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' SPRAY DRIFT MANAGEMENT Avoiding spray drift at the application site is the responsibility of the applicator.The interaction of many equipment-and weather-related fac- tors determine the potential for spray drift.The applicator and grower are responsible for considering all these factors when making decisions. ' The following drift management requirements must be followed to avoid off-target drift movement from aerial applications to agricultural field crops.These requirements do not apply to forestry applications, public health uses or to applications using dry formulations. 1. The distance of the outermost nozzles on the boom must not exceed 3/4 the length of the wingspan or rotor. 2. Nozzles must always point backwards parallel with the airstream and never be pointed downwards more than 45 degrees. ' Where states have more stringent regulations,they must be observed. The applicator must be familiar with and take into account the information covered in the Aerial Drift Reduction Information section below. Aerial Drift Reduction Information ' INFORMATION ON DROPLET SIZE The most effective way to reduce drift potential is to apply large droplets.The best drift management strategy is to apply the largest droplets that provide sufficient coverage and control.Applying larger droplets reduces drift potential, but will not prevent drift if applications are made improperly, or under unfavorable environmental conditions(see"Wind", "Temperature and Humidity", and "Temperature Inversions"). ' CONTROLLING DROPLET SIZE • Volume-Use high flow rate nozzles to apply the highest practical spray volume. Nozzles with higher rated flows produce larger droplets. • Pressure - Do not exceed the nozzle manufacturer's recommended pressures. For many nozzle types lower pressure produces larger droplets.When higher flow rates are needed, use higher flow rate nozzles instead of increasing pressure. ' • Number of Nozzles-Use the minimum number of nozzles that provide uniform coverage. • Nozzle Orientation-Orienting nozzles so that the spray is released parallel to the airstream produces larger droplets than other orienta- tions and is the recommended practice. Significant deflection from horizontal will reduce droplet size and increase drift potential. • Nozzle Type- Use a nozzle type that is designed for the intended application. With most nozzle types, narrower spray angles produce ' larger droplets. Consider using low-drift nozzles. Solid stream nozzles oriented straight back produce the largest droplets and the lowest drift. • Boom Length-For some use patterns, reducing the effective boom length to less than 3/4 of the wingspan or rotor length may further reduce drift without reducing swath width. • Application Height-Applications should not be made at a height greater than 10 feet above the top of the largest plants unless a greater height is required for aircraft safety. Making applications at the lowest height that is safe reduces exposure of droplets to evapo- ration and wind. SWATH ADJUSTMENT ' When applications are made with a crosswind,the swath will be displaced downwind.Therefore,on the up and downwind edges of the field, the applicator must compensate for this displacement by adjusting the path of the aircraft upwind.Swath adjustment distance should increase with increasing drift potential(higher wind, smaller drops, etc.). ' WIND Drift potential is lowest between wind speeds of 2-10 mph. However,many factors,including droplet size and equipment type determine drift potential at any given speed.Application should be avoided below 2 mph due to variable wind direction and high inversion potential. Do not apply by air when wind speed is greater than 8 mph. Do not apply by ground when wind speed is greater than 10 mph. ' Note: Local terrain can influence wind patterns. Every applicator should be familiar with local wind patterns and how they affect spray drift. TEMPERATURE AND HUMIDITY When making applications in low relative humidity,set up equipment to produce larger droplets to compensate for evaporation. Droplet evap- oration is most severe when conditions are both hot and dry. Do not apply when air temperatures exceed 90°F. ' TEMPERATURE INVERSIONS Do not make applications during a temperature inversion because drift potential is high. Temperature inversions restrict vertical air mixing, which causes small suspended droplets to remain in a concentrated cloud.This cloud can move in unpredictable directions due to the light variable winds common during inversions. Temperature inversions are characterized by increasing temperatures with altitude and are com- mon on nights with limited cloud cover and light to no wind. They begin to form as the sun sets and often continue into the morning.Their presence can be indicated by ground fog; however, if fog is not present, inversions can also be identified by the movement of smoke from a ground source or an aircraft smoke generator.Smoke that layers and moves laterally in a concentrated cloud(under low wind conditions)indi- cates an inversion,while smoke that moves upward and rapidly dissipates indicates good vertical air mixing. ' SENSITIVE AREAS The pesticide may only be applied when the potential for drift to adjacent sensitive areas(e.g.,residential areas, bodies of water, known habi- tat for threatened or endangered species, non-target crops) is minimal(e.g.,when wind is blowing away from the sensitive areas). CLEANING SPRAY EQUIPMENT All mixing equipment and air spray equipment should be thoroughly cleaned before and after mixing and applying QUNSTAR@ 4L. 5