacturer. While spraying, the engine should run at full speed for only short periods."},{"index":3,"size":51,"text":"When the sprayer is equipped with only a gaseous energy nozzle, it should be noted that with a constant liquid flow, a diminution of the air flow will result in a rising of droplet size. For a given air flow, an increase of the liquid flow will have the same effect."}]},{"head":"Hand-held ULV sprayers","index":68,"paragraphs":[{"index":1,"size":264,"text":"At he beginning of the 1960's, the necessity for reducing the volumes of application, led to the development of hand-held ULV sprayers, which are operated by torchlight batteries, R20 type. In 1975, several hundred thousands hectares of cotton were already treated by this sprayer in Western Africa (Cauquil, 1987). As they are simple and strong and because they need no water or just a small amount, they rapidly replaced the knapsack hydraulic sprayers among cotton growers. Their success was amplified by the need for frequent applications and the availability of less toxic insecticides such as pyrethroids. From 1985, hand-held ULV sprayers started to be used in acridid control, particularly against grasshoppers. Now, beside cotton, they are commonly used in tropical zones on food crops such as tomatoes, rice, maize, groundnut, millet etc. Hand-held sprayers may play an important role in acridid control, particularly for close protection of food crops and whenever farmer participation is necessary for technical or social reasons. At the onset of the rainy season in Sahelian countries, controlling the first hatching of grasshoppers may be critical in preserving the seedling. Although grasshopper pullulations may develop into plague, it is not conceivable to expect that National Plant Protection Services will respond everywhere to everybody at the same time. Where, formerly, dusting bags were used, hand-held sprayers will advantageously be a substitute. Besides, chemical companies have now introduced many special formulations for use with this type of sprayer, which can be used either with water or oil based sprays. However it should be recommended that those formulations, be of low toxicity to human."}]},{"head":"Description","index":69,"paragraphs":[{"index":1,"size":40,"text":"The constitutive elements of hand-held sprayers are the tubular handle, the head locking sleeve, the electric motor, the energy source, the bottle, the tank and the atomiser disc (fig. 40). They are relatively light weighing around 1.7 to 1.9 kg. "}]},{"head":"Tubular handle","index":70,"paragraphs":[{"index":1,"size":65,"text":"The handle has several roles: casing the batteries, varying the droplet emission height, handling the sprayer. At the bottom, there is the on/off switch. Most of hand-held sprayers are now equipped with a telescopic lance made of aluminium. The battery case is made of plastic (Berthoud) or aluminium (Micron Sprayers). C5 of Berthoud contains 5 batteries and Micro Ulva+ of Micron Sprayers, 5 to 8."}]},{"head":"Head locking sleeve","index":71,"paragraphs":[{"index":1,"size":37,"text":"The head locking sleeve is made of plastic or metal. It enables the setting of the head angle to the extension tube so that the nozzle axis is maintained at vertical position, according to the emission height."}]},{"head":"Electric motor and energy source","index":72,"paragraphs":[{"index":1,"size":90,"text":"The motor is placed in a sealed plastic housing. It is powered by torch (D-cell/ R21) batteries under a voltage which varies from 6 to 12 volts, with the number of batteries. The disc is thus denticulate at 4,000 to 10,000 rpm and the highest speed is used for ULV treatment while the slowest is for water-based applications including herbicides. Most of models have a fixed rotational speed while Micro Ulva+ models may run at different rotational speed according to the number of batteries inserted in the case (tab. XVII)."},{"index":2,"size":21,"text":"table Xvii. Droplet size against fl ow rate and rotational speed of the disc for the Micro Ulva+ (after Micron Sprayers)."},{"index":3,"size":98,"text":"Consumption of energy and the wearing out of batteries depend upon the consumed power and the efficiency of the motor. Some motors consume more energy than others. The way of working also has its importance in the batteries wearing out. Thus, after a working period, the voltage decreases. Normally, after a rest period, a repolarisation occurs with a voltage recovery. Hence, it is recommended to alternate five minutes rest with twenty minutes of continuous spraying. Whenever possible, it is better to use alkaline batteries than saline, because the latter are less efficient and less resistant to intensive use."}]},{"head":"Bottle and additional tank","index":73,"paragraphs":[{"index":1,"size":125,"text":"The bottle, 1 litre capacity, is made of translucent plastic. This low capacity is not tyring for operators. The sprayer, with 1 litre of product in the bottle and loaded with 8 batteries, weighs approximately 2.5 kg. The bottles are calibrated, some with 0.250 l graduations others 0.200 l graduations, which enables the operator to check the variation of the product level in the bottle. If required it is possible to add more graduations by waterproof ink. Some models of sprayers have a filling hole independent from the neck (fig. 41) in addition to a refilling point that can be connected to an additional tank. All are designed to ensure an introduction of air in the bottle, thus enabling a regular flow of the product."},{"index":2,"size":32,"text":"figure 41. Diagram of the head of a hand-held ULV sprayer (after Micron Sprayers). The spray head can be adjusted so that the feed nozzle is as close to vertical as possible."},{"index":3,"size":63,"text":"Most of manufacturers now supply a backpack tank to be used for refilling directly the bottle fitted with the spray head. This tank is connected to the bottle by means of a hose and an on/off valve. Transferring the product from the tank to the bottle is carried out by placing the base of the bottle on the ground and opening the valve."}]},{"head":"Nozzles","index":74,"paragraphs":[{"index":1,"size":18,"text":"Manufacturers provide with each model a set of coloured nozzles with different diameters corresponding to different flow rates."},{"index":2,"size":57,"text":"It should be noted that the same colour does not correspond to the same diameter of sprayers from different manufacturers. So, it is recommended to refer to the instruction manual for identification of nozzle diameters. It is advisable that manufacturers use the same colour for the same diameter. Usually, nozzles can be changed without using any tools."},{"index":3,"size":44,"text":"Tables of flow rate given by the manufacturer are measured with water and sometimes with surfactant. They are only to be taken as an indication for more accurate calibrations. ULV formulations have different viscosities and should always be measured before spraying a new product."}]},{"head":"Atomiser discs","index":75,"paragraphs":[{"index":1,"size":58,"text":"There are different shapes of discs: dish form with a curved rim and more or less open cup, 50 to 80 cm diameter. They are fixed on the motor axis by a clip or a screw. They all can be replaced if they are damaged. All sprayers are provided with a protective cover to prevent discs from impacts."},{"index":2,"size":19,"text":"Disc rim may be denticulate or smooth. Denticulate discs produce the narrowest droplet spectrum, however they are more fragile."}]},{"head":"Functioning of hand-held sprayers","index":76,"paragraphs":[{"index":1,"size":42,"text":"Liquid is fed by gravity through a nozzle to the disc centre and the centrifugal force spreads the liquid as explained in the preceding chapter. For a given viscosity, droplet size varies with the rotational speed and the flow rate (tab. VII)."}]},{"head":"Vehicle-mounted sprayers","index":77,"paragraphs":[{"index":1,"size":57,"text":"Until the late 1980's, only the exhaust nozzle sprayer (ENS) was available as the vehicle-mounted sprayer. Introduction in the market of electrical vehicle-mounted sprayers was considered as notable progress since the electrical energy does not affect the motor of the vehicle. Since then, they were being improved under the constraints of rough working conditions in desertic zones."},{"index":2,"size":156,"text":"Vehicle-mounted sprayers are dependent, more or less closely to the vehicle. The most dependent is the exhaust nozzle sprayer since it is entirely submitted to the power of the vehicle (volume and the stream of exhaust gas) for producing droplets. The mechanic specifications of the vehicle are also very important for forward speed. Some are autonomous. They are only dependent upon the vehicle speed, since they have petrol or gas oil engines as their own source of energy (Micronair AU8115 of Micron Sprayers, Puma and Super Puma of Berthoud). Electric-mounted sprayers are free from the vehicle power for producing droplets but they depend upon its source of electricity and the accuracy of the dose is related to the variation of forward speed (Ulvamast of Micron Sprayers). The L15 of Curtis Dyna-Fog is dependent of the vehicle source of electricity but, thanks to its radar Syncroflow, the accuracy of the dose is free from the vehicle speed."},{"index":3,"size":20,"text":"In 1988, FAO published guidelines on minimum requirements for agricultural pesticide application equipment. Regarding vehicle-mounted sprayers, hereinafter the main requirements:"},{"index":4,"size":12,"text":"• The sprayer unit should be securely attached to the vehicle platform."},{"index":5,"size":17,"text":"• All handles, grips or hand holds should be at least 300 mm from a hinged joint."},{"index":6,"size":74,"text":"• Ideally a vehicle-mounted sprayer should be fitted with a closed transfer filling system for chemical. However, where filling is manual, it should be possible to add the chemical to the tank with the operator standing on the platform. • Reach distance for filling should not exceed 1 m vertically from the platform and 0.3 m horizontally from the body of the person pouring the chemical. This pouring zone should be free from obstruction."},{"index":7,"size":21,"text":"• The sprayer tank(s) filling system must permit safe, easy filling without overflowing or splashing at a specified maximum filling rate."},{"index":8,"size":63,"text":"• All external parts of the sprayer should be designed so that liquid is not retained on the surface of the machine and any chemical residues which accumulate can readily be washed off by a practical cleaning routine which should be defined in the sprayer manual. • There should be no sharp edge, abrasive areas or sharp projections which could cause physical injury."},{"index":9,"size":34,"text":"• The sprayer should be stable when free standing and should remain upright when positioned on a 1 in 10 slope in any direction and irrespective of the amount of liquid in the tank(s)."},{"index":10,"size":21,"text":"• Adjustment to the sprayer, routine maintenance, drainage and cleaning should be easy carried out without the use of specialised tools."},{"index":11,"size":25,"text":"• The manufacturer should provide a clear, illustrated, instruction manual in accepted commercial language for a specific market or in English, French or Arabic, etc."},{"index":12,"size":49,"text":"• The manual should contain procedure for: -initially assembly, -identification of all spare parts, -setting and calibration, -cleaning and decontamination, -routine maintenance and storage, -safe and efficient use of the sprayer, -minimising risks to the operator and the environment associated with all aspects of machine use including spray drift."},{"index":13,"size":65,"text":"• The manufacturer should also provide information on: -nozzle selection, -the maximum nozzle size and operating pressure to be used, -the handling of undiluted, -pesticide formulation during mixing (if required) and filling, -procedures for minimising the need for disposal of unused spray liquid, rinsing and washing water, -procedures for the safe disposal of any dilute pesticide, -any protective clothing requirement consistent with pesticide label recommendations."},{"index":14,"size":27,"text":"• The sprayer should be clearly and durably marked to indicate the manufacturer's name and address, sprayers name and model and should indicate the year of manufacture."},{"index":15,"size":47,"text":"• The manufacturer should provide evidence to the purchasing agency that a practical system is in place to record the machine specifications, make, model and year of manufacture so that spare parts can be accurately specified for a minimum of five years after the date of manufacture."},{"index":16,"size":15,"text":"• All controls should be easily reached by the operator in the normal working position."},{"index":17,"size":56,"text":"• All parts of the sprayer should be made from material which are non absorbent and unaffected by approved pesticide formulation and those parts which are exposed to sunlight should be made from materials do not degrade in UV light. The relevant information on material should be made available to the purchasing agency by the manufacturer."}]},{"head":"Vehicle-mounted autonomous sprayers","index":78,"paragraphs":[{"index":1,"size":144,"text":"Except for forward speed these sprayers are independent from the vehicle. The required energy is provided by an auxiliary thermal engine. In most cases they are air carrier sprayers where droplets are produced by any process (gaseous, liquid pressure or centrifugal force or a combination of two). Some of this sort of sprayers are enormous and are equipped with 50 HP thermal engines carried by tractor (fig. 42) or by lorry (fig. 43). Even if these big sprayers produce an acceptable droplet spectrum, their weight and the constraint imposed by their maintenance make them unsuitable to current uses in acridid control. figure 42. Air carrier sprayer carried by tractor (after Tecnoma, 1988). This type of sprayer can be useful to control locust adults when they are roosting on high trees. figure 43. Air carrier sprayer on a small 4-wheel drive lorry (after Berthoud, 1988)."},{"index":2,"size":54,"text":"This type of sprayer is powerful but very diffi cult to handle and to maintain in usual acridid control conditions. In contrast, small and compact sprayers that can put on the platform of any four wheel drive pick-up, may be suitable provided they generate a droplet spectrum fine enough to comply with ULV specifications."}]},{"head":"Puma air carrier sprayer of Berthoud","index":79,"paragraphs":[{"index":1,"size":230,"text":"The Puma air carrier sprayer is a compact set assembled on a steel chassis. It is fitted with an 85 l polyethylene tank, a centrifugal pump with a filter; an air steam pipe which can be set in various positions from horizontal to vertical, owing to a 45 degrees articulation (fig. 44). The energy is provided by a diesel or a gasoline engine). The diesel engine, 8 HP, is equipped with an electric starter while the gasoline motor may have electric or mechanic starter (pulley and rope). It is possible to control the spraying from inside the cab. The sprayer set weighs 94 kg with gasoline engine and 128 kg with diesel engine. It is equipped with straps with which it can be held on to the platform and transferred to another vehicle or unloaded. If necessary, it is possible to fix it to the platform with bolts and nuts. The Puma set is a pure gaseous nozzle and is fitted with a fan turbine which generates an air stream of 1,350 m³ with a speed of 408 km/h. Normally with these specifications it is possible to generate droplets having a spectrum good enough to accomplish correct very low volume applications. The flow rate is calibrated by a combination of perforated plates, coloured nozzles and a variable flow restrictor (tab. XIX). That allows a very wide range of flow rates."},{"index":2,"size":28,"text":"table XiX. Example of fl ow rate variation of water with a Puma sprayer set, equipped with a 4 mm plate and different coloured nozzles (after Berthoud, 1999)."},{"index":3,"size":22,"text":"This type of sprayer may be useful in Saharan-Sahelian zones where it is sometimes required to alternate air carrier and drift treatments."},{"index":4,"size":62,"text":"The Puma sprayer set is compact and relatively strong. It may be carried by a small pick-up, provided it is four wheel drive. It is a completely autonomous and thus it may be quickly transferred from one vehicle to another with minimal tools. However it suffers from constraints linked to the maintenance of thermal motors and its droplet spectrum is relatively coarse."}]},{"head":"Micronair AU8115","index":80,"paragraphs":[{"index":1,"size":64,"text":"This sprayer is designed to use the Micronair AU8115 spray head which uses rotary atomisation. It is self-contained and is designed for a wide range of applications including acridid control. The entire sprayer is mounted in a frame and is ready for installation in the rear of any four wheel drive vehicle. It may be necessary to make some adaptations to suit certain vehicles."},{"index":2,"size":58,"text":"The sprayer may either be permanently bolted to the platform of a vehicle or may be temporarily secured if it is not to remain on the same vehicle all the time. For permanent installation, the frame can be bolted directly to the vehicle platform or bolted to wooden cross-beams which are in turn bolted to the vehicle platform."},{"index":3,"size":23,"text":"For temporary installation, the sprayer is secured to the vehicle by means of suitable straps passed through the top corners of the frame. "}]},{"head":"Components engine","index":81,"paragraphs":[{"index":1,"size":44,"text":"It is an 11 HP air cooled 4 stroke petrol engine, powerful enough to allow derating for high temperature and altitude conditions. The engine is fitted with a rope pull recoil start mechanism. The engine is selected for the worldwide availability of spare parts."},{"index":2,"size":30,"text":"A handbook is available from the manufacturer, which explains running procedures and safety instructions. They are important and should be scrupulously followed so as to avoid any malfunction or accident."}]},{"head":"airstream system","index":82,"paragraphs":[{"index":1,"size":29,"text":"The blower unit is directly coupled to the engine crankshaft. It generates a high velocity air stream which is led to the spray head through a flexible air duct."}]},{"head":"Spray head","index":83,"paragraphs":[{"index":1,"size":181,"text":"Air driven AU8115 atomiser is mounted in an adjustable swivel which allows the variation of air stream direction. An optional extension kit is available to allow the spray head to be raised up. Thus the release height may attain 15 metres. This possibility is particularly useful when wide swaths (100 m or more) are required or for treating tall crops such as sugar cane or corn. AU8115 atomiser is built from chemical resistant materials. To ensure a long period of trouble-free performance it should not be mistreated and cleaned after use. The spray head is dynamically balanced to ensure it will rotate smoothly without vibration. Some chemicals, particularly certain solids in suspension or ULV formulations, can dry or crystallise on the gauze, blocking the mesh and causing the atomiser to vibrate. this can easily be avoided by spraying 1-2 litres of liquid from the atomiser at the end of each spray job. The liquid must be a solvent for the chemical which has been used. Water will normally only dissolve water-based formulations. Kerosene or diesel fuel is suitable for ULV products."},{"index":2,"size":19,"text":"The bearings of the AU8115 are sealed and lubricated for life. They should be replaced if they become worn."}]},{"head":"chemical feed system","index":84,"paragraphs":[{"index":1,"size":32,"text":"It is composed of a tank, chemical valves flow control valve and the filter. tank 100 l capacity tank UV stabilised high density polyethylene. 5 l graduations. pump Magnetically coupled centrifugal pump."}]},{"head":"Adjustments and calibrations droplet size","index":85,"paragraphs":[{"index":1,"size":42,"text":"The atomiser is driven by the high velocity air stream generated by the blower. To meet the required droplet size, the atomiser is fitted with fan blades of which the angle can be adjusted according to the flow rate and the viscosity."},{"index":2,"size":121,"text":"The higher the speed of rotation, the smaller the droplets (fig. 46). A fine blade angle (corresponding to a smaller setting number) gives a high rotational speed (fig. 47). The procedure to change the blade angle is shown by manufacturer in the operator's handbook. It should be followed scrupulously. It should be noted that all the four fan blades must always be set to the same angle. The droplet size can be adjusted from around 45 to 300 microns VMD. For acridid control, a range of droplet size from 30 to 120 microns (for a VMD around 90 microns), is suitable for an acceptable control whereas, a range of 100-175 microns is required for VLV and LV in general agricultural applications."}]},{"head":"flow rate calibration","index":86,"paragraphs":[{"index":1,"size":109,"text":"The flow of chemical from the spray head is controlled by the variable restrictor unit (VRU) in the feed to the atomiser and by the chemical pressure. The knob of the VRU is marked with odd numbers 1 to 13, around the outside and even numbers on the end. VRUs supplied with AU8115 atomisers are fitted with low numbered \"L\" plates with holes 1 to 7 (tab. XX). Therefore the VRU should be set by aligning one of the numbers 1 to 7 with the line on the VRU body. The numbers 8 to 14 are not used on standard VRUs supplied with this atomiser and should be ignored."},{"index":2,"size":23,"text":"table XX. Approximate fl ow rate for AU8115 atomiser fi tted with VRU with low \"L\" plate, in l/min (after Micron Sprayers, 2000)."},{"index":3,"size":133,"text":"Should an unrestricted flow be required, the VRU can be set to the full flow position by turning the thimble to number 7, pulling it back and rotating through 90 degrees until it locks the outward position. This separates the two plates and provides an uninterrupted flow. To release the unit from the full flow position, turn the knob in either direction until the spring returns the selector plate to the normal position. It is advisable to push down on the knob with the palm of the hand to ensure positive seating. Should the unit become blocked after the selecting of the full flow position, it can sometimes be cleared by turning the selector plate backwards and afterwards. Any contamination between the plates will hold the plates apart and give an irregular output."}]},{"head":"General maintenance","index":87,"paragraphs":[{"index":1,"size":47,"text":"After use drain any remaining chemical from the tank. Any unused chemical must be collected in a suitable container for future use or safe disposal. A short length of flexible hose connected to the outlet of drain valve will help to avoid spillage whilst draining the tank."},{"index":2,"size":107,"text":"It is very important that the entire sprayer is flushed out and cleaned after use. Many ULV formulations are corrosive and aggressive and could damage the sprayer if they remain in the system for a prolonged period. flushed out by spraying a suitable solvent for the chemical which has been used. This should be done at the spray site so as to avoid the risk of contamination of an off-target area by dilute chemical. Any solvent remaining in the tank should be drained and disposed of safely. After flushing all external surfaces should be washed with a suitable solvent followed by warm water (whenever possible) and detergent."},{"index":3,"size":19,"text":"Under any circumstances should any chemical or cleaning solvent be left in the sprayer when it is not used."},{"index":4,"size":22,"text":"For more specific maintenance, the supplier provides, with each sprayer, an operator's handbook and catalogue, in which the procedure is thoroughly explained."}]},{"head":"Vehicle-mounted electrical sprayers","index":88,"paragraphs":[{"index":1,"size":147,"text":"These sprayers work under a voltage of 12 volts and a strength of 10 amperes as a maximum. This low requirement makes it possible to connect them to the electric circuit of the vehicle. The originality of these sprayers lies in their relative lightness (about 65 kg), their compactness and small need of energy. They can execute correct spraying even when they are fixed on relative powerless vehicles, provided that they are four wheel drive. Their connection and functioning are simple. The battery is not affected since the sprayer is not often run while the vehicle engine is stopped. These sprayers were proposed for locust control during the late 1980's. They are rustic, low energy users and easy to use, which give advantage for taking advantage in acridid control, especially in preventive locust control where they could be an interesting alternative to the exhaust nozzle sprayer (ENS)."},{"index":2,"size":17,"text":"The basis calibrations of theses sprayers will be described in the next part (part Acridid control treatment)."}]},{"head":"Components the frame and the mast","index":89,"paragraphs":[{"index":1,"size":31,"text":"The sprayer frame is usually made of galvanised or coated steel and it supports a folding mast. This bears the spray head and sometimes allows a little variation of emission height."}]},{"head":"the liquid circuit","index":90,"paragraphs":[{"index":1,"size":37,"text":"The liquid circuit comprises the insecticide tank (and sometimes a flushing tank), the pump, an isolation valve, a drain valve, the flow control mechanism, filters and hose pipes. These materials are more or less resistant to corrosion."}]},{"head":"the electrical circuit","index":91,"paragraphs":[{"index":1,"size":32,"text":"The electrical circuit comprises nylon protected electric cables, the connecting system to the battery and the control box which can be placed in the cab, within the reach of the driver's hand."}]},{"head":"the spray head","index":92,"paragraphs":[{"index":1,"size":20,"text":"The spray head bears a centrifugal-energy nozzle. It uses the electricity provided by the alternator and taped from the battery."}]},{"head":"Installation","index":93,"paragraphs":[{"index":1,"size":91,"text":"The vehicle on which these sprayers are to be mounted, must have an enclosed cab with all its glasses so as to protect the driver from the spray. The sprayers should be positioned on the platform, as far as possible to rear of the vehicle so that, when the mast is extended, the atomiser projects outwards beyond the back of the vehicle. This position also spare a place to additional load of insecticide especially during preventive control operations during which survey and spray alternate and facilitate draining of the insecticide tank."},{"index":2,"size":87,"text":"The sprayer should be rigidly secured to the vehicle via holes drilled in the platform floor using appropriate foot plates, bolts, washers and nuts usually provided by the manufacturer. It should be taken care to avoid the vehicle fuel tank (which is usually beneath the platform), when drilling holes. For a temporary installation, the sprayer can be tied down to the platform with ropes or straps secured around the frame. It should be noted that this installation is possible only when the land is not very rough."},{"index":3,"size":79,"text":"The alternator of the vehicle provides the energy and the connection is made to the battery terminals. The connecting system should be easy to install and easy to disconnect and provided with cutout device. The electrical cables should be protected in a conduit which is resistant to heat and to chemical corrosion. It also should be long enough to allow the control box to be located in the cab of the vehicle, within the reach of the driver's hand."},{"index":4,"size":10,"text":"When installing vehicle-mounted electrical sprayers, special care should be taken:"},{"index":5,"size":96,"text":"• If the sprayer is equipped with a remote control system, the cable should be fed through a clearance hole in the vehicle chassis and the reconnected. When drilling clearance holes, ensure that all sharp edges are removed and covered to prevent premature wearing of the remote cable. When routing the cable to the vehicle cab, make sure that it is not exposed to any sharp edge and avoid any sharp bends. Once the cable has been routed to the cab, reseal all drilled orifices to prevent spray mist or exhaust gases from entering the cab."},{"index":6,"size":24,"text":"• Before proceeding with any operation, the operator should be thoroughly familiar with starting and stopping the machine and with all the operating controls."},{"index":7,"size":18,"text":"• Before full operation, exercise the machine through its full operation sequences from a position of full visibility."}]},{"head":"Ulvamast","index":94,"paragraphs":[{"index":1,"size":121,"text":"The first model of the Ulvamast sprayer (fig. 48) was designed upon the basis of the adaptation of Micron X-15 spray head. Now the manufacturer has developed two versions, V3E and V3M, specifically designed for acridid control by incorporating significant improvements including direct drive atomiser, folding mast with locking extension arm, an increased capacity tank and a standard or electronic in-cab flow controller and atomiser speed. These two new models are equipped with X-9 DD spinning disc atomiser mounted in the mast so that, when it is in use, it protrudes beyond the back of the vehicle. The difference between the two versions is that the V3E is equipped with an electronic controller of the atomiser speed ant the flow rate. "}]},{"head":"adjustment of droplet size","index":95,"paragraphs":[{"index":1,"size":60,"text":"With the V3E model, it is possible to select the atomiser rotational speed from 3,700 to 7,800 rpm by means of the electronic control box. This flexibility is very important for keeping the droplet size within an acceptable range, especially when the viscosity is high or when performing barrier treatment for which high flow rates (around 1.6 l/min) are required."},{"index":2,"size":67,"text":"With the V3M model an increase of the flow rate or in the viscosity results inevitably in an increase of droplet size because there is no way to increase the rotational speed of the atomiser. Nonetheless, even with an output as high as 1.5 l/min the speed is around 6,600 rpm and the VMD estimated at 75 microns which is very good for controlled drift spraying (CDS). "}]},{"head":"Specifi cations of VM sprayer types","index":96,"paragraphs":[]},{"head":"flow rate calibration","index":97,"paragraphs":[{"index":1,"size":45,"text":"With the V3E model, there is a need for frequent flow measurements. This is particularly interesting for stabilizing the flow rate when the viscosity varies with the temperature. Calibration is thus simpler: there are ten preset flow rates on the electronic controller and actual check."},{"index":2,"size":117,"text":"Flow calibration of the V3M model is operated by the combination of an orifice restrictor plate and a progressive control valve. Each sprayer is provided with a set of various restrictor plates (tab. XXI). The flow is controlled via the orifice restrictor plate and adjustable needle valve. Referring to the table, the orifice restrictor plate can be selected according to the required flow rate. If the output obtained is not suitable, then a larger or smaller orifice plate can be used. The full calibration procedure of models of this kind is explained in the following chapter. maintenance Regular maintenance is critical to keep the sprayer in proper working order. Therefore the following operations should be regularly undertaken:"},{"index":3,"size":22,"text":"• Remove pesticide deposits on external surfaces by wiping them down with a tissue soaked in kerosene, diesel oil or soapy water."},{"index":4,"size":15,"text":"• Flush the sprayer through with kerosene or diesel oil, from the auxiliary flushing tank."},{"index":5,"size":17,"text":"restrictor number flow rate (ml/min)   • Make sure that hose pipe connections are secured and leak free."},{"index":6,"size":15,"text":"• Make sure that the atomiser spins freely and the disc is in good condition."},{"index":7,"size":7,"text":"• Never run the pump without liquid."},{"index":8,"size":8,"text":"• Occasionally check and clean the in-line filter."},{"index":9,"size":41,"text":"• During transport between sites, the mast should always be secured in the folded position and the dust cover used to protect the atomiser. Should any malfunction occur, it will be necessary to diagnose the problem: • atomiser does not work:"},{"index":10,"size":20,"text":"-check electrical connections and the fuses in the control box, -check the battery condition, -check if the atomiser spins freely."},{"index":11,"size":9,"text":"• Spray liquid is not emitted from the atomiser:"},{"index":12,"size":31,"text":"-check that the two way valve is in a correct position, -check if the pump works fine, -check for plumbing leak and/or blockage, -check that the in-line filter is not blocked."},{"index":13,"size":6,"text":"• no flow from the pump:"},{"index":14,"size":59,"text":"-check if there is sufficient liquid in the tank, -check that the in-line orifice restrictor is not blocked, -check the electrical connections and fuses in the control box (V3M model only), -check if the in-line filter is not blocked, -check that the pump impeller is not obstructed (motor runs with no flow). This may require disassembly of the pump."}]},{"head":"The exhaust nozzle sprayer","index":98,"paragraphs":[{"index":1,"size":319,"text":"The exhaust nozzle sprayer (ENS) was originally designed for the control of the Desert locust hopper bands by the ultra low volume application of persistent insecticides. Exhaust gases from a vehicle engine are used to shear the spray liquid into 70-90 microns VMD droplets which are projected upwards and then drift downwind. Exhaust gases are directed through a flexible hose to the spray nozzle, the orifice of which is selected to suit the particular vehicle and engine. A pressure gauge with 100 mm diameter, reading 0-1 bar is fitted to a protective cowl and connected to the unit by means of a length of hose. The gauge and the cowl are usually fitted to the vehi-cle so that the operator can check the pressure all the time. A safety valve prevents excessive back pressure which may damage the engine. Pressure of the exhaust gases is also used to force the spray liquid through the nozzle. The sprayer is operated so that a wind across the line of travel takes the 70-90 microns droplets downwind away from the vehicle. Swath widths vary with wind speed. For example, with 10-15 km/h winds, at 1.2 l/min output and vehicle speed of 10 km/h, the application rate is 0.3 l/ha over 300 m swath which is suitable for the low acting insecticides for barrier treatments. The sprayer ca be fitted to most types of four wheel drive vehicles used by locust control operators. Whatever vehicle used, it should have a double-ratio gear box and an enclosed cab for the driver to be protected from the insecticide spray. The ENS is the cheapest and simplest vehicle-mounted sprayer. However calibrations are very difficult to achieve and stabilize. Besides, recent machines are equipped with nozzles that produces a poorer droplet spectrum than the ones on the old machines. These flaws and the difficulty of spare part supply led locust operators to prefer the vehicle-mounted electrical sprayers."}]},{"head":"Aerial equipment","index":99,"paragraphs":[]},{"head":"Historical background","index":100,"paragraphs":[{"index":1,"size":315,"text":"Right from the beginning, aviation pioneers tried to use aircraft in agriculture. Considered as the father of agricultural aviation, Alfred Zimmerman (1876-1964) was granted a patent for the use of aircraft in the control of insect pests in forestry management. The real start of agricultural aviation was during the 1930's when the aircrafts used for aerial application work came from the military surplus of the First World War. It was not until the 1950's that commercial aircrafts specially designed for aerial applications came into being. Through advances in chemical technology, a more economic use of aircraft was made possible, because small quantities of chemicals were successfully used (Quantick, 1985). Now agricultural aviation is practised on all continents, numbering more than 40,000 aircrafts all over the world. In locust control, the first aerial low volume (LV) trials were realized with aircrafts equipped with boom-and-hydraulic nozzle during the late 1940's. But the use of aircraft in locust control was boosted with the introduction of the first Micronair by the company Britten Norman. It was then possible to produce droplets fine enough to allow drift spraying. During the 1986-1989 plague, aerial application covered approximately 14 million hectares in Africa and the Near East and 4 million hectares during 1993 in Asia and Africa. The importance of aerial applications in this domain depends upon the acridid situation which is a consequence of outbreaks and recession periods. From a strictly financial point of view, aerial applications are only justified when vast areas are involved. Efficiency in these conditions is from five to ten times higher than with ground applications. But in locust control aerial interventions are often required even when areas really infested are relatively small, especially when early action is more important than financial considerations. However, it should be noted that the availability of logistic support on the ground is a key factor in the cost of the operation."}]},{"head":"Criteria of acridid control aircrafts","index":101,"paragraphs":[{"index":1,"size":238,"text":"Aircrafts used in acridid control are usually confronted with very challenging atmospheric conditions. The engine, the aircraft structure and the spraying system must be robust and simple, so that some repairs could be done easily by the pilot himself. Airplanes should have a good manoeuvrability, since they must fly at low level with relatively low speed. Therefore it is essential that they have sufficient climbing capabilities. The lateral stability at the stall should be such that if the aeroplanes is in a flat skidding turn and the control stick is eased full back, the aeroplanes will continue to turn under control and will not suddenly increase its bank and start into a spin or flick the other way and spin as with some aeroplanes in use in application work (Quantick, 1985). Atmospheric conditions such as high air temperature may affect engine efficiency consequently climbing performance of the aircraft. It must be noted that nominal specifications (tab. XXIV) are given for standard atmospheric condition i.e. a temperature of 15° C and a pressure of 1,013 hpa at sea level. A rise of temperature and altitude of operating site may result in a decrease of aircraft capabilities. It is therefore wise to accept the pilot's decision when he refuses to board some more passengers for a survey flight even though there are still some unoccupied seats. Fuel and spray equipment must be considered as being a part of the cargo."},{"index":2,"size":22,"text":"All elements should contribute to ensure the security and saving of running costs. The main desirable characteristics of acridid control aircrafts are:"},{"index":3,"size":19,"text":"• To be able of to lad a cargo up to 35 to 40 % of their gross weight."},{"index":4,"size":29,"text":"• To be capable of getting over a 15 m high obstacle after taking off from a bare earth strip of 400 m in standard air at sea level."},{"index":5,"size":7,"text":"• To have a high climbing speed."},{"index":6,"size":9,"text":"• To have a low stall speed (65-100 km/h)."},{"index":7,"size":15,"text":"• To be able of flying at low altitude with a 130-200 km/h operating speed."},{"index":8,"size":52,"text":"• To be able to turn sharply at low altitude. • To own a cockpit which allow a good view forward and own for clearance of any obstacle such as fences, trees and wires. A good view ahead over the nose is necessary for taxiing in small unprepared an temporary air strip."},{"index":9,"size":72,"text":"• The design of the forward fuselage and the cabin structure should resist nominal crash loads as well as flight and landing loads. Aircraft structures should absorb energy by progressive by progressive collapse. Shoulder harness, safety belts, seats and anchorages should be comfortable but also of enough strength to resist failure up to the point of cabin collapse. The cabin should be pressurised so as to avoid poisoning the pilot by pesticides."},{"index":10,"size":60,"text":"• The hopper is located ahead of the cabin, so that it remains within the limits of the centre of gravity during take off. The hopper should have a large door located to allow easy and quick loading either by hand or by machine. The hopper should by fitted with a device for jettisoning the load in case of emergency."},{"index":11,"size":19,"text":"• Fuel tanks should be located in or on, the wings far away from the cabin and the engine."},{"index":12,"size":68,"text":"• It is extremely important that the aircraft be inspected and maintained easily and repaired quickly in order to keep it on operation without loss of time, especially during intensive locust control campaigns. All control linkages and critical parts should be visible and easily inspected. Materials and paints should resist corrosion of formulations. • The cooling system should be designed large enough to avoid excessive rise in temperature."},{"index":13,"size":52,"text":"• In acridid control areas, air often carries a lot of dust. Aircraft should therefore be equipped with an efficient anti-dust system. The engine should be well protected by judicious location of the carburettor air inlet, the use of ample air filters and, under adverse conditions, by the use of fuel-flow filters.  "}]},{"head":"Aircrafts used in acridid control","index":102,"paragraphs":[{"index":1,"size":68,"text":"Aircrafts which can be used in acridid control depend on tactic and the importance of target zones. The use of helicopters is increasing thanks to a relative decrease of their cost-in-use and the possibility of using them in areas without airstrips. The attempts to introduce ultra light aeroplanes, in the Sahelian area, were not satisfactory so far, because they are too fragile against sudden and frequent air turbulences."}]},{"head":"Heavy cargo aeroplanes","index":103,"paragraphs":[{"index":1,"size":71,"text":"This type of aeroplane can carry a cargo of several tons, over a 500 km distance. Their size does not allow them to land in short and unprepared airstrips, frequently used in acridid control. Their long range compensates for this disadvantage but their cost-in-use is very high. Actually, they are useful only in a few cases, when vast areas over hundreds of thousand hectares lying together are to be treated rapidly."}]},{"head":"Medium sized and light aeroplanes","index":104,"paragraphs":[{"index":1,"size":105,"text":"Aeroplanes of this type are frequently utilized since they are reliable from a security point of view and the improvement of their productivity. Aeroplanes designed specifically for aerial applications belong to this category. They are rustic and capable of taking off and landing on short and rough runways; their taking off distance is short (200-400 m). Many brands and models were recently used in acridid control (tab. XXIV). The most commonly used among light aeroplanes are Piper PA 25 Pawnee, Cessna Ag Truck and Ag Wagon. Among medium-sized aeroplanes recently used in acridid control are Britten Norman Islander, Antonov AN2, Turbo Trush, Grumman Air Tractor."}]},{"head":"Helicopters","index":105,"paragraphs":[{"index":1,"size":132,"text":"Helicopters have a reputation of being expensive to use. However, their recent use in locust control showed that this assessment should be mitigated in favour of helicopters for several reasons. Modern equipment with various specifications make it possible to select the most efficient solution and therefore to decrease the costs. Besides, helicopter are ideal to intervene on locust infestations located in an area hard to get by ground. The use of helicopters is critical when it is required to combine survey and treatment on a given area. It is actually possible to land on a precise spot and scout around. It is also possible to perform preventive surveys on vast areas within the range of the helicopter (tab. XXV), mark out areas to be treated by aeroplanes and perform after treatment checks."},{"index":2,"size":86,"text":"For acridid control in the Sahelian countries, helicopters are often justified because they can be used either directly for treatment or for supporting large scale interventions by aeroplanes. Their potentialities are fully utilised when their use is planned long in advance and fuels and lubricants made available on key spots before the beginning of the monsoon. Advantages of helicopters are fully expressed by the possibility of making direct contacts with farmers and shepherds who may help to locate swarms, egg fields, hopper bands or grasshopper infestations."},{"index":3,"size":22,"text":"Beside their professional skill, crews should have good adaptability to Saharan-Sahelian conditions and human qualities for making useful contact with local populations."},{"index":4,"size":17,"text":"table XXv. Specifi cations of some helicopters used in pest control (after Castel, 1982 andChaussepied, p.c. 1990)."}]},{"head":"Aerial spraying equipment","index":106,"paragraphs":[{"index":1,"size":44,"text":"In most cases of acridid control, applications involve the use of ULV formulations. Volume of application generally varies from 0.5 to 3 l per ha, although 1 l/ha is the most frequently used volume. The equipment described below is basically designed for ULV applications."}]},{"head":"Spray gear","index":107,"paragraphs":[{"index":1,"size":27,"text":"Spray gear (fig. 50) is the name given to the equipment through which the liquid flows from its loading to the spray head. The main components are:"}]},{"head":"Chemical tank or hopper","index":108,"paragraphs":[{"index":1,"size":145,"text":"The hopper capacity varies between 300 and 700 l for light size and 800 to 2,000 l medium-sized aircrafts. They are, most often, constructed from fibreglass so that they may be repaired in the spot.  For security reasons, the hopper is situated inside the fuselage, between the cockpit and the engine. Thus, albeit aircraft evolution in the air the cargo weight remains within the limits of the centre of gravity. The jettisoning device should be designed so that the load can be released within 5 seconds. Belly tank stowed to the underside of the fuselage or pods mounted on standard underwing pylons could be jettisoned, with their load, in an emergency. Some helicopters are equipped with twin tanks mounted on each side (fig. 51). The tanks communicate with each other so as to maintain the balance between lateral weights with regards to centre of gravity."}]},{"head":"Filters","index":109,"paragraphs":[{"index":1,"size":102,"text":"It is critical that the liquid be filtered before it flows to the spraying system because solid particles may agglutinate and plug check valves, nozzle filters or the flow regulator. If the filtration is deficient, the spray will be highly affected. This is the reason why several filters are placed along the circuit of liquid. A wide basket filter is located at the filling point. The liquid flows through a second filter just before or, according to various systems, after the pump. A final Spraying Equipment 75 filter is sometimes placed just before spray head, as is the case with hydraulic nozzles."},{"index":2,"size":28,"text":"it is highly recommended to regularly clean the filters so as to avoid breakdowns which may have serious consequences. therefore they should be easy to reach and clean."}]},{"head":"Pumps","index":110,"paragraphs":[{"index":1,"size":135,"text":"Every spray system is equipped with a pump which supplies the liquid, under a given pressure, to the spray boom and atomising devices. The working pressure usually varies from 1.5 to 5.6 bars. The efficiency is 25 % for centrifugal pumps and 20 % for gear pumps. Pumps should be powerful enough to ensure the maximum output required and provides agitation of liquid in the tank by continuous re-circulation. There are several types of pumps, each having advantages and disadvantages: a. centrifugal pumps (fig. 52 and 53) They are suitable for large volume (up to 550 l/min) at low pressure. Viscous liquid can be pumped. The volume of liquid emitted decreases rapidly when the pressure exceeds 2.5-3.0 bars. If the outlet is closed when the pump is running, the pressure rises slightly without causing damage."},{"index":2,"size":41,"text":"These self-priming pumps have to be located at the lowest place of the circuit so as to be primed even when there is a little amount of liquid in the tank. Centrifugal pumps usually run at high rotational speed (4,000 rpm)."}]},{"head":"B. gear pumps","index":111,"paragraphs":[{"index":1,"size":41,"text":"They consist of two meshed gears, where one of them is connected to the drive source (fig. 54). The liquid is drawn between the gear teeth which rotate in opposite directions. The teeth are coated against corrosion with a protective layer."},{"index":2,"size":40,"text":"Gear pumps are fragile, thus they are usually equipped with a relief valve to prevent damage which may be caused by excessive rise in pressure. Output might be adjusted from 5 to 200 l/min with a pressure of 7 bars. "}]},{"head":"c. roller pumps","index":112,"paragraphs":[{"index":1,"size":46,"text":"Inside the eccentric case of the pump, a rotor with five to eight slots, rotates (fig. 55). In each slot a roller rotates while moving in and out to catch and eject the liquid. The rollers are usually protected against corrosion by a layer of Teflon."},{"index":2,"size":31,"text":"Roller pumps are normally designed to rotate at 1,000 rpm and an output from 20 to 140 l/min under a pressure of 20 bars. The flow varies with the rotational speed. "}]},{"head":"Pump drive","index":113,"paragraphs":[{"index":1,"size":14,"text":"The driving system of pumps in aircraft partially depends on the type of aircraft."}]},{"head":"a. air driven pump","index":114,"paragraphs":[{"index":1,"size":81,"text":"This system (fig. 56) is simple and relatively cheap. The energy does not depend directly upon the aircraft engine. In the other hand, it is sensitive to airspeed and the flow rate calibration cannot be performed on the ground. Yet, a propeller with adjustable plastic blades is preferable (Castel, 1982). It is important to provide a brake to stop pumping during manoeuvring flights. Advantages of a pump with adjustable propeller blades (Castel, 1982): • It is lighter than fixed metallic blades."},{"index":2,"size":44,"text":"• It is possible to adjust the output so as to avoid an important back flow to the tank (small output for ULV). This calibration is made by setting the angle of the blades. Wider the angle, lower the rotational speed of the pump."},{"index":3,"size":15,"text":"• It is possible to use 3 to 6 blades according to the power required."},{"index":4,"size":19,"text":"• It is not required to dismantle the propeller before convey flights; to this end, blades should be feathered. "}]},{"head":"B. hydraulically-driven pump","index":115,"paragraphs":[{"index":1,"size":28,"text":"This type of energy transfer is rather common; it is steady and easy to repair. Its main disadvantage is being heavy. It is mainly used to equip helicopters."}]},{"head":"c. mechanically-driven pump","index":116,"paragraphs":[{"index":1,"size":45,"text":"This pump is in direct drive by the aircraft engine. It is usually installed in helicopters but it is difficult to set them in older aircrafts. However they are light, simple and economic. These advantages argues for the extension of their use in new aircrafts."}]},{"head":"d. electrically-driven pump","index":117,"paragraphs":[{"index":1,"size":53,"text":"The efficiency of electrically-driven pumps is good when the power is below 1.5 HP. Above this, powering the electrical system on board becomes expensive. Electrical sources of energy are used in helicopters for ULV and VLV spraying system. New electrical equipment is well-designed so that they are not affected by excessive high temperatures."}]},{"head":"Pressure and flow regulators","index":118,"paragraphs":[{"index":1,"size":94,"text":"Basically they are designed on the principle of a valve with a progressive closing of the back flow to the tank. Closing the valve induces a pressure rise in the system. When a large amount of liquid returns to the tank, the pressure decreases in the circuit which reduces the flow of liquid to the spray boom. By adjusting the flow of liquid returning to the tank, the spray system is protected against excessive pressure which may be detrimental. When the spray is stopped, a bypass allows the liquid to return to the tank. "}]},{"head":"No spraying","index":119,"paragraphs":[]},{"head":"Spraying","index":120,"paragraphs":[{"index":1,"size":2,"text":"Spraying Equipment"}]},{"head":"79","index":121,"paragraphs":[]},{"head":"B. three way valve","index":122,"paragraphs":[{"index":1,"size":124,"text":"It is basically a three way sphere. It swivels round so that it lets a flow of liquid, more or less important, towards the spray boom. The bearing and the sphere are Teflon-coated to protect against corrosion and waterproofness. In a bypass circuit, a screw modulates the amount of liquid which returns to the tank. This bypass opens onto a Venturi where the liquid speeds up (fig. 58 and 59). When the pilot closes the valve to stop the spray, a pressure drop occurs in the boom and immediately stops the flow of liquid and hence emission of droplets. A three way valve ensures a good and progressive flow rate calibration from \"0\" to the maximum possibilities of the pump and the spray system. "}]},{"head":"Manometer (pressure gauge)","index":123,"paragraphs":[{"index":1,"size":74,"text":"The pressure at which the spray is emitted is an important factor in the spray quality. Pressure reflects the state of liquid flow inside the spray system. Hence, pressure variation should be monitored in the cabin so that the pilot may constantly see what is going on in the circuit. Therefore the manometer should be easily visible to the pilot. Before taking off, the pilot should be sure that the manometer is working properly."},{"index":2,"size":14,"text":"The needle of the manometer should return to \"0\" when the system is switched "}]},{"head":"Spray boom","index":124,"paragraphs":[{"index":1,"size":62,"text":"In fixed wing aircrafts the spray boom is generally as long as the wingspan. It is generally fixed at the back of the wing but actually this depends upon the wing position in relation to the fuselage (above or below the wings). The booms is often a hollow tube or streamline cross-section, made of stainless steel, brass or aluminium alloy (fig. 61)."},{"index":2,"size":60,"text":"On helicopters, the boom is smaller than the rotor, with a maximum of 15 m. It is composed of three sections where the central third is placed at the back under the turbine. The boom should be able to be dismantled easily and rapidly or folded up, so as to enhance the efficiency of the helicopter (fig. 62 and 63)."}]},{"head":"Atomising devices","index":125,"paragraphs":[{"index":1,"size":48,"text":"Although there are still some boom-and-nozzle gears, the primary airborne equipment used in acridid utilize rotating atomisers. Hydraulic energy nozzles are less frequently used in acridid control because droplets are not fine enough to suit ULV. However for LV and VLV spray technique, the boom-and-nozzle gear is acceptable. "}]},{"head":"Hydraulic nozzles","index":126,"paragraphs":[{"index":1,"size":41,"text":"The most commonly used are fan nozzles and cone nozzles. Spray boom comprises 20 to 50 nozzles, 16.5 to 33 cm from each other so as to ensure an uniform spray even when some of them are blocked up (fig. 51)."},{"index":2,"size":68,"text":"For LV and VLV applications, cone nozzles are commonly used (fig. 9). Flat nozzles, more suitable for applications of herbicides, are not used in acridid control. Each nozzle is equipped with an anti-drip diaphragm system, as it is important that no chemical leaks from the system when the pressure drops (fig. 64). When the pump is shut or the valve is closed, the pressure drops inside the boom."},{"index":3,"size":19,"text":"Although the diaphragm is coated with a thin Teflon layer, frequent checks are required to ensure its correct functioning."},{"index":4,"size":9,"text":"figure 64. Cutaway of check valve (after Shell, 1983)."},{"index":5,"size":177,"text":"The output depends upon the working pressure, the number of the nozzles and the diameter of the orifice. To alter the output, it is required to modify the number of nozzles in combination with the orifice diameter. However it should be noted that the output of a nozzle is proportional to the square root of the pressure; so doubling the working pressure only increases output by 40%. Therefore basic adjustment should be achieved by altering the number and/or the size of the nozzles (Quantick, 1985). Droplet size varies with the working pressure, the type of nozzle and their orifice and the nozzle orientation. Thus when nozzles are pointed backwards, the spray and slipstream are travelling at similar velocities and there will be little shear at the air/liquid interface causing production of large drops. If nozzles are pointed forward into the slipstream, the difference in relative velocities is maximized and the increased shear produces fine droplets (fig. 10). Despite this possible adjustment, droplet spectrum produced with boom-and-hydraulic-nozzles is too coarse to meet the requirement of optimal ULV technique."},{"index":6,"size":58,"text":"Where aircrafts are frequently used in application of herbicides, for the purpose of reducing the size and weight of spray systems, it is possible to fix spray boom hydraulic nozzles and atomiser as well. Thus it is possible to use alternatively the former to spray VLV and LV aqueous formulations and the latter to spray ULV oily formulations."}]},{"head":"Rotary atomisers","index":127,"paragraphs":[{"index":1,"size":66,"text":"These droplet generators, furthered the development of aerial ULV applications. Droplet generation is realised by high rotational speed of a spray head. Droplet spectrum is narrow and fine, suitable for good quality ULV applications allowing large swath width. Adjustment of droplet size is realised by monitoring the rotational speed of the atomiser. At present, most of aircrafts used in acridid control are equipped with rotary atomisers."},{"index":2,"size":20,"text":"Atomisers may be electrically-driven (Airbi, Beecomist or Micronair) or by a hydraulic system (Micronair) or propeller-driven Micronair and Curtis ASC-Line)."},{"index":3,"size":39,"text":"Airplanes are usually equipped with propeller-driven system systems while helicopters are equipped with hydraulic or electric systems. Many models of several brands are proposed. The most common are Micronair rotating cages, Curtis Agri-Line ASC system and Beecomist spray head."}]},{"head":"a. micronair rotating cages","index":128,"paragraphs":[{"index":1,"size":232,"text":"Micronair rotating cages are most commonly used in acridid control. The atomiser consists of a cylindrical gauze rotating around a fixed spindle which is attached to a mounting brackets on the aircrafts. Several variants are available. They can meet requirements of different aerial equipment. aU4000 AU4000 rotating cage (fig. 16) is robust and not vulnerable to loss of balance. This model has a good distribution over the gauze and capable of releasing sprays with fine droplets and narrow spectrum. The output varies from 0.3 to about 23 l/min. So, it is suitable in acridid control. aU5000 This mini-cage was formerly developed for ground airblast sprayers. It is now extensively used both in aircrafts and helicopters. It is similar to AU4000 but lighter. Thus, it is possible to fix 10 units instead of standard boom-and-hydraulicnozzle. Each AU5000 atomiser can handle a flow up to 23 litres/minute which enables the same installation to be used for a range of output rates from ULV to conventional applications at 20-50 litres/hectare. aU7000 It was developed primarily for ground airblast sprayers. It is similar to AU5000 but smaller. It is driven by four adjustable fan blades to provide additional power even at slower air speeds. It is well suited for microlight aircrafts, where weight is of great importance. The output can be adjusted from 0.2 to 6 litres/minute under a working pressure of 10 to 20 psi."},{"index":2,"size":89,"text":"Frequently, four atomisers are fitted to a light aircraft such as a Piper Pawnee PA 25 (fig. 65). With new models, more compact and lighter, it is possible to adapt the spray system according to the aircraft type and the tactic needs. Thus it may be possible to shorten the distance between spray heads for fixing a greater number on the same spray boom. The Micronair system is composed of a cage, fan blades, a check valve, a flow metre and a flow monitoring system (fig. 66 and 67).  "}]},{"head":"the cage","index":129,"paragraphs":[{"index":1,"size":286,"text":"The cage consists of a cylindrical gauze rotating around a fixed spindle which is attached to a mounting bracket on the aircraft. Power is supplied from the air flow through five balanced delrin blades clamped in a hub, which also carries the gauze and the bearing assembly. The pitch of the blades is adjustable and this is used as the means of controlling rotational speed of the cage which varies from 2,000 to 14,000 rpm. The gauze is constructed of anti-corrosive alloy soldered to alloy diaphragm plate. In case of damage or any conditions which may cause it to run out of balance, it must never be repaired in the field as it must be dynamically balanced after repair. Therefore it is preferably to replace the damaged cage by a new one and send it to the manufacturer for repair. Chemical is introduced by the hollow spindle through a rotating deflector that distributes the liquid along the diffuser tube, which also rotates. An initial break up of the liquid is achieved here before it reaches the gauze. Atomisation is finally completed as the liquid is thrown clear of the gauze. The speed of rotation determines the droplet size. electric brake An hydraulically or electrically-operated brake is fitted to the mounting bracket so as to stop the atomiser in the event of an emergency or during the ferry flying. The brake consists of a solenoid and friction lining mounted in the atomiser attachment block and a pole plate joined to the front plate of the hub assembly by means of a leaf spring. When the solenoid is energized, the pole plate is attracted to the face carrying the friction lining and the resulting torque stops the atomiser."},{"index":2,"size":107,"text":"The electric brake is self adjusting and does not require any regular maintenance in service. Slight wear of the pole and the plate and solenoid assembly is normal, these parts must, however, be replaced if the wear becomes excessive and the efficiency of the brake is reduced. except in emergency (a broken fan blade), the brake should never be operated when atomisers are on rotation, because there is a high risk of damaging brake discs. it is preferably to brake them on the ground and release them before starting to spray. at the end of spraying they should be left rotating until complete stop of the aircraft."}]},{"head":"diaphragm check valve","index":130,"paragraphs":[{"index":1,"size":128,"text":"The diaphragm (fig. 68) is designed to eliminate dribble from the atomiser after the spray is shut off. The unit is not a substitute replacement for the secondary shut off valve on the spindle inside the atomiser and is intended to hold back any static pressure in the spray system which could lead to leakage. The check valve is constructed from chemical resistant materials; the diaphragm being viton reinforced operating on stainless steel seat to ensure resistance to corrosive chemicals. Normally, the diaphragm check valve requires very little maintenance. However, it should be checked periodically, since chemical formulations are frequently changing and it is possible that the viton diaphragm may be attacked by unusual chemicals. If this happens replace with the correct spare part or advise the manufacturer."}]},{"head":"variable restrictor unit (vrU)","index":131,"paragraphs":[{"index":1,"size":213,"text":"The variable restrictor unit (fig. 69) controls the flow of chemical to each atomiser (fig. 66 and 67) by means of an orifice plate with a number of holes of different drilled around its periphery. The orifice plate lies against a selector plate which has a single hole and attached by a shaft to a calibrated thimble at the end of the unit. The hole in the selector plate can be set to align with any one of the holes in the orifice plate, thus controlling the chemical flow according to the hole size. The thimble is made to \"click\" into the appropriate position by means of a spring in the VRU body which engages in groves inside the thimble. This ensure that the hole in the orifice plate is aligned with the hole on the selector plate. The posi- The knob of the VRU is marked with odd numbers 1-13 and even numbers 2-14. These numbers (tab. XXVI and fig. 70) correspond to the holes sizes in the \"O\" (odd) and \"E\" (even). The orifice diameters varies from 0.77 to 6.35 mm. Thus, for AU4000 atomisers, the flow rate varies from 0.34 to 21 l/min. A number of alternative plates can, however, be supplied on request to suit special needs (tab. XXVII)."},{"index":2,"size":20,"text":"table XXvi. Flow from VRU standard odd number plate and with optional even number plate (after Castel, 1982 andMicronair, 1992)."}]},{"head":"plate","index":132,"paragraphs":[{"index":1,"size":41,"text":"Orifi ce aU4000 aU5000 no ø (mm) 30 psi 40 psi 50 psi 20 psi 30 psi 40 psi  For example, by turning the knob to the pair of numbers 13 and 6, one of the two following cases is possible:"},{"index":2,"size":16,"text":"• If the orifice plate \"E\" is fixed, then the orifice n o 6 is selected."},{"index":3,"size":16,"text":"• If the orifice plate \"O\" is fixed, then the orifice n o 13 is selected."},{"index":4,"size":57,"text":"table XXvii. Alternative VRU orifi ce plates and their manufacturer references. The fl ow must always enter the side of the VRU. This forces the selector plate against the orifi ce plate. Should the VRU be incorrectly installed with the chemical entering the end, the plates would be forced apart and an erratic fl ow would result."},{"index":5,"size":12,"text":"During calibration the viscosity of the formulation should be taken into account."},{"index":6,"size":55,"text":"The influence of this factor on the flow variation is as important as pressure varia- In the Micronair system the working pressure varies from 20 to 50 psi (around 1.4 to 3.5 bars). Its influence on the flow remains within these limits. In contrast to hydraulic energy nozzle, the pressure does not influence droplet size."},{"index":7,"size":24,"text":"The total output from the aircraft in litres per minute is divided by the number of atomizers to determine the output from each atomizer."},{"index":8,"size":90,"text":"Each VRU should be checked and cleaned periodically. Should it be necessary to dismantle the unit, follow manufacturer's instructions. fan blades and droplet size Micronair atomisers are supplied with different fan blades according to different flying speeds of aircrafts (fig. 71), suitable for air speeds between 75 and 150 mph (120-240 km/h). For faster aircrafts, it may be necessary to shorten the blades, provided they keep a uniform size and the weight (a variation in weight less than 0.5 g is acceptable). Slower aircrafts and helicopters require longer fan blades."},{"index":9,"size":7,"text":"The manufacturer can supply them on demand."},{"index":10,"size":6,"text":"A: dry; B: water (20 l/min)."},{"index":11,"size":35,"text":"figure 71. Graph of rotational speed vs air speed for AU4000 fi tted with CBP289/2 with 3.7\" standard blade (after Micronair, 1991). A check should always be carried out with the actual chemical being used."}]},{"head":"Locust Control Handbook","index":133,"paragraphs":[{"index":1,"size":28,"text":"A: dry; B: water (20 l/min). figure 72. Graph of rotational speed vs air speed for AU4000 fi tted with CBP252/2 with 4.9\" standard blade (after Micronair, 1991)."},{"index":2,"size":92,"text":"Micronair atomisers are designed to produce a uniform droplet spectrum as possible, with a VMD less than 100 microns. The mean size of droplets produced by an atomiser is determined by the rotational speed of the gauze (fig. 73). As the gauze is turned by the fan blades in the airstream, the speed of rotation is controlled by both air speed and the blade angle. The air speed is determined by the type of aircraft and the spraying operations, hence the droplet size is controlled by the setting of the fan blades."},{"index":3,"size":216,"text":"Having established the correct rpm, it is necessary to determine the appropriate blade angle setting to produce this rpm at the operating airspeed (fig. 71 and 72). For AU4000, the angle is shown in degrees over the range of 25-45 degrees, which is the normal operating range. These are marked dry and 20 l/min, corresponding to an atomiser spraying no (or very little) chemical and 20 l/min respectively. An increase in the volume of chemical flowing through the atomiser results in the atomiser slowing down. Greater power is required to break up the liquid into fine droplets. Consequently, it is necessary to set the fan blades to a smaller angle to speed up the fan to the required level when spraying higher volumes (fig. 74). The viscosity of the liquid being sprayed also has an influence on the rotational speed on the atomisers. Viscous formulations tend to reduce the rotational speed and hence to produce larger droplets. In general, ULV formulations will tend to form larger droplets than water-based LV formulations at the same rotational speed. Therefore, when spraying viscous chemicals or high outputs it is required to raise the power of atomisers to keep a relevant rotational speed. it should be noted that there is a maximum continuous rotational speed for each type of atomiser."}]},{"head":"application monitor","index":134,"paragraphs":[{"index":1,"size":117,"text":"The application monitor is a complete monitoring system for any spray aircraft (fig. 75). Chemical flow is measured by a flowmeter turbine, which is connected to a microprocessor-based electronic unit. This takes the chemical flow rate, together with the swath width and ground speed of the aircraft and computes all the basic parameters of the spray operation. The electronic unit incorporates a liquid crystal display and a touch keyboard. The key board is used to select the function shown on the display. The application monitor can be calibrated to work with either of two flowmeter turbines. It is also programmed to operate with a printer, which may help to keep a daily record of every spray job."}]},{"head":"rpm indicator (tachymeter)","index":135,"paragraphs":[{"index":1,"size":42,"text":"Given the close relationship between rotational speed of the atomiser and droplet size, it is very important that the pilot instantly visualize this datum. The application monitor may be used to measure the rotational speed of each of up to 10 atomisers."}]},{"head":"checks and maintenance","index":136,"paragraphs":[{"index":1,"size":69,"text":"Normally the manufacturer provides an operator's handbook, corresponding to the installed system. It is of paramount importance to carefully read the entire handbook and follow its recommendations, regarding installation, operating procedures and maintenance. During intensive campaigns, it is necessary to thoroughly check all parts of the spray system before starting operations in every site and daily after the last morning flight. The main key points for regular checking are:"},{"index":2,"size":13,"text":"• Check the functioning of atomiser brakes and all atomisers before each flight."},{"index":3,"size":72,"text":"• Ensure that all atomisers run smoothly. The only friction should be the small amount of drag from the V-ring seal. Do not continue to operate the atomizer if it does not run smoothly. Remove the unit, dismantle the bearing assembly and check the bearing and fits and clearances; particularly the two matched bearing spacers which should be identical lengths. Return the unit to the manufacturer if the solution cannot be found."},{"index":4,"size":47,"text":"• Check that the spindle retaining the nut is tight and wire locked. Under no circumstances should the atomiser be operated if the nut is slack. If the atomiser is used with a loose nut, it is almost certain that the bearing or spacers will be damaged."},{"index":5,"size":23,"text":"• If greased bearings are installed, ensure that they are greased regularly but not excessively. Overgreasing can cause heating and destroy the bearings."},{"index":6,"size":36,"text":"• Inspect all gauzes for chemical deposits, damage or any conditions which may cause it to run out of balance. Gauzes should never be repaired in the field as they must be dynamically balanced after repair."},{"index":7,"size":68,"text":"• Check that all fan blades are in good condition and are set to the correct angle for the work being undertaken. Replace any damaged blades and ensure that the clamp rings securing bolts are not overt-tightened. If the bolts are correctly tightened, it should be just possible to move the blades by hand. The gap between the clamp ring and the hub must not be completely closed."},{"index":8,"size":17,"text":"• Inspect the diaphragm check valve for chemical leakage. This indicates a damaged or wrongly installed diaphragm."},{"index":9,"size":23,"text":"• Ensure that all VRUs are correctly secured, set to the appropriate number and check that there is no evidence of chemical leakage."},{"index":10,"size":35,"text":"• Check application monitor (if fitted) to be sure it is functioning correctly. Verify the accuracy of the reading by checking the volume of chemical sprayed against the actual area sprayed and the spray time."},{"index":11,"size":58,"text":"• Should any vibration be noticed from the boom or atomisers, do not continue to operate. Reduce airspeed, apply atomiser brakes and land as soon as possible. Check for loose attachments, worn bearings, out of balance gauzes and insure all the blade settings are correct. Check that the hub, clamp, ring and gauze are correctly assembled and aligned."}]},{"head":"B. curtis agri-Line aSc System aSc-a10 Spray head","index":137,"paragraphs":[{"index":1,"size":67,"text":"The ASC (Advanced Spectrum Controller) was designed in the United States, to operate at airspeeds which exceed 360 km/h (aircrafts) while continuing to excel in speeds as low as 55 km/h (small helicopters). It can deliver a wide range of outputs from conventional low volume to ULV spraying at 1 l/ha. The cage is fitted with graphite reinforced adjustable blade and heavy duty sealed bearing (fig. 17)."},{"index":2,"size":73,"text":"So far ten Agri-Line System is not commonly used for acridid control. But considering the design features asserted by the manufacturer, the ASC System is likely to be suitable for acridid control. Therefore we think that it deserves a place within equipment proposed for aerial applications in acridid control. Four models of ASC rotary atomisers are available: wind-driven for fixed wing, wind-driven for helicopters and electric-powered 12 volt DC and 24 volt DC."},{"index":3,"size":6,"text":"figure 76. Curtis Dyna-Fog ASC-A20 cage."}]},{"head":"aSc-a20 spray head","index":138,"paragraphs":[{"index":1,"size":106,"text":"It is electrically-powered. Feature blushless CD motor, double balanced with heavy duty sealed bearing. It is available in 12 and 24 volt version. The ASC-A20 is designed to equip helicopters. (fig. 76). The atomiser weight is 1.7 kg each. The A20 atomiser produces a very tight droplet spectrum that is suitable for controlled drift spraying. Since this spray head uses blushless motor technology and a closed loop motor control circuit, atomiser speed can be accurately controlled so that virtually no variation is present during operation. The normal operating speed of ASC-A20 is 25,000 rpm and each atomiser can be independently adjusted to produce required droplet spectrum."}]},{"head":"c. Beecomist spray head","index":139,"paragraphs":[{"index":1,"size":81,"text":"The Beecomist spray head is manufactured by Beeco Products Company (USA). It is very common in the USA and is frequently mounted on helicopters in Europe, Africa and Near East. It is a rotating stainless porous cylinder (fig. 77). Power is supplied by a hydraulic or electric motor which runs under 12 or 24 volts and a strength of 10 to 20 amperes. In this case the generator should be capable of providing a power of 100 amperes at full charge."},{"index":2,"size":20,"text":"Droplet size varies with the rotational speed of the atomiser. A filter and a check valve are required up stream."},{"index":3,"size":27,"text":"The atomizers should be fixed on the boom so that they form a 9 to 10 degrees angle with regards to the horizontal setting of the boom."}]},{"head":"d. airbi spray head","index":140,"paragraphs":[{"index":1,"size":103,"text":"The first version realised by the French company Airbi was made of a rotating cylinder fitted with wire brush. Droplet spectrum was acceptable but the brush favours crystallization of chemicals. Now the brush is replaced by a perforated cylinder (fig. 78) The spray head, including the motor, weighs 1,140 grams. Liquid is introduced through a distributor and, under centrifugal force it is evenly distributed along the cylinder. The assembly motor and cylinder is compact, watertight and tropicalized. Rotational speed varies from 2,000 to 12,000 rpm and flow rate from 0,250 to 12 l/min. figure 78. Cutaway of Airbi spray head (after Airbi, 1988)."}]},{"head":"Acridid Control Treatments","index":141,"paragraphs":[]},{"head":"Intervention tactics Intervention levels","index":142,"paragraphs":[{"index":1,"size":55,"text":"Intervention level depends upon the nature and the size of the target, the area to be treated and also local circumstances such as the quality and seasonal practicability of tracks, availability of aerial fleet, existence of field air strips, etc. Three levels could be distinguished with regards to the choice of relevant equipment (tab. XXVIII)."}]},{"head":"Portable equipment","index":143,"paragraphs":[{"index":1,"size":110,"text":"Hand-held ULV sprayers and motorised mist blowers could be ranked within this category. Hand-held ULV sprayers provide good quality spray but it is relatively irregular with motorised mist blowers. Therefore they need significant improvement so as to really be useful in acridid control. For technical as well as social reasons, the use of hand-held ULV sprayers are to be preferred, at farmer level, for the control of grasshoppers, especially during the early stages of cereal crops or other food crops. Considering preventive control of locusts, every survey team should have several hand-held ULV sprayers, besides vehicle-mounted equipment, so as to spray small areas as well as small size hopper bands."}]},{"head":"Vehicle-mounted equipment","index":144,"paragraphs":[{"index":1,"size":89,"text":"Until the 1980's, the exhaust nozzle sprayer was the only vehicle-mounted sprayer used in locust control. Now, several spray heads are adapted, with more or less success, from aerial equipment. Several attempts showed that conditions which prevail in locust control, especially in dry tropical zones, are ruthless to any equipment which is not well-designed. Many stores of anti-locust services are cluttered with machines which were barely used but are already broken down, because their design does not meet the requirements or because they were delivered without relevant spare parts."},{"index":2,"size":57,"text":"It should be stressed that the properties which ensure success are robustness, simplicity of use and handling. When vehicle-mounted ULV sprayers are well designed, they can be used at all levels of acridid control. They play a major role in preventive and curative control of locusts, because it is possible to perform either blanket or barrier treatments."}]},{"head":"Scouting for hopper bands","index":145,"paragraphs":[{"index":1,"size":116,"text":"Frequently, at the onset of outbreaks, infestations consist of many scattered hopper bands. The ability to locate them depends upon topography, vegetation type, vegetation thickness, hopper instars and density. Note that transiens hoppers of the Desert locust are yellow bright and, when they roost on bushes, they are visible from afar. It should be noted that when a hopper band is found in a place, it is almost certain that there are others in the surrounding zone and, if none is found it does not mean that there is not any. An upper wing aeroplane could be used to spot large hopper bands on short grass zones, but using helicopters in this operation is more successful."}]},{"head":"Scouting for adults","index":146,"paragraphs":[{"index":1,"size":58,"text":"Searching for adults is tenuous at best. Sometimes, when there are many adults on the area above which aerial survey is underway, it might be possible to spot them flying against light. However efficiency of swarm hunting with fixed wing aircraft is very poor. Helicopters are more efficient in pastoral zones where nomads may be of great help."}]},{"head":"In palliative locust control tracking and localisation of swarms","index":147,"paragraphs":[{"index":1,"size":140,"text":"This operation consists of tracking swarms until dusk when they land for night. This enables control teams to intervene immediately if they are operating in the surroundings or early in the morning of the following day. Considering their great mobility, helicopters are more suitable than aeroplanes but they should be long range models. To spot flying swarms, it is better to search for them when they fly swirling i.e. late in the morning and early in the afternoon. Aircraft should fly at low levels so that swarms could be seen on the horizon with the clear sky as the background. Under cloudy conditions the efficacy of this method is weak. Consideration should be given to the fact that a person cannot focus his attention for more than two hours. Four consecutive hours scouting might be required, but would be tiring."}]},{"head":"Settled swarms are difficult to locate on large grassland areas such as the Sahel.","index":148,"paragraphs":[{"index":1,"size":111,"text":"There is some chance to locate them if the most probable settling place is known. flagging Normally swarm tracking teams operate flagging for aircrafts which spray the following morning. The ideal tool is a helicopter equipped with GPS which is capable of giving the exact position as well as the exact size of the target. treatment During plague periods the main part of operations are made by means of aircrafts. At this level, except in mountainous areas, fixed wing aircrafts are the most suitable for spraying. Choice of aircraft type depends upon the size and the mobility of swarms. Ground support has a determining influence on the success of aerial operations."}]},{"head":"post treatment checks","index":149,"paragraphs":[{"index":1,"size":26,"text":"The helicopter is the ideal tool to execute this necessary operation. Post treatment checks are all the more necessary since equipment and chemicals involved are important."}]},{"head":"In grasshopper control","index":150,"paragraphs":[{"index":1,"size":139,"text":"Aircrafts of various categories were used for controlling grasshoppers, from heavy cargo aeroplanes (Douglas DC7) to microlights. Heavy cargo could be useful within integrated operations like French \"Écoforces\" in 1989. Due to high operating costs, they are less desirable for spraying. Microlight turned out to be too fragile to operate in Sahelian and Saharan conditions where the atmosphere might be subject to sudden changes. Actually, among fixed wing aircrafts, light aeroplanes are the most adapted to the requirements of grasshopper control. They have better efficiency regarding treated area (more than 2,000 ha/day) and lower cost-in-use. The great advantage of helicopters in grasshopper control lies in their versatility. They might be used for survey, spraying and post treatment checks. Running costs of this type of aircraft varies with the specifications of the model used, good range being a major factor."}]},{"head":"Types of acridid control treatments","index":151,"paragraphs":[]},{"head":"Blanket coverage","index":152,"paragraphs":[{"index":1,"size":41,"text":"It consists of treating a given infested area so as to achieve a uniform coverage. This is obtained by spraying according a track spacing shorter than the swath width, so that spray from each pass overlaps the deposit of the previous."}]},{"head":"Treating locust swarms","index":153,"paragraphs":[{"index":1,"size":44,"text":"Settled swarms should be treated early in the morning when cool temperature force them to remain on the ground. Trying to spray flying swarms is not efficient as well dangerous (obstruction of filters and loss of visibility due to locust impacts on the windscreen)."},{"index":2,"size":50,"text":"Chemicals used against swarms kill locusts mainly by direct contact which means that insects should be touched by droplets. Hence the spray quality is essential to ensure acceptable locust mortality. With vehicle-mounted and aircraft applications, track spacing varies with wind speed and the chemical used from 100 to 300 m."}]},{"head":"When knockdown insecticides are used, any re-infestation of a given zone, requires a new treatment even if it is covered with vegetation:","index":154,"paragraphs":[{"index":1,"size":8,"text":"• a few hours after application of pyrethroids,"},{"index":2,"size":14,"text":"• 24 hours after application of malathion, • 48 hours after application of chlorpyriphos."}]},{"head":"Treating hopper bands and grasshoppers","index":155,"paragraphs":[{"index":1,"size":37,"text":"It is preferable to use stomach action insecticides. The residual activity of the product and the vegetation thickness, determine the maximum track spacing which, in any case, should not exceed 400 m (fig. 79). It might be:"},{"index":2,"size":62,"text":"• 100 m, as maximum with contact action insecticides (pyrethroids, Metarhizium); • 200 m, as maximum with stomach and contact action insecticides (chlorpyriphos, imidacloprid); • 300 m, as maximum with stomach action insecticides (IGRs, fipronil). When vehicle-mounted sprayers are used, it is recommended to adopt a relevant approach with regards to the wind direction and the hoppers march (fig. 80 and  81)."}]},{"head":"Barrier treatments","index":156,"paragraphs":[]},{"head":"Background","index":157,"paragraphs":[{"index":1,"size":194,"text":"Barrier treatments were initiated in the former Soviet Union to combat Desert locust hopper bands in Central Asia (Kortkih & Starostin, 1945). Recommendations were then made to treat strips of 25-30 m and leave 45-50 m. Large scale tests were carried out in Indo-Pakistan desert during 1963 by the FAO Aerial Group of Operational Research, within a vast international program (FAO, 1968;Castel, 1982). Two objectives were pursued. The first was to treat rapidly Desert locust hopper bands, infesting very large areas, so that it will be possible to be able to intervene faster than the velocity of plague extension. The second was to decrease cots as much as possible. The principle was to use wide track spacing by rising progressively the emission height. Developing drift spraying technique was furthered by optimal use of lateral wind and the height efficacy and residual activity of dieldrin, an organo-chlorine insecticide. Ever since, barrier spraying offered to locust control, a determinant strategic factor. Gradually this technique was brought into general use, which allowed successful control of hopper bands in outbreak sources, before dispersal of initial swarms. Therefore barrier spraying became a valuable tool to locust plague prevention strategy."},{"index":2,"size":281,"text":"Since 1986, dieldrin was banned in locust control, because of its high toxicity, long lasting persistence and adverse ecological effects. The problems with dieldrin in locust control were topics of concern log before the withdrawal of the product. A project was carried out by the FAO (FAO-Swedish Fund-In-Trust) from 1971 to 1977 (FAO unpublished report) to find an effective insecticide as a substitute to dieldrin; however no product for barrier treatment was discovered. Since the banning of dieldrin, all insecticides used in locust control are mainly contact active with only one or a few days of residual activity. They must be applied directly on locust. For effective control, it was thus necessary to detect a spray every hopper band, with blanket coverage. Hence it was almost impossible to prevent widespread outbreaks (e.g. Desert locust upsurges in 1987 and 1993). In 1992 and 1993, \"barrier\" treatment trials were performed with diflubenzuron and triflumuron (benzoyl urea chemical family, also called IGR family) in Madagascar (Scherrer & Rakotonandrasan, 1993;Cooper et al., 1995;Tingle, 1996). In late 1993, fipronil, a compound of a new chemical family (phenyl-pyrazols) was proposed, by a company, as a substitute for dieldrin. The laboratory tests showed very good efficacy against locust, with good residual activity (Buttler & du Perez, 1994;Kriel, Buttler & du Perez, 1994;Megenasa & Muinamia, 1994). By the end of 1994, field tests with blanket coverage performed in Mauritania against Desert locust under Saharan conditions, established that the compound had excellent efficacy via both contact and ingestion, with effective residual activity (Rachadi et al., 1995). In October and November 1995, the Desert locust that occurred in Mauritania offered an opportunity to successfully perform a barrier treatment trial with fipronil."}]},{"head":"Definitions and principles","index":158,"paragraphs":[{"index":1,"size":205,"text":"The barrier technique adopted by locust control operators over several decades, is based upon drift spraying, whereby the wind speed, emission height and droplet size have a substantial influence on the actual swath width and shape. With the Acridid Control Treatments 103 barrier technique (fig. 82), track spacing precludes overlapping swaths. Droplet size and deposit rate decrease downwind and the deposit is not uniform. Sudden variations of wind direction or wind speed, variation of track spacing or the emission height, differential shading by hills or dunes are all application factors which may contribute to deposit variability and thus the variability of actual swath width. As such, it is possible to determine where a swath starts but it is relatively difficult to know exactly where it ends. Downwind displacement and the time a droplet is exposed to this effect, i.e. the emission height and droplet size. Castel and Balmat (1979) adopted an approach for applying dieldrin with a track spacing of 1,500 m and flying height of 50 m. Locust Handbook (Steedman, 1988) recommends 3,000 m as safe track spacing with both aerial and exhaust nozzle spraying. The method was first called \"vegetation baiting\", then \"poisoning the vegetation\" and finally the term \"barrier spraying\" was adopted."},{"index":2,"size":91,"text":"During all the 1960's and 1970's, when Desert locust control operators made recommendations concerning spray parameters, they gave neither a dose per hectare within the barrier nor the width of the strip serving as suitable barrier. Castel (1987) recommended spraying when the wind is rather strong so as to obtain the widest swath as possible. The parameters were 10 to 15 l/km of a dieldrin for the exhaust nozzle (depending on the vehicle speed) and 10 to 15 l/km for aircraft figure 82. Layout of barrier treatment procedure (after Steedman, 1988)."}]},{"head":"104","index":159,"paragraphs":[{"index":1,"size":187,"text":"Locust Control Handbook (depending on the flying speed), with an emission height of 20 to 50 m with a wind from 1 to 4 m/s. It did not matter whether the dieldrin was applied on relatively highly dosed strips over vegetation or generally over the whole area. Since the dieldrin accumulates in the locust bodies, the effect will be much the same if the insect acquires a lethal dose gradually as if it eats enough treated vegetation to kill it quickly. However Castel and Balmat (1987) recommended spraying swaths as wide as possible to avoid highly dosed strips in order to prevent endangering nomad livestock. Thus sprays were performed at a 50 m emission height and a wind speeds 5 to 7 m/s. Overall treatment did not, of course, rely on band movement and so did affect young nymphs, which died easily, as well as the older ones in marching bands. This was particularly relevant to hatching that may occur after spraying. The key of barrier treatment with the dieldrin is its persistence which permitted uneven coverage, wide track spacing and which avoids the need for respraying."},{"index":2,"size":117,"text":"By the end of the 1990's, when IGRs and the fipronil were introduced in locust control, barrier treatment became again possible. Unfortunately, skilled and experienced operators in barrier spraying had already left the field for many years and the concept of this technique was not well understood by temporary practitioners. Thus, a variant method which did not entirely correspond to the original technique, was adopted and also called \"barrier\". In trials conducted in Madagascar with IGRs (Scherrer & Rakotonandrasana, 1993;Cooper et al., 1995;Tingle, 1996), strip spraying was adopted as a barrier technique. In Wyoming, USA, an approach called RAAT (Reduced Agent Area Treatment) involved applying low rates of insecticides in intermittent swaths to control grasshoppers was tested."},{"index":3,"size":23,"text":"The objective was to achieve a more economically and environmentally sound pest management strategy in comparison to traditional blanket application at high rates."},{"index":4,"size":35,"text":"Since Desert locust plagues were causing tremendous damage, developers of barrier treatment were mainly motivated by, curbing and subsequently preventing plagues. Environmental benefits of barrier treatments were noticed and welcomed. They were not specifically sought."}]},{"head":"Performing barrier treatments with new compounds and equipment","index":160,"paragraphs":[{"index":1,"size":26,"text":"Barrier treatment as it was practised during the 1960's (Courshee & MacDonalds, 1963;FAO, 1968;Castel & Balmat, 1982;Steedman, 1988) according to parameters which varied for aerial applications:"},{"index":2,"size":8,"text":"• emission height: from 10 to 50 m,"},{"index":3,"size":10,"text":"• track: from 1,000 to 3,000 m (sometimes even more)"},{"index":4,"size":71,"text":"• wind speed: from 1 to 4 m/s. When barrier treatments were performed by means of exhaust nozzle sprayer, the track spacing might be as wide as 1,000 m (Castel, 1987) under a wind quite strong (5 to 7 m/s). Under lower wind forces track spacing were reduced but never below 500 m. In this case, they were resulting in coverage which was more irregular than coverage seen with barrier spraying."},{"index":5,"size":18,"text":"It should be noted that correct execution of barrier treatment is linked to chemical specifications and equipment performance."}]},{"head":"a. problems linked to the specifications of modern compounds","index":161,"paragraphs":[{"index":1,"size":118,"text":"Modern products which might be used as chemical agents for barrier treatments belong to two chemical families: phenyl-pyrazols (fipronil) and benzoyl-ureas or insect growth regulators (IGRs) (diflubenzuron, teflubenzuron, hexaflumuron). It should be noted that, to be eligible for barrier treatment, an insecticide should comply with four requirements: to be highly toxic for acridids, to have at least 3 weeks residual activity, to kill mainly by ingestion and induce an accumulation effect. Each of these requirements is necessary but not sufficient to ensure the success of the method. The first condition is necessary for ensuring a good efficacy at a low dose, the second and the third to ensure the killing of nymphs which are touched by spray droplets."}]},{"head":"insect growth regulators","index":162,"paragraphs":[{"index":1,"size":105,"text":"IGRs disrupt chitin synthesis, a basic cell constituent, which induce death of acridids while moulting. Accordingly IGRs are effective only against nymphs. As well as this specificity on young forms of insects, IGRs are effective only through stomach. They are reputed to have a residual activity of over four weeks but they do not seem to have a cumulative effect (Cooper et al., 1995). This might be a disadvantage since insects are likely to metabolize sub-lethal doses (Neuman & Guyer in Cooper et al.;Sherrer & Rakotonandrasana, 1993). However this phenomenon might be mitigated by the fact that nymphs are less mobile when they ingest IGRs."},{"index":2,"size":194,"text":"Another feature of IGRs is the variability of their toxicity against locust, i.e. the efficient dose varies with compounds (FAO, 1995). Among IGRs, diflubenzuron, triflumuron and teflubenzuron were more or less deeply tested for barrier applications, but so far, not all of them have been tested in operational conditions. However, even those which were successful are likely to allow barriers as wide as 1,000 m. The maximal track spacing for each compound should be determined by tests in operational conditions. fipronil is a compound of phenyl-pyrazols, a new insecticide family. Its effectiveness in barrier applications was proved by tests against hopper bands of Desert locust. A barrier treatment trial in operational conditions, showed that track spacing as wide as 2,000 m can be highly effective against Desert locust hopper bands (Rachadi & Foucart, 1996), without any modification to the spraying system of an aircraft usually used in locust control. The product had strong knock down effect together with a sustained stomach action. A residual activity over three weeks was revealed by tests performed in field conditions (Rachadi et al., 1995). from a strict technical point of view, fipronil fully complies with barrier treatment requirements."}]},{"head":"B. problems linked to spray equipment","index":163,"paragraphs":[{"index":1,"size":79,"text":"The volume of application (in l/ha), for barrier treatment, is markedly lower than that of blanket (0.075-0.150 l/ha compared to 0.5-1 l/ha). On the other hand, the volume per km to be applied does not sensibly vary and is usually between 10 and 15 litres per km. This is independent from the vehicle or aircraft speed and an adaptation of each type of equipment is required. Thus, the approach is not the same according to aerial or ground equipment."}]},{"head":"aerial equipment","index":164,"paragraphs":[{"index":1,"size":184,"text":"For blanket coverage, an aircraft flying at 130 km/h should have an output of 16.66 l/min, to apply 1 l/ha according to 100 m track spacing. For barrier, with the same flying speed, the output should be 32.5 l/min and 15 l per km for a track spacing as wide as 2,000 m. In the first case two spray heads can ensure a good droplet spectrum, while, in the second case, a minimum of four are required. In the first case, a 600 litre tank is emptied out within 36 min in the first case and 18 min in the second. This aspect should not be underestimated since a good droplet spectrum is a sine qua non condition for a successful barrier treatment. ground equipment Barrier treatments with ground equipment are submitted to the same requirements as for aerial. However, considering overdosing risks, it is preferable to use less concentrated formulations. Besides, emission height is lower and thus track spacing should not exceed 1,500 metres. At a speed of 10 km/h, the output might be 1.5-1.5 l/min for 10 to 15 litres per km."},{"index":2,"size":101,"text":"The exhaust nozzle sprayer (ENS) was widely used successfully, for barrier treatments, in preventive and curative control for almost three decades. Castel (1987) reported that droplet VMD was more than acceptable (50 to 120 microns) when mechanical and spray calibrations were correctly executed, even when the output was high (0.4-4.5 l/min but more frequently 1.5-3 l/min). Despite assertions of some people, disadvantages of ENS do not come from its failure to ensure correct droplet spectrum but from the difficulty to sustain mechanical and flow calibrations. The largest drawback of ENS was that its correct use requires very skilled and well-supervised people."},{"index":3,"size":9,"text":"Now the vehicle-mounted electrical sprayers supplant advantageously the ENS."},{"index":4,"size":33,"text":"They can provide outputs consistent with barrier application requirements together with good droplet spectrum. However, in view of their possible emission height and new pesticide specifications, track spacing should not exceed 1,000 metres."}]},{"head":"c. problems of real coverage in barrier spraying","index":165,"paragraphs":[{"index":1,"size":50,"text":"Droplet dispersal, i.e. the coverage, depends upon several factors which are globally determined by the spray parameters. Thus, droplet size, emission height and wind speed influence swath width. Even when basic parameters (output, displacement speed, track spacing droplet generation and emission height) are correctly calibrated, many uncontrollable factors may interfere:"},{"index":2,"size":25,"text":"• Wind speed which is never steady, in force and in direction. Wind force may vary from one to four times during the same treatment."},{"index":3,"size":17,"text":"• topography. Droplet deposit is affected by relief elements such as sharp contours, bare soil, slopes, etc."},{"index":4,"size":19,"text":"• plant cover. Trees, shrubs and bushes intercept droplets, leaving unsprayed, parts of grass layer, which exacerbates deposit variation."},{"index":5,"size":38,"text":"• thermal currents may be originated by surface heating due to insolation or advection or combination of the two. Air warmed by the ground beneath does not rise as continuous stream but rather than a series of bubbles."},{"index":6,"size":18,"text":"• ground treatments are affected by variations of forward speed, due to obstacles and vegetation along spray runs."}]},{"head":"d. problems related to the environment","index":166,"paragraphs":[{"index":1,"size":119,"text":"It should be noted that the actual swath is almost always larger than 1,000 m. Areas totally free from active ingredient are very rare. The objective of the inventors of this method is precisely to cover, with small amount of pesticide, the largest area as possible. Thereby, the area covered with a dose that can kill the insect at first contact is very small. Most often it varies from 15 to 30 % of the total area ( Van der Valk, 1988;Rachadi & Foucart, 1996). Dieldrin was thus applied according to sub-lethal coverage on the largest part of the area to be protected. Sublethal coverage was possible with dieldrin owing to its residual activity together with its cumulative effect."},{"index":2,"size":100,"text":"The concern for the preservation of non-target fauna and the specifications of modern compounds (IGRs and phenyl-pyrazols) argue for a new approach of barrier technique with the objective of leaving uncontaminated a part of the target area. The principle is to provide wide spacing between swaths and thereby offering the basis for relatively fewer non target impacts. It seems likely that the environmental harm of applying an insecticide with a 3-week residual to just one third to one half of the land will be less than blanketing the area with an insecticide having a 3-day residual (Lockwood et al., 2000)."}]},{"head":"Practice of treatments Basic calibrations","index":167,"paragraphs":[]},{"head":"Necessity of calibration","index":168,"paragraphs":[{"index":1,"size":26,"text":"Experienced locust control operators used to say that inefficacy of treatment is almost always due to inappropriate or lack of calibration and not to bad product."},{"index":2,"size":71,"text":"(fig. 83). Even if this possibility should not be discarded a priori, it should be admitted that a lack of information and unskilled staff is frequent. It is not rare to meet operators and technicians supplied with equipment without any document for maintenance or calibration instructions. Learning becomes then a question of imitation or by trial and error. Sometimes, when documents are available, they are so confusing that they are useless."},{"index":3,"size":101,"text":"In this book, the study of VLV and ULV spray equipment is favoured, because other spray techniques are seldom used in acridid control. Besides, mechanical matters were not thoroughly developed comparatively to calibrations and different aspects of maintenance routines which deserve priority. Before starting to spray, any equipment, aerial, ground or vehicle-mounted, should be submitted to basic calibrations. failure to do so will undoubted result in a drop of efficacy of the treatment. The spray operation supervisor has to ensure that all calibrations are correctly executed. three basic interdependent factors which determine the amount or volume of application per hectare are:"},{"index":4,"size":24,"text":"• flow rate or output. It is monitored by an orifice plate, an orifice nozzle, a combination of the two or a flow regulator."},{"index":5,"size":53,"text":"• forward speed. There are three scales of speed, from 3.5 km/h for knapsack sprayers, 5 to 15 km/h for vehicle-mounted sprayers to 90 to 250 km/h for aircrafts. Calibrations of forward speed will therefore be achieved respectively on 100 m, 500 m or 1 km (as a minimum) for aircrafts (fig. 84)."},{"index":6,"size":18,"text":"• distance between spray runs or track spacing. It depends on droplet size, emission release and wind speed."},{"index":7,"size":122,"text":"These three factors are closely interdependent, because if one is modified, one or both of the others should be modified in order to apply the same amount of formulation per hectare. Even if a sprayer is equipped with a sophisticated flow regulator, a manual flow check is always useful. Checking the output is essential every day before the first spray and before spraying another formulation even if it has the same content as that formerly used and also when another equipment is used even if it is the same as that used before. Besides, calibration and output checks should be performed with a liquid having a comparative viscosity to that of the formulation to be used or at least checked with it."},{"index":8,"size":53,"text":"Basically, manufacturers provide, with each model of equipment, a document (manual or handbook) which details the appropriate calibration and maintenance procedure. Unfortunately those documents are often missing when they are really needed. However with some experience and some resourcefulness, it is still possible to perform acceptable calibration, even when manufacturer's document is missing."},{"index":9,"size":42,"text":"Usually, in acridid control, the volume of application is determined beforehand, because it depends on the dose and the formulation available. To apply as accurately as possible the determined volume of application, it is required to adjust the three mentioned basic factors. "}]},{"head":"Tools for calibration","index":169,"paragraphs":[{"index":1,"size":31,"text":"To perform correctly the basic calibrations of these sprayer and other checking, it is necessary to provide a minimum of tools and various instruments of measures tools and utilities (fig. 85):"},{"index":2,"size":23,"text":"• a 10 l plastic bucket, preferably with pouring lip. Checking spray system of an aircraft requires a container for each spray head;"},{"index":3,"size":7,"text":"• a calibrated beaker (1 l volume);"},{"index":4,"size":6,"text":"• measuring tube of 250 ml;"},{"index":5,"size":7,"text":"• a small and a large funnel;"},{"index":6,"size":6,"text":"• a chronometer or a stop-watch;"},{"index":7,"size":8,"text":"• a thermometer to measure the air temperature;"},{"index":8,"size":8,"text":"• a toolkit adapted to the equipment used;"},{"index":9,"size":18,"text":"• various implements such as clean and dry rags, papers, small paint brush, signalling tapes, yellow flags, etc."},{"index":10,"size":3,"text":"• a compass;"},{"index":11,"size":10,"text":"• a measuring tape or better, an odometer (fig. 86)."},{"index":12,"size":3,"text":"figure 86. Odometer."}]},{"head":"Preliminary calculations","index":170,"paragraphs":[{"index":1,"size":14,"text":"Prior to practical task of calibrating, it is necessary to determine the target calibrations."},{"index":2,"size":11,"text":"The following examples of calculations explain how to derive these values."}]},{"head":"how to determine the forward speed","index":171,"paragraphs":[{"index":1,"size":49,"text":"The basic parameters: S = forward speed (km/h) T = track spacing (m) F = fl ow rate or output (l/min) V = volume of application (l/ha) When the output and the track spacing are determined, it is possible to calculate the forward speed by using the following formula:"},{"index":2,"size":51,"text":"1st example: if you are going to apply a formulation of fenitrothion at one litre per hectare (V) using a hand-held ULV sprayer with a fl ow rate of 0.6 l/min (F) and if the track spacing (T) is 12 m, what will be the walking speed (S) of the operator?"},{"index":3,"size":49,"text":"By using the formula the result is: S = 600 x 0.06 / 12 x 1 = 3 km/h 2nd example: to apply the same volume for application (V) using a vehicle-mounted sprayer, the output (F) of which is 1.4 l/min and the track spacing (T) is 70 m."},{"index":4,"size":73,"text":"In this case what will be the forward speed (S)? S = 600 x 1.4 / 70 x 1 = 3 km/h 3rd example: to spray a similar infestation with the same product at the same quantity (V), an aircraft sprays 25 l/min (F) according to 120 m track spacing (T). What should be the fl ying speed of the aircraft? S = 600 x 25 / 120 x 1 = 125 km/h"}]},{"head":"Recapitulation of the basics","index":172,"paragraphs":[{"index":1,"size":12,"text":"The basic parameters should be determined before starting any spray (tab. XXIX):"},{"index":2,"size":11,"text":"• The volume of application (v), expressed in litres per hectare."},{"index":3,"size":10,"text":"• The flow rate (output) (f) in litres per minutes."},{"index":4,"size":9,"text":"• The forward speed (S) in kilometres per hours."},{"index":5,"size":7,"text":"• The track spacing (t) in metres."},{"index":6,"size":9,"text":"• The emission height (h) of droplets in metres."},{"index":7,"size":9,"text":"• The lateral wind speed in metres per second."},{"index":8,"size":12,"text":"• The distance (d) over which droplets drifts before hitting the ground."},{"index":9,"size":6,"text":"• The sedimentation velocity of droplets. "}]},{"head":"Treatments with portable sprayers","index":173,"paragraphs":[{"index":1,"size":15,"text":"This category of equipment is composed of motorized knapsack mist blowers and hand-held ULV sprayer."},{"index":2,"size":98,"text":"Portable sprayers are normally adapted to the physical capabilities of a human adult. Their weight should not exceed 14 kg in full charge so that they may be normally carried by a person working normally under warm conditions. The monitoring system of the flow rate should be designed according to the speed of a person walking normally unhurriedly (one metre per second). In light of these two elements, the problem is different when spraying with a hand-held ULV sprayer compared to motorized knapsack mist blower, since the weight of the latter is an additional factor of spray unevenness."}]},{"head":"Basic calibrations","index":174,"paragraphs":[]},{"head":"Calibration and checking flow rate","index":175,"paragraphs":[{"index":1,"size":34,"text":"Although the basic principle of the flow rate calibration is the same, the operating method is different for each model of equipment, therefore an appropriate method will be developed for each type of equipment. "}]},{"head":"How to determine the fl ow rate (F)","index":176,"paragraphs":[{"index":1,"size":23,"text":"When the volume of application (V), the forward speed (S) and the track spacing (T) are known, the following formula can be applied:"},{"index":2,"size":30,"text":"1st example: a formulation with Malathion is to be applied at 5 l/ha (V) with a knapsack mist blower. Considering that the walking speed (S) of the operator is 3. "}]},{"head":"Calibration of forward speed","index":177,"paragraphs":[{"index":1,"size":136,"text":"Steadiness of forward speed depends, among other things, on the ability of each operator to monitor his walking. It is evident that the walking speed will be difficult to control as the sprayer is heavy, which is the case with knapsack motorized mist blowers. Portable sprayers are designed for an adult i.e. walking slowly at more or less 1 metre per second. Every operator should adjust his steps in accordance with this walking speed. Two scenarios are possible: either the operator adjusts his walking steps to a determined speed and maintains this pace or calibrates to his normal speed keeping in mind that he should not modify it afterward. Then he adjusts the output accordingly. In all cases, measurements and calibrations should be performed by an operator while carrying a sprayer with the tank half full."}]},{"head":"Determining track spacing","index":178,"paragraphs":[{"index":1,"size":49,"text":"With knapsack mist blowers, track spacing depends on the range of the air stream i.e. the power of the machine. When using controlled drift spraying with these types of equipment, track spacing depends on the emission height and wind the speed during treatment (see § ULV formulations p. 34)."},{"index":2,"size":67,"text":"The minimum emission height for drift spraying is one metre above the vegetation. The maximum emission height depends upon the specifications of the equipment. It is 2.5 m when using hand-held ULV sprayers (fig. 87) and 3 to 4 m with mist blowers equipped with an appropriate droplet generator. table XXXi. Drift of droplets and the maximum track spacing to be adopted with portable sprayers (Rachadi, 1989). "}]},{"head":"Motorised knapsack mist blowers Calibration and checking flow rate","index":179,"paragraphs":[{"index":1,"size":23,"text":"Two scenarios may be encountered depending whether or not it is possible to disconnect the liquid circuit and collect formulation in separate receptacle."},{"index":2,"size":8,"text":"first case: the liquid circuit cannot be disconnected."},{"index":3,"size":15,"text":"• Set the sprayer on a stable area so that the filling orifice is horizontal."},{"index":4,"size":20,"text":"• Fill the tank with the formulation up to filling orifice neck or to the bottom of the filter gauze."},{"index":5,"size":14,"text":"• Set the flow regulator to the appropriate position or place the required nozzle."},{"index":6,"size":14,"text":"• Start the engine and accelerate until the blower reaches its nominal rotational speed."},{"index":7,"size":15,"text":"• Open the control valve, let the formulation flow until the whole circuit is full."},{"index":8,"size":17,"text":"• Close the control valve, stop the engine, refill the formulation tank up to the orifice neck."},{"index":9,"size":14,"text":"• Re-start the engine and accelerate until it reach its normal speed for spray."},{"index":10,"size":31,"text":"• Open the control valve and, at the same time, start the chronometer (or a stop watch). Let it spray for one minute. Close the control valve at sixty seconds time."},{"index":11,"size":4,"text":"• Stop the engine."},{"index":12,"size":8,"text":"• Set the sprayer at the initial position."},{"index":13,"size":11,"text":"• Refill the tank. The added quantity should be carefully measured."},{"index":14,"size":20,"text":"• If the added quantity is significantly different from that expected, modify accordingly the flow regulator and repeat the operation."},{"index":15,"size":32,"text":"• When the result is close to that expected (more or less 5%), make a few more tests and adopt their average. Second case: it is possible to disconnect the liquid circuit."},{"index":16,"size":11,"text":"• Put a few litres of the formulation into the tank."},{"index":17,"size":22,"text":"• Disconnect the formulation hose from the airflow nozzle and make sure it can pour into a bucket or a measuring cylinder."},{"index":18,"size":14,"text":"• Start the engine and accelerate until the blower turns at its normal speed."},{"index":19,"size":14,"text":"• Set the flow regulator at the position corresponding to the required flow rate."},{"index":20,"size":20,"text":"• Open the control valve and let the liquid flow so that the circuit is bled and full of liquid."},{"index":21,"size":17,"text":"• Close the control valve, empty the cylinder into the formulation tank. Do not stop the engine."},{"index":22,"size":13,"text":"• Again put the formulation hose into the measuring cylinder or the bucket."},{"index":23,"size":13,"text":"• Open the control valve and at the same time start the chronometer."},{"index":24,"size":16,"text":"• Let the formulation flow for one minute and, at sixty second time, close the control."},{"index":25,"size":5,"text":"• Measure the liquid collected."},{"index":26,"size":19,"text":"• If this quantity is significantly different from that expected, adjust the flow regulator accordingly and repeat the operation."},{"index":27,"size":30,"text":"• When the quantity of liquid collected is close to that expected (more or less 5%), repeat the operation 3 times to be sure that the flow rate is steady. "}]},{"head":"Spraying","index":180,"paragraphs":[{"index":1,"size":42,"text":"When using ULV technique to spray 1 l/ha it is useless to fill up a 10 l tank, since an operator cannot spray 10 ha nonstop. Spraying should not start unless all the basic parameters have been determined and the calibrations performed."},{"index":2,"size":9,"text":"• Delimit by flags the field to be treated."},{"index":3,"size":8,"text":"• Begin the spray at the side downwind."},{"index":4,"size":39,"text":"• In optimal conditions the wind direction is perpendicular to the spray runs (fig. 22). To have a constant watch of wind direction, it is advisable to provide a permanent source of smoke or a flag of light plastic."},{"index":5,"size":42,"text":"• Walk forward, at regular speed, according to the calibrated speed (fig. 89). Care should be taken to avoid the natural tendency to spray rocking from side to side. It would be better if the spray nozzle is fixed upward (fig. 36)."},{"index":6,"size":16,"text":"• Never spray during stops. Close the control valve even if the engine is not stopped."}]},{"head":"Hand-held ULV sprayers","index":181,"paragraphs":[]},{"head":"Flow rate calibration","index":182,"paragraphs":[{"index":1,"size":93,"text":"The output depends on the flow restrictor orifice and the viscosity of the formulation. Temperature variation also influences the output, since high temperature may quicken the flow and vice versa. Therefore, the output should be checked every time if one of the parameters has changed (new formulation, volume of application, walking speed or track spacing) or when there is a dramatic change in temperature. Anyhow, the output should be checked under working conditions, at least once before starting to spray at each site. For flow rate calibration, the following procedure may be applied:"},{"index":2,"size":7,"text":"• Make sure the sprayer works correctly."},{"index":3,"size":11,"text":"• Choose and fit the appropriate restrictor nozzle (or feed nozzle)."}]},{"head":"Wind","index":183,"paragraphs":[]},{"head":"Acridid Control Treatments","index":184,"paragraphs":[]},{"head":"119","index":185,"paragraphs":[{"index":1,"size":16,"text":"• Fill the bottle with the formulation to about half a litre, by using a funnel."},{"index":2,"size":12,"text":"• Place a measuring cylinder or a container on a stable surface."},{"index":3,"size":10,"text":"• Remove the atomiser disc and turn over the sprayer."},{"index":4,"size":44,"text":"• Wait until the flow is steady and then let the liquid flow into an empty container (or measuring cylinder) for one minute. It is very important to trigger the stop watch at the moment the liquid begins to flow into the empty container."},{"index":5,"size":32,"text":"• Measure the liquid dispensed. If the quantity collected in one minute is significantly (more or less than 5 %) different from that expected, change the nozzle and repeat the preceding procedure."},{"index":6,"size":23,"text":"• If the output is close to that expected (more or less 5%), repeat the operation two more times and adopt the average."}]},{"head":"Choosing emission height","index":186,"paragraphs":[{"index":1,"size":40,"text":"The minimal emission height above the vegetation is one metre. If the weather is calm or when the vegetation is thick, the sprayer may be held so that the spray head is about 2.5 m above the vegetation (fig. 87)."}]},{"head":"Choosing track spacing","index":187,"paragraphs":[{"index":1,"size":53,"text":"The most appropriate track spacing depends upon the behaviour of the target (see § Target and active ingredient, p. 7) and the mode of action of the active ingredient. The actual track spacing will be imposed by versatile factors which are vegetal cover shape, formulation, wind speed, possible emission height and droplet size."},{"index":2,"size":32,"text":"The ideal wind speed varies from 1 to 3.5 m/s. Below 1 m/s, drift is not sufficient and, above, droplets may fly beyond the target zone and the coverage might be sparse."},{"index":3,"size":63,"text":"As a matter of fact, with these sprayers, almost all the parameters are imposed and only track spacing leaves some flexibility to the operator. The recommendations given in table XXXI take into account an overlapping of three swaths (fig. 90), under blanket treatment conditions. When spraying pesticide with long residual activity, track spacing might be twice as wide as indicated in the table. "}]},{"head":"Spraying","index":188,"paragraphs":[{"index":1,"size":27,"text":"Globally, the tactic is the same as described in § \"Choosing emission height\". Basic calibration being fulfilled, it is however necessary to carefully execute the following tasks:"},{"index":2,"size":14,"text":"• Check that the correct number of batteries is being used for ULV application."},{"index":3,"size":6,"text":"• Check direction and wind speed."},{"index":4,"size":17,"text":"• Fill the bottle and seal it carefully. Hold the sprayer in the stand-by position (fig. 91)."},{"index":5,"size":15,"text":"• Before starting, remove the disc cover and put it away in a secure place."},{"index":6,"size":40,"text":"• Stand at the starting point to begin the first spray line. This point is situated at the top of downwind edge of the land to be treated. Start inside the land, at a distance equivalent to a track spacing."},{"index":7,"size":18,"text":"• Hold the sprayer head downwind so that the wind takes droplets away from the operator when spraying."},{"index":8,"size":23,"text":"• Adjust the spray head to the correct emission height and set it so that the flow nozzle is close to vertical position."},{"index":9,"size":34,"text":"• Switch on the sprayer and check if spray disc is spinning correctly (with some experience an operator can identify the correct sound). The rotational speed can also be checked by using a tachometer."},{"index":10,"size":26,"text":"• Wait until the motor reaches its maximal rotational speed. Never touch the disc when spinning or hold the spray head too close to the operator."},{"index":11,"size":73,"text":"• Turn the sprayer so that the bottle upside down (fig. 91) and start walking immediately at the rhythm acquired during walking speed calibration. The flow nozzle should be maintained at vertical position. Hold the sprayer slightly to the rear so that the operator walks away from the spray mist. care should be taken to restrain the tendency to lower the sprayer downwards or to slow down when meeting concentrated spots of acridids."},{"index":12,"size":23,"text":"• Walk straight towards the flag which should be placed in a position where it can be seen by the operator while spraying."},{"index":13,"size":29,"text":"• At the end of a spray pass, turn over the sprayer so that the bottle is underneath of the spray head (fig. 91), then switch off the sprayer."},{"index":14,"size":22,"text":"• Move upwind to the starting point of the next spray pass. count the number of steps corresponding to the track spacing."},{"index":15,"size":16,"text":"• Walk until the end of the spray pass and repeat the operation as described above."},{"index":16,"size":35,"text":"• When several operators spray the same field, every one should be away from the spray mist of the other, and never walk through any part of the field that has been sprayed (fig. 92)."}]},{"head":"Maintenance","index":189,"paragraphs":[{"index":1,"size":49,"text":"Good and regular maintenance is a condition to ensure a good longevity of equipment and spray accuracy. A tool kit and some instruments are required to perform the maintenance operations. maintenance tool kit (after Ciba-Geigy, 1984) • two screwdrivers (medium and small size), • a Philips screwdriver (medium size),"},{"index":2,"size":86,"text":"• a metallic brush or abrasive cloth, • a small paintbrush, • a pair of tweezers, • a pair of wire stripping pliers, • a pair of flat nose pliers, • a vibrating wire tachymeter (\"Vibratak\") • a voltmeter or a torch or a torch lightbulb and small wire (fig. 93).  • frequently check if the flow is correct. Regularly verify that the nozzle orifice is not obstructed. When required remove impurities by means of a fine stem. never blow into the nozzle with the mouth."},{"index":3,"size":39,"text":"• periodically check the rotational speed of the spray disc. It should spin at its nominal speed. When possible use a pocket tachometer such as \"Vibratak\". In case of malfunction, search for the cause and the remedy (tab. XXXII)."},{"index":4,"size":60,"text":"• As soon as a rotational slow down is noticed, battery condition should be checked (fig. 93). A set of batteries can provide enough energy for 3 to 4 hours of intermittent use. maintenance routine for hand-held ULv sprayers • On the whole, manufacturer's recommendations should be followed, particularly those concerning maintenance, as well as instructions for troubleshooting (tab. XXXII)."},{"index":5,"size":16,"text":"• Before starting to spray, it is recommended that all the checks mentioned above be performed."},{"index":6,"size":39,"text":"• Make sure the spray liquid never contacts the motor axis. To prevent this from occurring, always switch on the motor before turning down the spray head and always turn up the spray head before switching off the motor."},{"index":7,"size":43,"text":"• Follow the manufacturer's procedure for placing or removing the battery set. When the latter has run down, it is also essential to change the whole set composed by identical elements. Never mix old and new batteries, this could harm the sprayer motor."},{"index":8,"size":23,"text":"• At every end of day dispose of the remaining formulation in the original container and flush the sprayer with diesel or kerosene."},{"index":9,"size":20,"text":"• Meticulously clean the bottle, the disc, the motor shaft by means of a dry cloth or clean soft paper."},{"index":10,"size":21,"text":"• Before storage for a long period, the spray head should be disassembled and cleaned and re-assembled according to manufacturer's instructions."}]},{"head":"123","index":190,"paragraphs":[]},{"head":"Treatments with vehicle-mounted sprayers","index":191,"paragraphs":[{"index":1,"size":34,"text":"Vehicles intended for carrying anti-acridid sprayers should be adapted to their purpose. First, the engine should be diesel as gasoline vehicles are not acceptable because the gear box does not allow suitable speed range. "}]},{"head":"Symptom possible cause remedy","index":192,"paragraphs":[]},{"head":"Basic calibrations","index":193,"paragraphs":[]},{"head":"Flow rate calibration","index":194,"paragraphs":[{"index":1,"size":39,"text":"Although every model is provided, by the manufacturer, with a specific calibration procedure, it is possible to emphasise some general principles which enable operators to perform correct calibration if the calibration document is missing. Two cases may be encountered."},{"index":2,"size":14,"text":"first case: the liquid can be collected at the spray head (Dyna-Jet and Ulvamast)."},{"index":3,"size":5,"text":"The procedure is as follows:"},{"index":4,"size":12,"text":"• Place the vehicle on a stable flat area. Put the handbrake."},{"index":5,"size":8,"text":"• Make sure the drain valve is closed."},{"index":6,"size":12,"text":"• Pour a few litres of the liquid into the formulation tank."},{"index":7,"size":9,"text":"• Place a clean bucket underneath the spray head."},{"index":8,"size":12,"text":"• Place the orifice restrictor plate and/or adjust the flow control valve."},{"index":9,"size":18,"text":"• If the power is provided by the vehicle, start the vehicle engine; otherwise start the sprayer engine."},{"index":10,"size":34,"text":"• For spinning spray heads, start only the formulation pump so as to allow the liquid to turn in a closed circuit; then adjust the pressure according to manufacturers' indications related to the model."},{"index":11,"size":28,"text":"• Open the flow control (or switch on the pump) and let the liquid to flow a few seconds into the bucket so that the circuit is bled."},{"index":12,"size":18,"text":"• Close the flow valve (switch off the pump), then pour back the liquid into the formulation tank."},{"index":13,"size":58,"text":"• Again put the bucket underneath the spray head and open the flow valve (switch on the pump, do not run the spray head!). The moment the liquid begins to flow from the spray head trigger the stop watch. Let the liquid flow for sixty seconds; close the flow valve (switch off the pump) at the right moment."},{"index":14,"size":5,"text":"• Measure the liquid collected."},{"index":15,"size":12,"text":"• Compare to the expected output and adjust the flow regulator accordingly."},{"index":16,"size":33,"text":"• Repeat the operation until the output is close to that expected. The difference should be less than 5%. When the output is acceptable, repeat the operation three times to confirm the result."},{"index":17,"size":19,"text":"Second case: the liquid cannot be collected at the spray head (autonomous mist blowers). The procedure is as follows:"},{"index":18,"size":41,"text":"• Stop the vehicle on a stable and flat area where pollution risks are minimal (especially in case of accidental spill of formulation). The sprayer head should be directed downwind so that the spray mist would not contaminate the working place."},{"index":19,"size":8,"text":"• Check that the drain valve is closed."},{"index":20,"size":6,"text":"�� Fill up the formulation tank."},{"index":21,"size":5,"text":"• Start the sprayer engine."},{"index":22,"size":27,"text":"• Start the formulation pump and let the liquid to flow in an internal circuit. Adjust the pressure according to the manufacturer's indications related to the model."},{"index":23,"size":23,"text":"• Open the flow valve and spray a few seconds to allow the liquid to fill the circuit and expel air from it."},{"index":24,"size":5,"text":"• Close the flow valve."},{"index":25,"size":16,"text":"• Refill the formulation tank. Notice the exact level of the liquid in the filling orifice."},{"index":26,"size":27,"text":"• Open the flow valve and at the same time trigger the stopwatch. Let the liquid flow sixty seconds. Close the flow valve and stop the engine."},{"index":27,"size":12,"text":"• Refill the formulation tank with a measured quantity of the formulation."},{"index":28,"size":14,"text":"• Compare the added quantity with that expected and correct the flow regulator accordingly."},{"index":29,"size":32,"text":"• Repeat the operation until the flow is close to that expected. When the output is acceptable, repeat the operation, to confirm the result and adopt the average as the flow rate."}]},{"head":"Forward speed calibration","index":195,"paragraphs":[{"index":1,"size":64,"text":"The great diversity of all terrain vehicles and their several ranges of forward speed (tab. XXXIII) impose forward calibration of each vehicle. But this is rather difficult since most of the vehicles are not equipped with an engine tachymeter nor with a hand accelerator. A calibration procedure is detailed hereinafter but results do not have acceptable accuracy unless vehicles are equipped with mentioned devices."},{"index":2,"size":18,"text":"It should be mentioned that speedometers of vehicles (km/h) are not accurate enough below 20 kilometres per hour."},{"index":3,"size":15,"text":"table XXXiii. Average forward speed (km/h) of different vehicles according to their gear shifting (Rachadi,1989)."},{"index":4,"size":60,"text":"Two people are necessary to perform forward speed calibration: a driver and the spraying supervisor. Measurement instruments should be provided (fig. 85 and 86) i.e. a stop watch, an odometer or measure tape. During the operations the supervisor is seated in the cab on the passenger seat) holding the stop watch (fig. 84). The calibration procedure is conducted as follows:"},{"index":5,"size":30,"text":"• choose a flat area where a 500 m distance can be easily delimited. A normal trail in the bush is suitable. However, rough path or tracks should be avoided."},{"index":6,"size":38,"text":"• delimit a straight line of 500 m by fixing a staff in each limit. • Start running at about 50 m before the first staff so as to run at regular speed when entering the delimited zone."},{"index":7,"size":74,"text":"• adjust the acceleration so that the engine runs at its normal speed; do not race it or run at too low speed. If the vehicle is equipped with a tachymeter, it is possible to spot the adequate engine speed. Once the correct engine speed is adopted, it should be kept during the whole tests and spraying operations. This is easy if the vehicle is equipped with a hand accelerator but rather difficult otherwise."},{"index":8,"size":16,"text":"The problem can however be mitigated by fitting a wedge under the pedal of the accelerator."},{"index":9,"size":9,"text":"• Start running and shift into the chosen gear."},{"index":10,"size":26,"text":"• adjust the engine speed up to the chosen level. The vehicle should run steadily when it passes before the first shaft without varying the acceleration."},{"index":11,"size":18,"text":"• the passenger triggers the stopwatch at the very moment he passes in front of the first staff."},{"index":12,"size":21,"text":"• the vehicle cross the 500 m without varying its forward speed. Do not vary the gear nor the engine speed."},{"index":13,"size":17,"text":"• do not slow down when approaching the second staff but pass it keeping the same speed."},{"index":14,"size":17,"text":"• the passenger stops the stopwatch at the very moment he passes in front of the shaft."},{"index":15,"size":15,"text":"• Stop the vehicle, read the time and compare with the reference data (tab. XXXIV)."},{"index":16,"size":12,"text":"• repeat the operation three times and adopt the average (fig. 94)."},{"index":17,"size":6,"text":"• calculate the corresponding speed (km/h)."},{"index":18,"size":23,"text":"it clearly appears that only double gear vehicles (with reduction) should be used in acridid spraying; others are too fast to be suitable. "}]},{"head":"Determining track spacing","index":196,"paragraphs":[{"index":1,"size":79,"text":"The actual track spacing will always be the result of a compromise between possibilities and constraints. The possibilities are determined by natural factors (wind speed thermal conditions) and technical factors (emission height and droplet spectrum, etc.). These constraints impose certain limits on the potential possibilities. The pesticide mode of action and the volume of application are very important, but the nature and thickness of the plant cover and gear combinations of the vehicle play a bit role as well."},{"index":2,"size":62,"text":"The emission height generally ranges from 2 to 10 metres. It should be determined at the beginning of each day and when of the key factor is changed i.e. permutation of the vehicle or change in the wind speed. If the wind subsides, it is always preferable, whenever possible, to rise the emission height rather than shortening the track spacing (fig. 95)."},{"index":3,"size":42,"text":"For the sake of optimization and within the limits of sprayer specifications, in most cases, track spacing varies from 100 to 400 m for blanket coverage, 400 to 1,000 m for irregular coverage and 1,000 to 1,500 m for barrier (tab. XXXVI). "}]},{"head":"Treatment procedure","index":197,"paragraphs":[]},{"head":"General principles","index":198,"paragraphs":[{"index":1,"size":83,"text":"Before starting to spray, the target should be clearly defined (size, mobility, harmfulness, vulnerability) and the basic parameters determined. Acceleration should not be modified during spraying for all the sprayer mentioned above, except for the L15 of Curtis Dyna-Fog, thanks to its radar system. The position of the gear should not be modified unless one or more other basic parameters are modified (output or track spacing). Write down the distance covered during spray runs so that the overall treated area could be calculated."},{"index":2,"size":79,"text":"The most suitable direction of spray runs is perpendicular to wind direction. But actually wind direction often varies after spray run orientation has been chosen. Field topography may also impose another angle. However the final result will remain satisfactory as long as the angle is not less than 25 degrees. While being relatively fixed with regards to the wind direction, track spacing shape may vary with marching hopper bands.  (Rachadi, 1989). Volume (litres) of technical Malathion applied per hectare."},{"index":3,"size":26,"text":"table XXXiX. Abacus for the use of Toyota Land Cruiser diesel equipped with exhaust nozzle sprayer (Rachadi, 1989). Volume (litres) of technical Malathion applied per hectare."}]},{"head":"Treatments with aerial equipment","index":199,"paragraphs":[]},{"head":"Flow rate calibration","index":200,"paragraphs":[{"index":1,"size":140,"text":"Basically, aerial application should not be performed without scrupulous flow rate calibration. Considering the low volumes involved and the highly concentrated formulations used in acridid control, calibration mistakes may have negative effects on the efficacy and the environment. The consequences may also be costly to the affected countries and to the international community of donors. For the same reason, calibrations of ULV formulations should be performed with a neutral liquid having the same viscosity as the formulation. Aircrafts equipped with electric or hydraulic pumps can be adjusted on the ground. In this case, calibration may be made directly by using the formulation itself provided the liquid is collected. When the aircraft is equipped with a propeller pump, calibration is made in flight.  • Make the necessary adjustments by varying the pressure, the distance or the orifice plates of the nozzles."},{"index":2,"size":32,"text":"• Put into the tank the exact quantity of formulation for a one or two minute spray, then execute a final check spray flight over the target zone while recording the time."},{"index":3,"size":12,"text":"• After landing, if required, make a last adjustment of the pressure."}]},{"head":"Ground calibration","index":201,"paragraphs":[{"index":1,"size":19,"text":"• Pour 10 to 15 litres of the formulation (or a liquid having the same viscosity) into the tank."},{"index":2,"size":8,"text":"• Set the VRU at the required output."},{"index":3,"size":17,"text":"• Start the aircraft engine and the spray pump so that the spraying system is under pressure."},{"index":4,"size":29,"text":"• Place a clean bucket underneath each spray head, then open the flow valve and let the liquid to pour out until the air is flushed from the system."},{"index":5,"size":22,"text":"• Close the flow valve. Pour back the collected liquid into the tank and place again the buckets underneath the spray heads."},{"index":6,"size":16,"text":"• Collect the spray liquid over one or two minutes and then close the flow valve."},{"index":7,"size":23,"text":"• Measure the liquid collected from each spray head and compare with the expected output. Adjust the pressure accordingly or choose another orifice."},{"index":8,"size":26,"text":"• When the correct orifice and right pressure are found, a final fly test is useful and might be followed by a last adjustment of pressure."}]},{"head":"Determining track spacing","index":202,"paragraphs":[{"index":1,"size":45,"text":"For the sake of cost optimisation, the widest track spacing will be preferred as long a correct spray is possible. Actually, it is a matter of finding a compromise between the requirements of acridid control (quick intervention together with maximal efficacy) and the following constraints:"},{"index":2,"size":14,"text":"• plant cover: With high and thick vegetation tracks spacing should not be wide."},{"index":3,"size":33,"text":"• type of formulation: Water-based formulations does not suit ULV technique. Large droplets are required so that they may rapidly impact the vegetation. They cannot bear important drift because of high evaporation risk."},{"index":4,"size":20,"text":"• the insecticide mode of action: When using short knockdown short persistence insecticides, track spacing must be narrower and vice-versa."},{"index":5,"size":13,"text":"• the wind speed/emission height combination must be taken into account (tab. XL)."},{"index":6,"size":48,"text":"Depending on the insecticide and the type of biological target, track spacing between 100 and 400 metres are adopted for blanket coverage, 400 to 1,000 for irregular coverage and 1,000 to 2,000 for barrier. In most cases of blanket coverage, track spacing varies from 100 to 150 metres."},{"index":7,"size":17,"text":"Essentially, the basic principle is to make sure that the swaths overlap for blanket application (fig. 96).  "}]},{"head":"Recapitulation of application parameters volume of application per hectare","index":203,"paragraphs":[{"index":1,"size":12,"text":"It is pre-determined by the dose of application and the formulation content. "}]},{"head":"Spraying","index":204,"paragraphs":[{"index":1,"size":247,"text":"First, the pilot flies over the site and lines up towards two flags at each side of the target zone. Then he descends to the spaying height for the first pass and starts the spray just above the first flag. He flies a series of passes, gradually moving upwind across the target zone (fig. 97). At the end of each pass the pilot has to complete a procedure turn. Initially, as he approaches the end of a pass, he increases the power, shut off the spray, pull up sharply to above 15 m, turns away about 45 o and then brings the aircraft to approach the next swath. The power required depends on the load and height of obstacles but adequate speed and power are essential to guard against stalls or incipient spins. Sometimes it is possible to fly a \"race track\" pattern (fig. 98) which allows a wider turn but necessitates additional flag men, which is not always available in remote and desert areas. The race track pattern can give a more even spray coverage, as the aircraft is flying successive passes in the same direction. When obstructions are close to the edge of the field, the pilot will normally fly one or two passes along the edge and along each headland to \"finish off\" after completing the main part of the field (Matthews, 1979). solely to enhance military defence capabilities, GPS have expanded to provide highly accurate position and timing information for many civilian application."},{"index":2,"size":102,"text":"The basic GPS is defined as the constellation of 24 satellites in six orbital circle paths which circle the earth twice each day at an inclination angle of approximately 55 degrees to the equator. The satellites are travelling at a speed of about 12,000 km/h, which allows them to circle the earth once every 12 hours. They are powered by solar energy and are built of last about 10 years. If the solar energy fails (eclipse, for example), they have backup batteries on board to keep them running. They also have small rocket booster to keep them flying in the correct path."},{"index":3,"size":324,"text":"this constellation of satellites continuously transmits coded positional and timing information at high frequencies. One of the frequencies is devoted to the civilian receivers. The signals travel a \"line of sight\", meaning it will pass through clouds, glass and plastic but not go through most solid object such as buildings and mountains. GPS receivers with antennas located in a position to clearly view the satellites, pick up these signals and use the coded information to calculate a position in earth coordinate system. When introduced in 1993 the GPS standards available to civilian users, incorporated a deliberate degradation of the system's accuracy using a technique known as \"Selective Availability\". Horizontal positional accuracies of 100 m became available. On 1st May 2000, the US Department of Defense discontinued the use of selective availability, rending possible a much higher degree of accuracy. Thus the new horizontal accuracy standards are based on signal space errors and state a global average error of less than 13 metres. Differential GPS (DGPS) removes this induced error as well as errors caused by ionospherical interference. It also removes multipath errors caused by the satellite signals that bounce off terrain features before reaching the GPS receiver. DGPS positioning data can be accurate to within a metre or less. GPS guidance technology systems become necessary in acridid control. They allow the control team to delineate spray plots by integrating, if possible, Geographical Information System (GIS) positional information into the aircraft system. They give the pilot the ability to navigate directly from the airstrip to the plot and back. They give the pilot guidance in aligning each spray path across the plot and provide a record of the area that was sprayed. These records can be viewed on the GPS system screen in the cockpit for immediate correction or can be downloaded to a computer. The downloaded spray records can be achieved and later imported into a GIS system for analysis with spray deposition models."}]},{"head":"Receiver technology","index":205,"paragraphs":[{"index":1,"size":169,"text":"Receivers are parallel multi-channel design. They have between 5 and 12 receiver circuits, each devoted to one particular satellite signal. So, strong locks can be maintained on all the satellites all the time. Parallel channel receivers are quick to lock onto satellites when first turned on and they are unequalled in their ability to receive the satellite signal even in difficult conditions. Receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. That make the technology very accessible and GPS navigation is becoming more common. GPS is the only system of the kind available for civilian uses but not for long. Within a few years, galileo, an European system will complete and compete with the American GPS system to form the gnSS: global navigation Satellite System. With Galileo, the availability of two or more constellations, more than doubling the total number of available satellites in the sky will enhance the quality of the services, thus increasing the number of potential users and applications."},{"index":2,"size":51,"text":"The existence of two independent systems is a benefit to all users since they will be able to use the same receiver to pick up both GPS and Galileo systems. The GNSS system (Galileo + GPS) will allow development of algorithms which can lead to centimetre accuracy most of the time."}]},{"head":"Choosing receivers","index":206,"paragraphs":[{"index":1,"size":64,"text":"The price is of course an important factor. However down-market receivers should be avoided, as they may have important limitations. Sometimes the necessary accessories are very expensive. The possibility of connection with a computer and the availability of out antenna should be carefully considered. Do not neglect the display size, the simplicity of use and the possibility of being connected to the vehicle batteries."}]},{"head":"Benefits of GPS technology","index":207,"paragraphs":[{"index":1,"size":44,"text":"GPS technology has made a great improvement in acridid control applications. Therefore this equipment should required whenever possible in all aerial or ground application. The benefits to be drawn from GPS technology includes precise delimitation of target zones and accurate guidance of spray tracks."}]},{"head":"Delimitation of target zones","index":208,"paragraphs":[{"index":1,"size":246,"text":"GPS can offer significant time saving by reducing set up time at survey site. It also provides accuracy down to less than 10 metres which is sufficient for a good delimitation of target areas. This is particularly useful when an infested area contains excluded zones such as villages or ponds. This possibility is a great advantage since it implies reducing the quantity of pesticide use while preserving the environment. A typical GPS installation in an aerial application aircraft consists of a moving map display, key pad mounted on the cockpit instrument panel and a light bar mounted at the very top of the panel or outside of the cockpit on the nose of the aircraft. The light bar should be in the pilot's direct field of vision, when looking forward from the cockpit. A series of lights on the bar help align the aircraft properly along the swath. In some systems the light bar displays other informations such as whether the spray is on or off. Before scheduling the spray operations, the team leader and the pilot must locate the coordinates of a series of points delineating the boundaries of the area to be spayed. This can be done by the ground team by hand-held GPS receiver. When this series of points is loaded into the GPS receiver of the aircraft, it will form a polygon which represents the spray plot. The team leader must also locate any excluded areas such as ponds, rivers, villages, etc."},{"index":2,"size":345,"text":"The GPS receiver of the aircraft will give the pilot the heading position to the spray area polygon. When the aircraft has reached that point, the pilot may, if possible, let the guidance system software choose the swath or one leg of the polygon can be flown in the desired direction, according to the wind direction. When the insecticide in the tank has been used, the GPS unit will record the shut off point and the system will give the direction back to the ait strip where the aircraft was loaded. After the aircraft has been reloaded, the GPS receiver will direct the pilot again to the spray plot and set up a swath which will start at the point where the previous spray ended, so no gap is left. The ability of GPS to accurately align each swath, helps to ensure uniform application throughout the designated spray plot. The system can record the spray aircraft's path, cross track error, the exact flow rate and whether the product is being applied. The flow rate information can be imported from a compatible flow monitoring system. It is preferable that the GPS unit include a screen in the cockpit which displays a moving map showing the outline of the spray block and the continuous path of the aircraft above it. These data enable the pilot to make immediate correction. After finishing the last swath over the block, the pilot can climb to a safe altitude and carefully scrutinize the screen displays for possible gaps between swath runs or other indications of unsprayed areas, which can be sprayed before leaving. After returning into the airstrip the pilot transfers the information stored in the aircraft's GPS unit, to a computer diskette or other storage media. The storage devices can transfer the information to a PC. The aircraft's path over the spray plot can be displayed to the ground team. They can determine whether the spray block has received the full coverage. If the team leader decides is needed, it can be made immediately while the aircraft is still available."}]},{"head":"Accurate guidance of spray runs","index":209,"paragraphs":[{"index":1,"size":123,"text":"Track guidance system provided by GPS technology is of high importance in the improvement of track spacing accuracy, without using land marks. It is possible to precisely run or fly without significant deviation from the pre-determined spray runs. Hence there is no need for field marking. The mobile GPS receiver may be used as a very efficient for vehicle guidance while treating (fig. 99 and 100). Thus it is possible to spray according to parallel runs visualised on the GPS receiver display. It is also possible to drive round, obstacles such as dunes, bushes, hillocks or hills and again step into the current track line. When the hectometric speedometer of the vehicle is working well, it is possible to do without flag people."},{"index":2,"size":26,"text":"When GPS traces together and corresponding way points, it is possible to accurately calculate the treated area and, hence, the exact dose of a.i. per ha."},{"index":3,"size":22,"text":"The benefit of GPS is even greater when it is integrated with a spray monitoring system linked to the vehicle speed (radar)."}]},{"head":"Inspection of treatments","index":210,"paragraphs":[{"index":1,"size":70,"text":"The object of acridid control operations is to control acridid populations by reducing their numbers. This object (acceptable acridid mortality) may be hindered by many uncontrolled factors, such as technical drawbacks, un-correct calibrations, logistic failures etc. Being completely certain that calibrations have been correctly figure 99. Layout of a pyrethroid spray. The trace irregularities are due to sand dunes that cross the spray tracks during which the spray was interrupted."}]},{"head":"142","index":211,"paragraphs":[{"index":1,"size":196,"text":"Locust Control Handbook done and a good chemical was applied at the right dose, is not sufficient. it is only the actual biological effect, noticed on the field, which is valid. Inspections of effectiveness are essential because of economic and environmental requirements. Any treatment which does not attain its target means pollution and obligation of treating again sometimes over a wide area. Furthermore, this entails a high risk for the situation to be beyond any control. It is absurd to treat tens of thousand hectares and notice afterwards that the product was not effective or the dose was not sufficient. Errors can be admitted in such complex operations but is not acceptable to neglect being provided with the means to be able to detect and overcome them before the consequences become irremediable. therefore, it is very import to include efficacy inspections within the control strategy and provide control teams with the means to enable them to check the quality of sprays. During large scale interventions, it is not necessary to undertake precise checking operations after each spray. However, detecting low efficacy as soon as it occurs necessitates taking preventive measures and undertaking inspections during control operations.  "}]},{"head":"Preventive measures","index":212,"paragraphs":[{"index":1,"size":44,"text":"The first measure is to meticulously perform the basic calibrations. Then checking spray quality should be executed consecutively to the basic calibrations, before starting any treatment. It is mainly a matter of visual estimations of density and droplet size as well as swath width."}]},{"head":"Post-treatment inspections","index":213,"paragraphs":[{"index":1,"size":40,"text":"The most desirable is to undertake routine checks of the efficacy after each treatment. During small-scale aerial operations, inspections may be undertaken by ground teams, meanwhile during large-scale operations, these tasks, as well as flagging, are entrusted to helicopter teams."}]},{"head":"Routine inspections","index":214,"paragraphs":[{"index":1,"size":41,"text":"Establishing routine inspections enables control teams to detect weaknesses as soon as they occur. thus, as soon as a treatment appears non efficient, samples can be taken to estimate the spray quality before suspecting the chemical. Among the causes of inefficacy:"},{"index":2,"size":22,"text":"• Incorrect calibration of one or more basic parameters. Checking basic parameters makes it possible to identify the cause of the default."},{"index":3,"size":74,"text":"• If atmospheric conditions are the cause of the default, treatments should be postponed until improvement of the weather conditions. • It is only when the accuracy of all calibrations is verified, the atmospheric conditions are fully suitable and the acridids are really attained by droplets that the chemical could be questioned. In this case, immediately stop spraying and report to the hierarchy. Meanwhile, if possible resume the operations with an alternative recommended chemical."}]},{"head":"Optimising factors of ground operations","index":215,"paragraphs":[{"index":1,"size":77,"text":"Acridid control consists of accomplishing different interdependent tasks, starting from signalling infestations to post treatment inspections. Any factor which interrupts the correct course of a task, might have a negative effect on the final result, i.e. the control of acridid infestations. The fact that aerial operations depend on the ground team support, emphasize the importance of optimising those factors, at all the chain levels. The correct use of ground means depends on the human and material factors."}]},{"head":"Intervention equipment","index":216,"paragraphs":[]},{"head":"Facts","index":217,"paragraphs":[{"index":1,"size":55,"text":"In Sahelian-Saharan zones, particularly during rainy seasons, ground displacement are very difficult and vehicles are often roughly handled. There are frequent breakdowns, sometimes final. The frequency of breakdowns depend on the equipment robustness but the span of immobilization varies with the availability of spare parts, the skill of the team and the scale of damage."},{"index":2,"size":208,"text":"The working of ground equipment is mainly linked to the state of the vehicles. Equipment depends on the vehicle limits and weakness. Thus, forward speed varies within 5 to 15 km/h (as maximum) and the emission height varies from 2 to 10 metres. Besides, qualitative performance of the vehicles has a great influence on the accuracy of sprays. Thereby, improvement of the former enhances the latter. For instance, a work accomplished by a vehicle equipped with a tachymeter and a hand accelerator is much more accurate. Unfortunately, so far almost all the vehicles used in acridid control are not equipped with these very useful devices. Many brands and models of all terrain vehicles have been recently used to carry sprayers. They are mainly Land Rover, gasoline and diesel; Toyota Land Cruiser, gasoline and diesel; Mitsubishi Pajero, gasoline and diesel; Mercedes Unimog and several other types of trucks. This great heterogeneity of brands and types inevitably entails an increase of breakdowns and a great variation of quantitative and qualitative performances. A given gear position does not correspond to the same forward speed with every all-terrain vehicle, whereas many operators shift from one vehicle to another and engage the same gear position, thinking that they work according to unchanged parameters."}]},{"head":"Improvements","index":218,"paragraphs":[{"index":1,"size":18,"text":"It is possible to alleviate the above disadvantages by giving more technical consideration to the purchase of equipment:"},{"index":2,"size":32,"text":"• Selecting vehicles and spray equipment. Vehicles for transportation and spraying should be selected according to technical criteria, among models and types which have already been thoroughly tested in acridid control areas."},{"index":3,"size":28,"text":"• homogenization of vehicles and spraying equipment. The great diversity of, brands and models requires keeping important stock of spare parts, which is costly and difficult to manage."},{"index":4,"size":74,"text":"• devices for improving spray accuracy. It is highly advisable that vehicles, which carry sprayers, be equipped with minimum improvements such as: handnotched accelerators, adding hectometric and a gyrating compass. Theses devices constitute an important optimization factor. Product and time saving entailed by accuracy, homogeneity and rapidity, largely offset the purchase and the installation costs. New technologies make it possible to provide more or less sophisticated devices such as GPS and spray monitoring system."}]},{"head":"Message transmission means","index":219,"paragraphs":[{"index":1,"size":58,"text":"Thanks to new technologies there are significant improvements in telephone communications. However telephone via satellites is still too expensive to be used for daily transmission routines. Therefore radiotelephone remains the major means of communication between teams and the management of acridid control, at local or national levels. For optimal use of radiotelephone, the following recommendations should be considered:"},{"index":2,"size":9,"text":"• each team should be provided with a radiotelephone;"},{"index":3,"size":16,"text":"• the daily transmission routine should be undertaken every day at fixed hours for each station;"},{"index":4,"size":33,"text":"• clear and concise messages should be transmitted according to standardised procedure. The document where messages are recorded should be the same for all teams and be clear and easy to be kept;"},{"index":5,"size":9,"text":"• head quarter base should permanently be tuned in."}]},{"head":"The human factor","index":220,"paragraphs":[{"index":1,"size":31,"text":"Considering that acridid operation sites are very often remote and under tyring climate, particular attention should be given to the material organisation as well as to the skill of the staff."}]},{"head":"Equipment problems","index":221,"paragraphs":[{"index":1,"size":65,"text":"The good spirit of teams in operation should not be altered by bad preparation of the assignment. Vehicles and spray equipment should be checked before departure for the operation sites. It is of high importance to provide a minimum number of tools and spare parts. Camping equipment, particularly tents and bedding, should be chosen with care so as to provide the staff with good rest."}]},{"head":"Skill of the staff","index":222,"paragraphs":[{"index":1,"size":165,"text":"Each staff member, whatever may be his level or job, should accomplish his task with skill. Therefore every one should be given the relevant training corresponding to his job. the team leader He should be educated on acrid bio-ecology. Trained on the use of radiotelephone and on the desert navigation, with and without GPS. The team leader should master the anti-locust application techniques and post-treatment inspections. He should be well-trained on the negative effects and impacts, both on humans and the environment. drivers They should have the basic knowledge on mechanics which enables them to understand the functioning of the vehicles. They should be able to fix, on the spot, the usual breakdowns. No driver should be sent for a survey or treatment assignment without being consistently trained on all-terrain driving on muddy or sandy tracks. Labourers Each worker should be trained to accomplish properly his task, even those considered as very simple. It is particularly vital that the insecticide handlers take usual safety measures."}]},{"head":"Optimising factors of aerial interventions","index":223,"paragraphs":[{"index":1,"size":25,"text":"The optimal use of aircrafts depends on two main factors. The first is of strategic nature: infrastructure and the other is of organizational nature: logistics."}]},{"head":"Infrastructure","index":224,"paragraphs":[{"index":1,"size":103,"text":"Each country likely to be seriously affected by acridids (locust or grasshoppers) should build a relevant number of airstrips, within a network which can be integrated into an acridid control strategy (Duranton et al., 1989). This network should be composed of one main airbase, a few secondary and several backup airstrips. This infrastructure may be integrated in a global preventive system (fig. 101). the main airbase In most cases it could be an airport with a permanent civil activity. A permanent stock of fuel, lubricants and insecticides will be kept there, as well as spare parts for routine and statutory maintenance of aircrafts."}]},{"head":"Secondary airbases","index":225,"paragraphs":[{"index":1,"size":75,"text":"They are linked to the main airbase. They should be usable in all seasons, so they must tended regularly and maintained. Secondary airbases should keep additional fuel and lubricant stocks as well as all the logistics for aircraft servicing in case of the need for emergency locust outbreak control. The secondary air bases are also the offices of the preventive control teams which are the kingpin of the locust control strategy especially the Desert locust.  "}]},{"head":"Ground support","index":226,"paragraphs":[{"index":1,"size":271,"text":"Aerial operations will only be successful if ground support is sufficient. So, before starting operations, it is of high importance to make sure that all aspects of the ground support have carefully been studied. This is a prerequisite condition to guarantee the success of aerial interventions. therefore ground support is a fundamental factor, because it determines the success or the failure of anti-acridid operations. Any mistake in signalling or locating infestations or any default in the supply management, will result in a waste of time which can lead to suspending operations. If aerial applications are correctly organised, they may have a reasonable cost; but they rapidly become prohibitive if aircrafts are obliged to make long ferry flights or if they are often stuck on the ground for lack of foresight. In case of logistic failure, aerial means may become a hindrance to the efficacy of the whole of an anti-locust campaign. It is the ground team leader who defines spray parameters, i.e. the volume of application, the droplet size, the track spacing and the area to be treated. The pilot is responsible for the flight security and the spray quality (Muller, 1985). Together with the ground team, the pilot organises the lay out of treatment and the calibration of the spraying system. It is critical that a good spirit reigns between the pilots and ground teams. Pilots have to consider the constraints which weighs on ground teams and vice-versa. Ground team have to respond to the requirements of the aircraft running. This is a sine qua non condition for the success of aerial operations. Ground teams should fulfil the following tasks."}]},{"head":"Localizing target areas","index":227,"paragraphs":[{"index":1,"size":118,"text":"The pilot should know precisely, before each takeoff, where he should spray. He should not lose time searching for the target zone. Imprecise description of location which often results in spraying of non target areas, can now be avoided thanks to GPS. Pilots and ground teams should be provided with the same maps with a suitable scale (1/200000 or, if missing, 1/500000) for local topography. It is sometimes useful to use landmarks to delimit areas to be treated. Sometimes, Desert locust hopper bands could be seen, thanks to their bright yellow colour, in contrast with green vegetation. However, at the end of rainy season, their colour may be confused with drying spots of vegetation already consumed (Monard-Jahiel, 1989)."}]},{"head":"Marking out and flagging","index":228,"paragraphs":[{"index":1,"size":143,"text":"In many cases pilots can identify land marks reported on maps. But in Sahelian zones it is not wise to rely only on the position of certain villages reported on maps especially because few new maps of the Sahel are available. Many villages have disappeared or changed their location. Other villages are new and not reported on maps. In all cases GPS are now the most reliable tools for undertaking this task and with gpS track guidance there is no more need for flagging. In the absence of GPS, several methods of flagging are used but none is perfect in all cases. Among the most currant: the use of the lay of the land The process is suitable when the target area is large enough and well delimited by tracks, reliefs, canals and rivers which could be used as markers by the pilot."}]},{"head":"the use of flags","index":229,"paragraphs":[{"index":1,"size":118,"text":"This method is more accurate whenever flag holders are available, especially when large areas are concerned. Flags of about 1 m are white, yellow or orange coloured. Flag holders (fig. 102) move quickly from a flight pass to the next as the aircraft progresses. They must move as soon as they see that the aircraft is flying towards them, before it flies above; then they move upwind and stop at the peg stuck beforehand, at track spacing distance (fig. 103). the use of smoke When waste tyres are available, it is possible to create a source of smoke that could enable the pilot to easily spot the target zone. This method is not suitable for marking spray tracks. "}]},{"head":"Supply","index":230,"paragraphs":[{"index":1,"size":114,"text":"Supplying acridid control operations is often very difficult because operations almost always take place in remote zones, far from urban centres. However, difficulties should never be a justification for interrupting treatments. Running out of fuel, lubricants or insecticides may have serious consequences on the evolution of control operations. it is recommended to provide, long before needed, strategic stocks of fuel and insecticides in areas subject to frequent outbreaks. During control campaigns each unit should be provided by communication and transport means so that they could have the autonomy of action as large as the importance of the affected area, especially when the distance to the supply source is greater and/or the tracks are rough."}]},{"head":"Aircraft serving","index":231,"paragraphs":[{"index":1,"size":65,"text":"Aircraft servicing comprises several operations including fuelling, loading insecticides and daily routine maintenance. Aircraft servicing tasks require high security conscientiousness together with celerity, taking into account the strict procedure of fuelling and loading insecticides. Therefore these tasks should be performed by skilled and scrupulous people. requirement pertaining to fuels • Aircraft fuel barrels should be original. They must be refused if they are not capped."},{"index":2,"size":11,"text":"• Check for humidity as soon as the barrels are opened."},{"index":3,"size":48,"text":"• Refuelling should be made after each landing -even in the evening -with adapted and complete tools (chamois leather, large funnel provided with a tap and a thin gauze). requirement pertaining to insecticides • Operators, particularly insecticide handlers, should wear adapted, light and efficient protective clothing (fig. 104)."},{"index":4,"size":26,"text":"• Insecticide loading should be made at a flow of 400 l/min, just before takeoff. This task should be executed with celerity but without excessive haste."},{"index":5,"size":23,"text":"• Formulations should be filtered. For this purpose, use appropriate tools such as a decanting tub and thin gauze at the hose tips."}]},{"head":"Organisation and steering of a temporary acridid control air base","index":232,"paragraphs":[{"index":1,"size":81,"text":"The location of fuelling pit should be conscientiously weeded so as to avoid any risk of fire. Barrels should be 10 m away from the air strip. A large foam extinguisher, maintained in perfect state and fixed on a trolley, is placed close to refuelling pit, together with a shovel and a mattock. A wind sock is also erected in the place. It allows the pilot to permanently visualise the direction and the wind force before takeoff and landing (Castel, 1982)."}]},{"head":"Location of the fuelling pit","index":233,"paragraphs":[{"index":1,"size":92,"text":"A loading station is placed at each end of the air strip (fig. 105), which enables aircrafts to take off upwind whatever be its direction (aircraft should not turn with full cargo). When the strip is less than 500 m, only one pit is set up at the end opposite to the dominant wind so that the aircraft could take off directly after having been loaded. During the rainy season in Sahelian zones, prevailing winds are West to South-West. So, the unique tip should place at the eastern, end of the strip."}]},{"head":"Loading pumps","index":234,"paragraphs":[{"index":1,"size":59,"text":"Distinction should be made between the fuel pump and insecticide pump. Even when a single aircraft is in operation, it is always preferable to provide two specific pumps. They should be self-primed with a capacity of 400 l/min under low pressure. A few spare -manual pumps should be provided so that it is possible to compensate any pump breakdown. "}]},{"head":"Maintenance","index":235,"paragraphs":[{"index":1,"size":80,"text":"The maintenance specific to aircrafts is undertaken under the responsibility of the pilot or the aircraft engineer. When planning acridid control programs, consideration should be given to the maintenance routine. Some servicing sequences are submitted to VERITAS checking and other are to be undertaken in registered workshops which are, sometimes, situated far away from control operation fields. Even some affected countries do not have such institutions. Equipment used in acridid control suffers from rough conditions and the rhythm of work:"},{"index":2,"size":16,"text":"• atmospheric and climatic conditions are tiring for people and equipment (oppressive heat, sand storms, turbulences),"},{"index":3,"size":16,"text":"• highly concentrated formulations of insecticides which are often corrosive for rubber washers, metals and paints,"},{"index":4,"size":18,"text":"• high rhythm of working for controlling grasshopper pullulations or locust upsurges. Thus, the maintenance routines become essential:"},{"index":5,"size":20,"text":"• At the end of the day, no product should remain in the spraying system nor in the aircraft tank."},{"index":6,"size":15,"text":"• The tank and the formulation circuits should be flushed and cleaned without being dismantled."},{"index":7,"size":19,"text":"• Aircrafts should be regularly washed with soapy water, under the supervision of the pilot or the aircraft engineer."}]},{"head":"General links","index":236,"paragraphs":[{"index":1,"size":54,"text":"Plague locusts and grasshopper pullulations may affect large areas and territories. Aerial control teams may have to operate in remote zones where usual telephonic communications are rather rare or, even, non existent. In regards to satellite telephone, it is too expensive to equip all the operating teams. So, radio communications are necessary to ensure:"},{"index":2,"size":8,"text":"• relations with local civil and military authorities;"},{"index":3,"size":6,"text":"• in flight safety of aircrafts;"},{"index":4,"size":7,"text":"• co-ordination with other locust control units;"},{"index":5,"size":7,"text":"• relations with locust control head quarters;"},{"index":6,"size":10,"text":"• relations with central and regional Plant Protection head quarters."},{"index":7,"size":97,"text":"Radio sessions should be scheduled for, at least once a day, at fixed hours except for emergencies. Messages should be recorded on a register kept by the head of the aerial unit. It is the job of the head of the unit to keep permanent contact with the local authorities so that local populations are informed and take the usual protective measures when dangerous products are used. It is particularly recommended that wells and private reservoirs are sheltered and children do not stay in the open air. Livestock should not stay on pastures due to be sprayed."}]},{"head":"Accommodation and subsistence of the staff","index":237,"paragraphs":[{"index":1,"size":101,"text":"The tiring conditions which weigh heavy on the staff are to be taken seriously. So, the material means should be provided, whenever possible, so as to alleviate these effects. Special attention should be given to the flying staff. Good restful conditions are necessary. Therefore, the elementary requirement for everybody should be satisfied, i.e.: • a healthy diet, varied and sufficient, served at fixed hours; • a minimum and decent comfort, respecting the privacy and the belief of people (spacious tents in a sufficient number); • a regular timing; • a collective and firm discipline and a special care for individual problems."}]},{"head":"Management problems","index":238,"paragraphs":[{"index":1,"size":47,"text":"Good management is an essential optimisation factor. The management scheme should be conceived so that operations are positively viewed and not considered as drudgery. The forms should be clear as well as simple. Colligated information should be exact and accurate. There are two aspects of the management:"}]},{"head":"Steering the operations","index":239,"paragraphs":[{"index":1,"size":64,"text":"The head of the unit should be capable of taking the decisions required by the daily management of his staff, without permanently asking for support from his hierarchy. The head of the unit should be skilled enough to assume and supervise the following necessary technical tasks: • calibrate spraying systems, according to the needs of atmospheric conditions and with the collaboration of the pilot."},{"index":2,"size":14,"text":"• Know the physicochemical properties of the product used and the relevant safety measures."},{"index":3,"size":19,"text":"• ensure, with the collaboration of the pilot, that signalling operations are undertaken correctly and according to flight regulations."},{"index":4,"size":15,"text":"• ensure that supply and maintenance operations are correctly promptly executed, while respecting safety measures."},{"index":5,"size":18,"text":"• regularly check the efficacy and the spray quality. Take immediately relevant measures in case of efficacy problem."},{"index":6,"size":13,"text":"• co-ordinate and supervise the activities of survey, signalling and the base camp."},{"index":7,"size":17,"text":"• report to the hierarchy about the progress of the operations and the locust (or grasshopper) infestations."}]},{"head":"Keeping the campaign record","index":240,"paragraphs":[{"index":1,"size":24,"text":"This document is very important and should be kept update by the head of the unit. The following items should particularly be noted down:"},{"index":2,"size":10,"text":"• events, such as incidents accidents, treatment results, signalling, etc."},{"index":3,"size":10,"text":"• movements of consumables (fuels, lubricants, spare parts, chemicals, foodstuffs)."},{"index":4,"size":75,"text":"• detailed progress of technical operations. Keeping accurate records is of great importance for making a comprehensive assessment of the campaign, which enables locust operators to draw conclusions for improving the following campaigns. Besides, the pilot keeps the ship's log in which all treatment technical data are recorded. When this book is correctly kept, it could be a valuable source of data for improving future aerial interventions and assessing the actual costs of aerial operations."}]},{"head":"Conclusion 155","index":241,"paragraphs":[]},{"head":"Conclusion","index":242,"paragraphs":[{"index":1,"size":87,"text":"Curbing locust plagues demands rapid treatment of vast areas, which requires rapid responses and carefully coordinated response teams far from each other, which imposes to rapidly mobilise very important logistic means. To rise to the challenge, locust operational research has focussed on decreasing the volume of application. Hence, it is not surprising that the ULV technique was invented for the particular needs of locust control, before being adopted and developed by forestry and other fields of plant protection. This success is understandable if we consider the following:"},{"index":2,"size":22,"text":"• the efficacy of a spray is improved when droplet size is decreased together with the increase in the number of droplets."},{"index":3,"size":11,"text":"• coverage of 20 droplets per cm² sufficiently controls acridid infestations."},{"index":4,"size":24,"text":"• these findings enable considerable reduction of volumes of application per hectare, thus decreasing the logistic costs and allowing the optimization of spray equipments."},{"index":5,"size":20,"text":"• oily droplets are more effective than water-based droplets at adhering to plant and insects, thus the efficacy per dose."},{"index":6,"size":30,"text":"• the simplicity and the reliability of the technique make it possible to design simple, light and robust sprayers some of which can be used by farmers or unskilled applicators."},{"index":7,"size":60,"text":"Since the invention of the ULV technique, important progress has been made in making equipment more reliable. The introduction of hand-held ULV sprayers at the farmer's level enables them to take charge of the protection of their own crops. The newly introduced vehicle-mounted electrical sprayers, are considered, by preventive control teams, as a reliable substitute for the exhaust nozzle sprayer."},{"index":8,"size":95,"text":"The introduction of microcomputers, GPS and radar for monitoring spraying parameters is an asset for the optimal use of either aerial and ground operations. Nonetheless, these technologies will not be routinely utilised in the field unless the defects, revealed by the use in rough conditions, are corrected. Furthermore it is recommended that the manufacturers reduce, as much as possible, the number of wearing spare parts. They should also adopt a minimum harmonization, so that some basic spare parts are the same. It is particularly advisable that the electrical connexions should be of the same type."},{"index":9,"size":58,"text":"Regarding the applications, it is of paramount importance to give great consideration to inspections of the spray quality, because many accidental and atmospheric factors may alter operation progress. Therefore it is advisable to systematically provide control teams with the necessary tools to correctly accomplish these tasks. Automatic image analysis will only be made when thorough study is required."},{"index":10,"size":62,"text":"Accomplishing correct sprays does not only depend on the equipment quality and its good use. The physico-chemical properties of insecticides also have determinant roles on the spray quality. The lack of standards hampers a possible harmonization of the physical specification of formulations. This make it difficult for establishing abacus which are, yet, an ideal tool for simplifying the use of spray equipment."},{"index":11,"size":70,"text":"PHOTOS Schistocerca gregaria (Forskål, 1758), drawings pages 44, 95, 154 and 156, after Jules Künckel d'Herculais, 1905. Invasion des acridiens, vulgo sauterelles, en Algérie (1893-1905). Imprimerie administrative et commerciale Giralt, Alger. 3 Vols. It is of paramount importance to improve application techniques when controlling locust outbreaks in developing countries. Most available documents and publications on locust control deal mainly with insecticides, rather than application techniques and the required control equipment."},{"index":12,"size":78,"text":"The present guide book is designed to make up for this oversight. Basic principles for conducting spraying operations, descriptions of spraying equipment -especially for ultra low volume sprayingand specific locust control techniques are described in detail. The document explains how to get the most from treatments while minimizing the adverse effects to man and the environment. This book is aimed at decision-makers and all those involved in locust control who wish to improve their knowledge of application techniques."},{"index":13,"size":49,"text":"Tahar Rachadi is a research engineer in locust ecology and control within the BIOS Department at Cirad, Montpellier (France). Since 1986, he has been involved in popularizing ultra low volume application techniques in Madagascar and China as well as in some areas of Africa, Middle East and Central Asia. "}]}],"figures":[{"text":" in many developing countries is tenuous at best due to increasing population and climatic change which creates further challenges in what are often already marginal conditions for food production. Locust outbreaks and grasshopper outbreaks can dramatically reduce crop yields and instigate mass food shortage. "},{"text":"figure 1 . figure 1. A hopper band of Desert locust (5th instar) crossing a road in Senegal (October 1988). Hopper bands of Desert locust may have a density of several hundreds of hoppers per square metre and may cover tens of hectares. "},{"text":" x 1,000) / C where: Q = the quantity expressed in ml D = the dose expressed in grams of a.i. per ha C = active ingredient content of original formulation Case of the Desert locust: Q = (200 x 1,000) / 450 = 444 ml Case of the grasshoppers: Q = (150 x 1,000) / 450 = 333 ml "},{"text":"figure 3 . figure 3. Large drops are poorly retained by the vegetation cover and generally end up on the soil (after Hoechst). "},{"text":"figure 2 . figure 2. Relationship between droplet diameter and number (after Hoechst). For the same volume, dividing the diameter by two results in multiplying the area covered by two. "},{"text":"figure 7 . figure 7. Diagrammatic representation of the volume median diameter (VMD) and the number median diameter (NMD) (afterDobson, 2001). Half of the volume of the spray is composed of droplets smaller than the VMD and half is larger than VMD. Half of the total volume composed of small droplets contains a signifi cantly greater number of droplets than the half containing the largest droplets. "},{"text":"figure 10 . figure 10. Orientation of hydraulic energy nozzles and its effect on the droplet size in aerial spraying(after Ciba-Geigy, 1984). "},{"text":"figure 11 .figure 14 . figure 11. Two shapes of restrictors of pneumatic sprayers (after Musillami, 1982). a: liquid circuit b: restrictor for high velocity air "},{"text":" figure 18. Droplet production by a rotating and toothed disk (after Dobrowsky and Lloyd inMatthews, 1985). "},{"text":"figure 21 . figure 21. Evaluation of wind force with Beaufort scale. "},{"text":"figure 26 . figure 26. Sensitive papers pinned directly within the canopy at different heights of a shrub like plant (after Ciba-Geigy). "},{"text":"figure 28 .figure 29 . figure 28. Standard cards for visual assessments of ULV spraying. figure 29. Standard cards for visual assessments of VLV spraying. "},{"text":" figure 32. Droplet density profi le on three plots treated with the same formulation and the same amount per hectare. Experiments performed by CIRAD team in Chad in 1988 (3 l/ha of a ULV formulation applied by hand-held sprayer). Ten collectors were aligned in each plot. "},{"text":" figure 35. Operating diagram of a gaseous energy nozzle with detail of the restrictor (after Musillami, 1982). "},{"text":"figure 37 . figure 37. Backpack mist blower fi tted with AU8000 spray head (after Micronair). Power is supplied by the airstream produced by the mist blower. The hose might be positioned vertically for Controlled Drift Spraying. "},{"text":"figure 39 . figure 39. Micronex rotating cone for backpack sprayers (after Micron Sprayers). "},{"text":"figure 40 . figure 40. Layout of hand-held ULV sprayers (after Micron Sprayers). "},{"text":"figure 44 . figure 44. The Puma sprayer set showing an articulation, enabling the vertical position of the air stream outlet. The air stream pipe might be horizontal (A) for air carrier spraying or vertical (B) for controlled drift spraying. "},{"text":"figure 46 . figure 46. Spray droplet size against atomiser rotational speed (after MicronSprayers). The most suitable rotational speed for acridid control ranges from 4,000 to 5,000 rpm. All measurements were made with water, hence the indications are given as basis for further calibrations to be made with actual formulation. "},{"text":"figure 48 . figure 48. Description of the principal components of the Ulvamast (after Micron Sprayers). "},{"text":" figure 50. Diagram of a typical aircraft spray system. "},{"text":"figure 51 . figure 51. Helicopter with twin tanks equipped with a hydraulic nozzle spray boom. "},{"text":"figure 52 . figure 52. Centrifugal pump functioning (afterMusillami, 1982). "},{"text":" figure 55. Cross-section of a roller pump (afterMatthews, 1979). "},{"text":"figure 56 . figure 56.Air-driven pump (after Shell,  1983). It is fi xed under the fuselage, behind the aircraft propeller. 1: brake cable; 2: outlet; 3: inlet; 4: pump casing; 5: adjustable blades. "},{"text":" Two types of regulators are mounted on aircrafts: a. Sorensen type valve (fig.57) The variation of pressure is obtained by tightening a spring (2) of a teflon needle (3) which controls the return of liquid to the tank. The command button (1) of the needle is located in the cabin within the reach of the pilot's hand. The start and the stop of the spray is operated by a simultaneous action of the outlet (4) and return valves (5).1: command button; 2: spring; 3: tefl on needle; 4: outlet valve; 5: return valve; 6: inlet; 7: back to the tank; 8: outlet. figure 57. Layout of Sorensen type valve (after Sorensen). "},{"text":"figure 58 . figure 58. Three-way valve (afterShell, 1983). "},{"text":" figure 60. Position of the components of an airplane spraying system (afterShell, 1983). "},{"text":"figure 61 . figure 61. Fitting of different nozzles on spray booms (afterShell, 1983 and Micronair, 1987). "},{"text":" lter; 2: pump; 3: inlet; 4: fl ow regulator; 5: manometer; 6: spray valve; 7: spray head; 8: tank. figure 65. Layout of Micronair spray heads (afterMicronair, 1986). "},{"text":" figure 66. Fitting of a Micronair spray head (afterMicronair, 1986). "},{"text":" figure 67. Viewpoint of a Micronair spray head (afterMicronair, 1986). "},{"text":" figure 68. Diagram of a check valve (after Micronair, 1987). "},{"text":" figure 69. Diagram of VRU (after Shell, 1983). "},{"text":"figure 70 . figure 70. Fixed orifi ce plate (afterMicronair, 1987). "},{"text":"figure 73 . figure 73. Graph of droplet size vs. rotational speed (afterMicronair, 1986). The droplet size may vary or be reduced with many oil-based and ULV formulations as shown by the shaded band. A check should always be carried out with the actual chemical being used. "},{"text":"figure 74 . figure 74. Adjusting blades angle for Micronair spray heads AU5000 and AU5000-2 (after Micronair, 1897). "},{"text":"figure 75 . figure 75. Front panel of application monitor (after Micronair). "},{"text":"1 : inlet; 2: defl ector; 3: mist; 4: cage; 5: clamp collar; 6: fi xing the cage to the boom. A: layout of spray head with regards to displacement of the airplane. figure 77. Diagram of Beecomist spray head (after Quantick, 1985). "},{"text":"figure 79 . figure 79. Layout of basic procedure of blanket treatment of a hopper band with vehicle-mounted sprayers. "},{"text":"figure 81 . figure 81. Treatment of a hopper band marching crosswind (after Steedman, 1988). "},{"text":"figure 83 . figure 83. Frequency of bad calibrations of ground equipment in acridid control (after SAS Letter, 18/89,Prifas, 1989). Ineffectiveness of treatments are mainly due to bad calibrations. "},{"text":"figure 85 . figure 85. Tools and devices to perform correct calibrations and checking. "},{"text":" of application (v) litres per hectare V = 600 x F / T x S 2 -Flow (f) rate or output litres per minute F = S x T x V / 600 3 -Forward speed kilometres per hour S = 600 x F / T x V "},{"text":" 5 km/h and the track spacing (T) is 30 m, what should be the output (F)? F = 3.5 x 30 x 5 / 600 = 0.875 l/min 2nd example: the same formulation is used against the same target (V = 5 l) by means of a vehicle-mounted sprayer which has a forward speed of (S) 12 km/h. What should be the output (F) if the track spacing is (T) is 75 m? F = 12 x 75 x 5 / 600 = 7.5 l/min 3rd example: a helicopter is going to spray the same target the same product (V = 5 l). Considering that the fl ying speed (S) during treatment is 140 km/h and the track spacing (T) 100 m, what should be the global the fl ow rate (F)? F = 140 x 100 x 5 / 600 = 116.66 l/min "},{"text":" figure 87. Maximum emission height with hand-held ULV sprayer (afterMatthews, 1985). The emission height for portable sprayers, varies generally from 1 m (above emerging plants) to 7 m (with mist blowers, air fl ow upwards). Track spacing varies from 5 to 60 m, according to the emission height and the speed of lateral wind (fi g. 88 and tab. XXXI). "},{"text":"figure 89 . figure 89. Mode of displacement for controlled drift spraying with motorized mist blowers. The operator walks straight forward at a regular speed. "},{"text":"figure 90 . figure 90. A diagram of showing track spacing with overlapping swaths (after Matthews, 1985). "},{"text":"figure 92 . figure 92. Diagram of the operator advance during treatment with hand-held ULV sprayers (afterMatthews, 1985). "},{"text":" checking utilities • implements and tools described above, • some clean rags, • a roll of soft paper (toilet paper could be good), • soap, • a container of diesel or solvent. a: by means of a torch; b: by means of a torch bulb; c: by means of a voltmeter figure 93. Checking battery condition of hand-held ULV sprayers (after Ciba-Geigy, 1984) 122 Locust Control Handbook checking the good working order of the sprayer To ensure a good working order of the sprayer, regular checks are necessary: "},{"text":"D figure 96. Adjustment of emission height according to wind speed (after Ciba Agrochemicals, 1969). H x U should remain constant. When the wind speed doubles, the emission height must be lowered by half. "},{"text":" flying speedIt depends on the aircraft specifications. For a given aircraft it seldom varies (tab. XXIV and XXV).track spacing and emission heightThese two parameters are interdependent. To determine them, see tableXL.global output It depends on the volume of application, the flying speed and the track spacing. The global output can be calculated by using the following formula: f = S x t x v / 600 the output of each spray head It equals to the global output (f), divided by the number (n) of spray heads: output of each spray head = f / n micronair settings: refer to table XXVI and, according to the model choose the orifice (of the VRU) and the corresponding pressure. If necessary change the orifice plate of the VRU. calibration of droplet size Refer to droplet size graph. Diagram shows droplet size versus rotational speed. Refer to the tables showing the setting of fan blades (fig. 73). "},{"text":"figure 100 . figure 100. GPS tracks of a barrier treatment demonstration in Guzor region, Uzbekistan. The area was very sloping and undulating. "},{"text":" temporary bases They usually are fitted out near the villages where survey teams (within preventive control systems) are based. The airstrip usually consists of bare earth without vegetation. They are used periodically, during outbreak or plague periods, when survey and control activities are very frequent. A strategic stock of fuel and lubricant should be kept where tracks are not feasible during rainy seasons. "},{"text":"figure 101 . figure 101. Diagram of Desert locust preventive control system (afterDuranton et al., 1989). "},{"text":"figure 102 . figure 102. Flag holder wearing protective clothes (after Ciba-Geigy). "},{"text":"figure 103 . figure 103. Successive positions of fl ag holders (E) (after Lancon et al., 1986). "},{"text":" figure 105. Layout of different working posts on a temporary locust control air base (afterShell, 1983). "},{"text":"p. 5 : Calliptamus italicus, (Linnaeus, 1758), © Antoine Foucart, Cirad. p. 7: Bryophyma debilis (Karsch, 1896), © My-Hanh Luong-Skovmand, Burkina Faso, Cirad. p. 45: Gregarious male desert locust, Schistocerca gregaria (Forskål, 1758), © Annie Monard, Cirad. p. 97: Mating of migratory locusts, Locusta migratoria (Linné, 1758), 2006, © Michel Lecoq p. 155: During the 1988 invasion, a swarm of Schistocerca gregaria fl ying over an island of Archipelago Cape Verde, © Maurice Balmat, FAO. "},{"text":" Cover. Controlled drift spraying against Moroccan locust in Uzbekistan with a vehicle-mounted sprayer, © T.Rachadi, April 2007.    "},{"text":"  "},{"text":"  "},{"text":"  "},{"text":"  "},{"text":"  "},{"text":"  "},{"text":"table i . Classification of sprays according to the volume of application per hectare. type of spray Quality of spray volume (l/ha) typical droplet size (µm) type of sprayQuality of sprayvolume (l/ha)typical droplet size (µm) High volume Coarse 600 -1,000 > 500 High volumeCoarse600 -1,000> 500 Medium volume Coarse 100 -600 300 -500 Medium volumeCoarse100 -600300 -500 Low volume Medium 25 -100 200 -300 Low volumeMedium25 -100200 -300 Very low volume Fine 5 -25 50 -150 Very low volumeFine5 -2550 -150 Ultra low volume Very fi ne < 5 40 -60 Ultra low volumeVery fi ne< 540 -60  "},{"text":"table vi . Flight time of droplets emitted by fan nozzles (afterDirske, 1986).  "},{"text":"table vii . Example of variation of droplet diameters in relation to the fl ow rate increase of mist blower knapsack sprayer (after  "},{"text":"table viii . Effect of rotational speed and the fl ow rate on droplet spectrum, with hand-held ULV sprayer Mini ULVA (afterDirske, 1985). revolutions rounds/min flow rate (ml/min) vmd (microns) nmd (microns) vmd/nmd revolutions rounds/minflow rate (ml/min)vmd (microns)nmd (microns)vmd/nmd 9,000 8.5 64 40 1.6 9,0008.564401.6 12,000 8.5 54 33 1.6 12,0008.554331.6 15,000 8.5 41 32 1.4 15,0008.541321.4 9,000 26.0 71 50 1.3 9,00026.071501.3 12,000 26.0 52 39 1.4 12,00026.052391.4 15,000 26.0 45 33 1.7 15,00026.045331.7 9,000 60.0 81 55 1.5 9,00060.081551.5 12,000 60.0 60 38 1.6 12,00060.060381.6 15,000 60.0 64 37 1.7 15,00060.064371.7    Spraying Principles 25 Spraying Principles25  "},{"text":"table iX . Atomisation method and droplet transport.  "},{"text":" The wind speed is measured by means of an anemometer. Wind anemometers can be sophisticated and have a digital display (fig.19). There are also less accurate, but simpler, devices which give a good indication of wind speed such as a Dwyer droplet size (microns) figure 19. Digital display anemometer. It displays the mean wind speed Sedimentation velocity time for 10 m falling (seconds) droplet size (microns) figure 19. Digital display anemometer. It displays the mean wind speed Sedimentation velocitytime for 10 m falling (seconds) 20 40 calculated over 30 consecutive seconds. 0.012 0.047 833 208 20 40 calculated over 30 consecutive seconds.0.012 0.047833 208 50 0.073 137 500.073137 60 0.105 98 600.10598 70 0.141 71 700.14171 80 0.183 53 800.18353 90 0.228 44 900.22844 100 0.278 36 1000.27836 120 0.355 28 1200.35528 140 0.445 22 1400.44522 160 0.536 18 1600.53618 180 0.625 16 1800.62516 200 0.705 14 2000.70514 250 0.940 10 2500.94010 300 1.150 8 3001.1508 Locust Control Handbook   Locust Control Handbook  "},{"text":"table Xi . Limits of Beaufort scale use for estimating wind force in controlled drift spraying (after  "},{"text":"do not deposit on the target zone. figure 24. Periods suitable for controlled drift spraying, in relation to the daily variations of atmospheric stability figure 23. Air stability and its figure 23. Air stability and its consequences on the quality of consequences on the quality of aerial spraying, in relation to aerial spraying, in relation to thermal conditions (after Castel, thermal conditions (after Castel, 1982). 1982). A: Inversion; air is stable, lateral A: Inversion; air is stable, lateral wind is regular; good conditions wind is regular; good conditions for drift spraying. for drift spraying. B: Neutral conditions; inversion B: Neutral conditions; inversion above; spray may still be above; spray may still be acceptable. acceptable. C: Conditions of turbulences; C: Conditions of turbulences; air movements are unstable and air movements are unstable and upward; drift spraying should be upward; drift spraying should be avoided: droplets avoided: droplets  "},{"text":"table Xii . Flow rate of spraying system \"Tee Jet nozzles\" with different viscosities of oily formulations (litres per minute, afterCastel, 1982b). Pressure Pressure (psi) (psi) table Xiii. Example of some liquid viscosity at 20° C. table Xiii. Example of some liquid viscosity at 20° C.  "},{"text":"nozzle d 4 fan 45 nozzles d 6 -d 7   Fenitrothion ULV 500 g/l Fenitrothion ULV 1250 g/l Diesel oil Fenitrothion ULV 500 g/l Fenitrothion ULV 1250 g/l Diesel oil Fenitrothion ULV 500 g/lFenitrothion ULV 1250 g/lDiesel oilFenitrothion ULV 500 g/lFenitrothion ULV 1250 g/lDiesel oil 40 1.29 1.36 1.48 2.05 1.76 2.20 401.291.361.482.051.762.20 50 1.48 1.57 1.66 2.36 2.20 2.45 501.481.571.662.362.202.45 60 1.62 1.78 1.82 2.58 2.32 2.75 601.621.781.822.582.322.75 70 1.80 1.95 2.02 2.84 2.60 2.68 701.801.952.022.842.602.68 80 1.89 2.03 2.15 3.08 2.80 3.10 801.892.032.153.082.803.10  Liquid   viscosity (cp)  Liquidviscosity (cp)  Water Pyrethroids Dursban 1.5 ULV Gas oil Fenitrothion 500 ULV Adonis 4 ULV Adonis 123.5 ULV Technical Malathion   1 6 -7 12 -14 28 4 -6 6 5.6 30 -40  Water Pyrethroids Dursban 1.5 ULV Gas oil Fenitrothion 500 ULV Adonis 4 ULV Adonis 123.5 ULV Technical Malathion1 6 -7 12 -14 28 4 -6 6 5.6 30 -40  "},{"text":"table Xiv . Marking characteristics of solvents on oil sensitive paper CF1 (after Ciba-Geigy, 1994).  "},{"text":"Solvents and other carriers marking characteristics*  Benzine (car gasoline)   Benzine (car gasoline) Castor oil   Castor oil Cottonseed oil   Cottonseed oil Cyclohexanone   Cyclohexanone Dibutylphtalate   Dibutylphtalate Diesel oil   Diesel oil Dimethylformacide   Dimethylformacide Dimethylphtalate   Dimethylphtalate Dioctylphtalate   Dioctylphtalate Ethanol   Ethanol Hexylene glycol   Hexylene glycol Isophoron   Isophoron Isoprpanol   Isoprpanol Kerosene   Kerosene Methanol   Methanol Methyltriglycol   Methyltriglycol Paraffi n oil   Paraffi n oil Pine oil   Pine oil Shelsol AB   Shelsol AB Solvent 200   Solvent 200 Soybean   Soybean Toluene   Toluene Trichlorethane   Trichlorethane xylene   xylene * 1: marks well 2: marks poorly 3: does not mark * 1: marks well2: marks poorly3: does not mark  "},{"text":"back to tank figure 34. Arimitsu knapsack mist blower (Nigerian-Canadian Cooperation, 1987). 1: pesticide tank 10: air pressure hose 1: pesticide tank10: air pressure hose 2: tank lid 11: insecticide outlet 2: tank lid11: insecticide outlet 3: fuel cap with gasket 12: hose tank to cock 3: fuel cap with gasket12: hose tank to cock 4: fuel tank 13: hose to direct the air fl ow 4: fuel tank13: hose to direct the air fl ow 5: handle for starter 14: on/off valve 5: handle for starter14: on/off valve 6: throttle valve 15: rigid pipe 6: throttle valve15: rigid pipe 7: fuel valve 16: fl ow regulator 7: fuel valve16: fl ow regulator 8: throttle lever 17: gas restrictor or Venturi 8: throttle lever17: gas restrictor or Venturi 9: hose  9: hose  "},{"text":"Berthoud micron Sprayers nozzle colour flow rate nozzle colour flow rate  Violet 25 Red 90 Violet25Red90 Blue 45 Black 150 Blue45Black150 Yellow 85 Grey 175 Yellow85Grey175 Red 100 Pink 195 Red100Pink195 Green 150   Green150 Black 200   Black200  "},{"text":"table Xviii . Flow rate of two different hand-held sprayers for water-based formulations (after Berthoud and Micron Sprayers).  "},{"text":"flow rate (ml/min) high speed v3m and v3e medium speed v3e only Low speed ve3 only rpm vmd rpm vmd rpm vmd  Weight  65 kg     Weight65 kg power  Voltage: 12 V DC Strength: 8 A maximum    powerVoltage: 12 V DC Strength: 8 A maximum frame  30 and 40 mm box section mild steel Folding mast and support arm. Nylon coated  frame30 and 40 mm box section mild steel Folding mast and support arm. Nylon coated   Formulation tank: 100 l, 5 litres graduations Flushing Formulation tank: 100 l, 5 litres graduations Flushing tanks  tank: 10 litres Moulded metal insert, no straps   tankstank: 10 litres Moulded metal insert, no straps   UV stabilised high density polyethylene  UV stabilised high density polyethylene atomiser speed adjustment Single speed of 7,000 rpm for V3M 3 speeds for V3E (4,500, 6,000 and 7,200 rpm)  atomiser speed adjustmentSingle speed of 7,000 rpm for V3M 3 speeds for V3E (4,500, 6,000 and 7,200 rpm)   V3M: standard on/of pump and atomiser control Fused V3M: standard on/of pump and atomiser control Fused   with Led and light    with Led and light control box  V3E: electronic control.    control boxV3E: electronic control.   Master on/off; 3 atomiser speed settings  Master on/off; 3 atomiser speed settings   10 fl ow control settings. LED lights-fused  10 fl ow control settings. LED lights-fused 0 7,800 - 5,200 - 4,000 - 07,800-5,200-4,000- 200 7,600 50 - - 3,900 90 2007,60050--3,90090 300 7,400 55 5,000 65 3,850 95 3007,400555,000653,85095 500 7,000 60 4,850 75 3,800 105 5007,000604,850753,800105 1,000 6,800 70 4,700 85 3,700 120 1,0006,800704,700853,700120 1,500 6,600 75 4,500 95 3,700 130 1,5006,600754,500953,700130  "},{"text":"table XXi . Droplet size against fl ow rate and rotational speed ofV3E and V3M atomiser(after  Micron Sprayers, 1999).  "},{"text":"table XXii . Flow rate with regards to the restrictor position, with V3M sprayer (after MicronSprayers, 1999). Flow rate will vary with liquid viscosity.  "},{"text":"table XXiii . Flow rate according to the fl ow control position, with V3E sprayer. The test was made with oil (after MicronSprayers, 1999).  "},{"text":"table XXiv . Specifi cations of some airplanes used in pest control(after Castel, 1982). anahuac (mexico)        anahuac (mexico) El Tauro 300 300 1,606 800 - 137 81 152 El Tauro 300300 1,606800-13781152 antonov (poland)        antonov (poland) AN2M 1,000 5,500 1,960 200 200 75 132 AN2M1,000 5,5001,96020020075132 Britten norman (UK)        Britten norman (UK) Islander 600 - 1,000 250 220 70 - Islander600-1,00025022070- cessna (USa)        cessna (USa) Ag Wagon 285 1,497 757 257 183 92 210 Ag Wagon2851,49775725718392210 Ag Truck 285 1,497 1,056 207 166 92 210 Ag Truck2851,4971,05620716692210 Ag Carryall 300 1,514 569 290 180 90 257 Ag Carryall3001,51456929018090257 de havilland (canada)        de havilland (canada) Beaver Turbo DHC2 578 2,313 910 152 225 97 361 Beaver Turbo DHC2578 2,31391015222597361 MKIII        MKIII grumman (USa) Ag Cat Super Ag Cat 450 600 2,041 2,041 980 1,133 228 120 161 177 107 - 329 - grumman (USa) Ag Cat Super Ag Cat450 6002,041 2,041980 1,133228 120161 177107 -329 - pilatus (Switzerland)        pilatus (Switzerland) Turbo PL6 B1-H2 550 2,200 1,176 198 202 112 460 Turbo PL6 B1-H2550 2,2001,176198202112460 piper aircraft (USa) PA 18A PA 25 Pawnee brave PA 36 150 235 300 949 735 1,085 370 600 860 92 400 488 145 160 180 69 90 106 232 350 488 piper aircraft (USa) PA 18A PA 25 Pawnee brave PA 36150 235 300949 735 1,085370 600 86092 400 488145 160 18069 90 106232 350 488 rockwell int. (USa)        rockwell int. (USa) Turbo Trush SR2R 750 1,633 2,086 183 153 106 400 Turbo Trush SR2R7501,6332,086183153106400 Air Tractor AT302T 600 1,474 1,457 238 217 82 606 Air Tractor AT302T6001,4741,45723821782606  "},{"text":" They have a translucid zone visible out of the fuselage. A translucent window before the pilot allows him to follow up the level of liquid in the hopper. helicopter hp persons aboard empty weight (kg) take off weight (kg) cruise speed (km/h) range (km) helicopterhppersons aboardempty weight (kg)take off weight (kg)cruise speed (km/h)range (km) Alouette III 870 550 1 + 6 1230 2200 195 500 Alouette III870 5501 + 612302200195500 Alouette II SA 313 - 1 + 4 1020 1600 175 320 Alouette II SA 313-1 + 410201600175320 Alouette II SA 318 360 1 + 4 1050 1650 175 580 Alouette II SA 3183601 + 410501650175580 Lama SA 315 870 550 1 + 4 1080 1950 180 500 Lama SA 315870 5501 + 410801950180500 Bell 206 Jet Ranger 420 370 1 + 4 720 1450 215 752 Bell 206 Jet Ranger420 3701 + 47201450215752 Bell 47 G2 260 1 + 2 740 1110 120 310 Bell 47 G22601 + 27401110120310 Bell 47 G4 320 1 + 2 840 1335 130 450 Bell 47 G43201 + 28401335130450 Ecureuil 650 1 + 5 1050 1950 220 620 Ecureuil6501 + 510501950220620 Ecureuil 350 B2 742 1 + 5 1134 2500 236 670 Ecureuil 350 B27421 + 511342500236670 Hughes 500 450 1 + 5 700 1360 220 450 Hughes 5004501 + 57001360220450  "},{"text":"Identifi cation manufacturer's reference Orifi ce  O EX 194/O Odd numbers OEX 194/OOdd numbers E EX 194/E Even numbers EEX 194/EEven numbers L EX 194/L 1 to 7 numbers LEX 194/L1 to 7 numbers H EX 194/H 8 to 14 numbers HEX 194/H8 to 14 numbers B EX 194/B None BEX 194/BNone  "},{"text":"the maxi- mum viscosity compatible with the use of micronair is 50 centistokes.   "},{"text":"table XXiX . Recapitulation of the basic parameters of controlled drift spraying.  "},{"text":"table XXXii . Troubleshooting pertaining to hand-held ULV sprayers. Atomiser disc Batteries worn out Replace batteries Atomiser discBatteries worn outReplace batteries does not spin or spins intermittently Batteries not fi tted correctly Atomiser disc rubbing on motor Correct position or replace if necessary Replace disc or motor if does not spin or spins intermittentlyBatteries not fi tted correctly Atomiser disc rubbing on motorCorrect position or replace if necessary Replace disc or motor if  base plate or motor shaft bent necessary base plate or motor shaft bentnecessary  Electrical contacts broken or Replace if necessary Electrical contacts broken orReplace if necessary  corroded  corroded  Electrical terminals and contacts Clean scrupulously Electrical terminals and contactsClean scrupulously  encrusted  encrusted  Motor jammed or wear Give back sprayer to supervisor Motor jammed or wearGive back sprayer to supervisor   or replace motor or replace motor Atomiser disc Batteries are worn out Replace batteries Atomiser discBatteries are worn outReplace batteries spins slowly Atomiser disc rubbing on motor Replace disc or motor if spins slowlyAtomiser disc rubbing on motorReplace disc or motor if  base plate or motor shaft bent necessary base plate or motor shaft bentnecessary  Disc or motor plate encrusted Clean by solvent and a dry Disc or motor plate encrustedClean by solvent and a dry   cloth (follow manufacturer's cloth (follow manufacturer's   instructions) instructions) Insecticide Feed nozzle incorrectly fi tted Refi t properly InsecticideFeed nozzle incorrectly fi ttedRefi t properly does not fl ow   does not fl ow or fl ows Feed nozzle obstructed Unblock and a thin stem and or fl owsFeed nozzle obstructedUnblock and a thin stem and irregularly  soak in soapy water. Never blow irregularlysoak in soapy water. Never blow   in the feed nozzle with mouth in the feed nozzle with mouth  Incorrect position of the spray Adjust spray head position Incorrect position of the sprayAdjust spray head position  head Check that seal inside cap is in headCheck that seal inside cap is in   place and undamaged place and undamaged   Check if bottle is screwed Check if bottle is screwed   correctly or undamaged correctly or undamaged Big drops leak Disc encrusted or damaged Clean disc or change it Big drops leakDisc encrusted or damagedClean disc or change it from the disc Disc not fi xed properly Fit disc properly from the discDisc not fi xed properlyFit disc properly  Feed nozzle incorrectly fi tted Refi t properly Feed nozzle incorrectly fi ttedRefi t properly Liquid leaks Bottle cap not screwed correctly Screw cap properly or change it Liquid leaksBottle cap not screwed correctlyScrew cap properly or change it from the bottle or damaged if necessary from the bottleor damagedif necessary holder   holder  Feed nozzle is incorrectly fi tted Refi t properly Feed nozzle is incorrectly fi ttedRefi t properly  "},{"text":" Be careful! This operation should not be accomplished with the vehicle because, at this scale, the vehicle speedometer is not accurate enough; it would alter the basis of the calibration and thus the results. type of vehicle 1st gear forward speed (km/h) 2nd gear 3rd gear 1st gear 2nd gear type of vehicle1st gearforward speed (km/h) 2nd gear 3rd gear 1st gear2nd gear  + reduction + reduction + reduction   + reduction+ reduction+ reduction Land Rover 110 (diesel) 4.77 7.91 11.39 10.81 14.06 Land Rover 110 (diesel)4.777.9111.3910.8114.06 Mitsubishi L200 (diesel) 4.7 7.12 11.32 7.54 13.74 Mitsubishi L200 (diesel)4.77.1211.327.5413.74 Toyota Land      Toyota Land Cruiser 7.82 13.53  14.06  Cruiser7.8213.5314.06 (gasoline)      (gasoline) Toyota Land Cruiser (diesel) 3.53 6.45 11.8 6.86 12.63 Toyota Land Cruiser (diesel)3.536.4511.86.8612.63  "},{"text":"table XXXiv . Forward speed calibration form for carrier vehicles. Time to cross 500 m and corresponding speed of all terrain vehicle. Vehicule trademark: Type:  Model:  Vehicule trademark:Type:Model:  Calibration distance (D) (km):   Calibration distance (D) (km):  time (sec)   Speed time (sec)Speed gear [min. x 600 = sec] mean time (t) (km/h) [V = D x gear[min. x 600 = sec]mean time (t)(km/h) [V = D x 1st trial 2nd trial 3rd trial (sec) 3 600/t] 1st trial2nd trial3rd trial(sec)3 600/t] 1st gear +     1st gear + reduction     reduction 2nd gear +     2nd gear + reduction     reduction 3rd gear +     3rd gear + reduction     reduction 1st gear     1st gear  "},{"text":" Maximal track spacing against vs wind speed and emission height for spraying with vehicle-mounted sprayer.  time Speed (km/h) time Speed (km/h) timeSpeed (km/h)timeSpeed (km/h)  6 min 00 s 5.00  6 min 00 s5.00  5 min 46 s 5.20 2 min 56 s 10.20 5 min 46 s5.202 min 56 s10.20  5 min 33 s 5.40 2 min 53 s 10.40 5 min 33 s5.402 min 53 s10.40  5 min 21 s 5.60 2 min 50 s 10.60 5 min 21 s5.602 min 50 s10.60  5 min 10 s 5.80 2 min 47 s 10.80 5 min 10 s5.802 min 47 s10.80  5 min 00 s 6.00 2 min 44 s 11.00 5 min 00 s6.002 min 44 s11.00  4 min 50 s 6.20 2 min 41 s 11.20 4 min 50 s6.202 min 41 s11.20  4 min 41 s 6.40 2 min 38 s 11.40 4 min 41 s6.402 min 38 s11.40  4 min 33 s 6.60 2 min 35 s 11.60 4 min 33 s6.602 min 35 s11.60  4 min 25 s 6.80 2 min 33 s 11.80 4 min 25 s6.802 min 33 s11.80  4 min 17 s 7.00 2 min 30 s 12.00 4 min 17 s7.002 min 30 s12.00  4 min 10 s 7.20 2 min 28 s 12.20 4 min 10 s7.202 min 28 s12.20  4 min 03 s 7.40 2 min 25 s 12.40 4 min 03 s7.402 min 25 s12.40  3 min 57 s 7.60 2 min 23 s 12.60 3 min 57 s7.602 min 23 s12.60  3 min 51 s 7.80 2 min 21 s 12.80 3 min 51 s7.802 min 21 s12.80  3 min 45 s 8.00 2 min 18 s 13.00 3 min 45 s8.002 min 18 s13.00  3 min 40 s 8.20 2 min 16 s 13.20 3 min 40 s8.202 min 16 s13.20  3 min 34 s 8.40 2 min 14 s 13.40 3 min 34 s8.402 min 14 s13.40  3 min 29 s 8.60 2 min 12 s 13.60 3 min 29 s8.602 min 12 s13.60  3 min 25 s 8.80 2 min 10 s 13.80 3 min 25 s8.802 min 10 s13.80  3 min 20 s 9.00 2 min 09 s 14.00 3 min 20 s9.002 min 09 s14.00  3 min 16 s 9.20 2 min 07 s 14.20 3 min 16 s9.202 min 07 s14.20  3 min 11 s 9.40 2 min 05 s 14.40 3 min 11 s9.402 min 05 s14.40  3 min 07 s 9.60 2 min 03 s 14.60 3 min 07 s9.602 min 03 s14.60  3 min 04 s 9.80 2 min 02 s 14.80 3 min 04 s9.802 min 02 s14.80  3 min 00 s 10.00 2 min 00 s 15.00 3 min 00 s10.002 min 00 s15.00 128 Locust Control Handbook  128Locust Control Handbook  "},{"text":"table XXXv . Drift of droplets and maximal track spacing to be adopted when spraying with vehicle-mounted sprayers. emission height h (m) Wind speed (m/s) U 40 50 droplet size (microns) 60 70 80 90 100 120 maximal track t (m) spacing emission height h (m)Wind speed (m/s) U4050droplet size (microns) 60 70 80 90 100 120maximal track t (m) spacing  1 42 27 19 14 11 9 7 5 14227191411975  2 85 54 38 28 22 17 14 11 28554382822171411  3 127 82 57 42 33 26 22 17 312782574233262217 2 4 170 110 76 56 44 35 28 22 24170110765644352822  5 213 137 95 71 55 44 34 28 5213137957155443428  6 255 164 114 85 66 53 43 34 62551641148566534334  7 298 199 133 100 76 61 50 39 729819913310076615039  1 64 41 29 21 16 13 11 9 1644129211613119  2 127 82 57 43 33 26 22 17 212782574333262217  3 191 123 86 64 49 39 33 25 3191123866449393325 3 4 255 164 114 84 66 52 43 34 342551641148466524334  5 320 205 145 106 82 66 54 42 532020514510682665442  6 384 246 174 128 98 79 65 51 638424617412898796551  7 448 287 203 149 115 92 76 59 7448287203149115927659  1 85 54 38 28 22 17 14 11 18554382822171411  2 170 110 76 56 44 35 28 22 2170110765644352822  3 255 164 114 85 66 53 43 34 32551641148566534334 4 4 340 219 152 113 87 70 58 45 4434021915211387705845  5 426 274 190 149 109 88 72 56 5426274190149109887256  6 510 329 229 170 131 105 86 68 65103292291701311058668  7 596 384 266 200 152 122 100 78 759638426620015212210078  1 106 68 48 35 27 22 18 14 110668483527221814  2 213 137 95 71 55 44 34 28 2213137957155443428  3 319 205 145 106 82 66 54 42 331920514510682665442 5 4 426 274 190 149 109 88 72 56 54426274190149109887256  5 532 342 238 177 137 110 90 70 55323422381771371109070  6 638 411 286 213 164 132 108 85 663841128621316413210885  7 745 479 333 248 191 154 126 99 774547933324819115412699  1 149 96 67 55 38 31 25 20 114996675538312520  2 298 192 133 99 77 61 50 39 22981921339977615039  3 448 287 203 149 115 92 76 59 3448287203149115927659 7 4 596 384 266 200 152 122 100 78 7459638426620015212210078  5 745 479 333 248 191 154 126 99 574547933324819115412699  6 894 575 400 298 230 184 151 118 6894575400298230184151118  7 1042 671 467 348 268 215 176 138 71042671467348268215176138  1 213 137 95 71 55 44 34 28 1213137957155443428  2 426 274 190 149 109 88 72 56 2426274190149109887256  3 638 411 286 213 164 132 108 85 363841128621316413210885 10 4 851 548 381 284 224 175 144 113 104851548381284224175144113  5 1064 685 485 355 273 219 180 141 51064685485355273219180141  6 1277 822 571 426 328 263 216 169 61277822571426328263216169  7 1489 958 667 496 383 307 251 197 71489958667496383307251197  "},{"text":"table XXXviii . Abacus for the use of Toyota Land Cruiser gasoline equipped with exhaust nozzle sprayer  "},{"text":"table XL . Drift of droplets and track spacing to be adopted for blanket spraying in aerial applications of acridids. emission height h (m) Wind speed (m/s) U 40 50 droplet size (microns) 60 70 80 90 100 120 maximal track t (m) spacing emission height h (m)Wind speed (m/s) U4050droplet size (microns) 60 70 80 90 100 120maximal track t (m) spacing  1 106 68 48 35 27 22 18 14 110668483527221814  2 213 137 94 70 54 44 38 24 2213137947054443824 5 3 4 319 426 205 274 143 188 106 140 82 109 66 88 54 72 42 56 53 4319 426205 274143 188106 14082 10966 8854 7242 56  5 532 411 238 177 136 110 90 70 55324112381771361109070  6 638 432 286 212 164 132 108 84 663843228621216413210884  1 213 137 95 71 54 43 35 28 1213137957154433528  2 426 274 188 140 109 88 72 56 2426274188140109887256 10 3 4 638 851 411 548 286 381 212 283 164 218 132 175 108 143 84 112 103 4638 851411 548286 381212 283164 218132 175108 14384 112  5 1064 685 476 355 273 219 179 140 51064685476355273219179140  6 1277 822 571 425 328 263 216 169 61277822571425328263216169  1 213 137 143 106 82 66 54 42 121313714310682665442  2 638 411 286 212 164 132 108 84 263841128621216413210884 15 3 4 937 1277 616 822 428 571 319 426 246 328 197 263 161 216 126 169 153 4937 1277616 822428 571319 426246 328197 263161 216126 169  5 1595 1027 714 532 410 328 269 211 515951027714532410328269211  6 1915 1233 857 638 492 395 324 254 619151233857638492395324254  1 426 274 190 142 109 87 72 56 1426274190142109877256 20 2 3 851 1277 584 822 381 571 283 425 219 328 175 263 144 216 113 169 202 3851 1277584 822381 571283 425219 328175 263144 216113 169  4 1702 1096 762 567 437 351 288 225 417021096762567437351288225  1 638 411 286 213 164 132 108 84 163841128621316413210884 30 2 1277 822 571 426 328 263 216 169 3021277822571426328263216169  3 1915 1233 857 638 492 395 324 254 319151233857638492395324254 40 1 2 851 1702 548 1096 286 571 213 426 164 328 132 263 108 216 84 169 401 2851 1702548 1096286 571213 426164 328132 263108 21684 169  "}],"sieverID":"46c12d9b-b464-4171-913c-a8bb8494c33e","abstract":"for Agricultural and Rural Cooperation (CTA) was established in 1983 under the Lomé Convention between the ACP (African, Caribbean and Pacific) Group of States and the European Union Member States. Since 2000, it has operated within the framework of the ACP-EU Cotonou Agreement. CTA's tasks are to develop and provide products and services that improve access to information for agricultural and rural development, and to strengthen the capacity of ACP countries to acquire, process, produce and disseminate information in this area.CTA is financed by the European Union."}
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