2021-03-08-minutes-public-works-study-session

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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 factors determines the potential for spray drift. The applicator is responsible for considering all these factors when making decisions. The following drift management requirements must be followed to limit off -target drift movement from aerial applications: Aerial Application: • Aerial applicators must use a minimum finished spray volume of 15 gallons per acre. • Drift potential is lowest between wind speeds of 2 to 10 mph. Do not apply below 2 mph due to variable wind direction and high potential for temperature inversion. Do not apply in wind speeds greater than 10 mph. • To minimize spray drift from aerial application, apply with a nozzle class that ensures coarse or coarser spray (according to ASABE S572) at spray boom pressure no greater than 30 psi. • The distance of the outer most operating nozzles on the boom must not exceed 70% of wingspan or 80% of rotor diameter. • Nozzles must always point backward parallel with the air stream and never be pointed downwards more than 45 degrees. • Do not apply under conditions of a low-level air temperature inversion. • The maximum release height must be 10 feet from the top of the weed canopy, unless a greater application height is required for pilot safety. Evaluate spray pattern and droplet size distribution by applying sprays containing a water-soluble dye marker or appropriate drift control agents over a paper tape (adding machine tape). Mechanical flagging devices may also be used. Do not apply under conditions of a low-level air temperature inversion. A temperature inversion is characterized by little or no wind and lower air temperature near the ground than at higher levels. The behavior of smoke generated by an aircraft -mounted device or continuous smoke column released at or near site of application will indicate the direction and velocity of air movement. A temperature inversion is indicated by layering of smoke at some level above the ground and little or no lateral movement. Ground Application • Ground applicators must use a minimum finished spray volume of 10 gallons per acre. • To minimize spray drift from ground application, apply with a nozzle class that ensures coarse or coarser spray (according to ASABE S572). • For boom spraying, the maximum release height is 36 inches from the soil for ground applications. • Where states have more stringent regulations, they must be observed. The applicator should be familiar with, and take into account the information covered in the following Aerial Drift Reduction Advisory (this information is advisory in nature and does not supersede mandatory label requirements.) Aerial Drift Reduction Advisory 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 specified 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 air stream produces larger droplets than other orientations. 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: To further reduce drift without reducing swath width, boom must not exceed 70% of wingspan or 80% of rotor diameter. Application Height: Do not make applications 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 evaporation 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 to 10 mph. However, many factors, including droplet size and equipment type, determine drift potential at any given speed. Do not make applications below 2 mph due to variable wind direction and high inversion potential. Do not apply in wind speeds greater than 10 mph. 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 evaporation is most severe when conditions are both hot and dry. Temperature Inversions: Do not apply during a local, low level 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 attitude and are common 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 the smoke from a ground source or an aircraft smoke generator. Smoke that layers and moves laterally in a concentrated cloud (under low wind conditions) indicates an inversion, while smoke that moves upward and rapidly dissipates indicates good vertical air mixing. USE DIRECTIONS ProcellaCOR EC performance and selectivity may depend on dosage, time of year, stage of growth, method of application, and water movement. Aquatic Plants Controlled: In -Water Application Table 3 lists the expected susceptible species under favorable treatment conditions for aquatic plant control. Use of lower rates will increase selectivity on some species listed. Consultation with SePRO Corporation is recommended before applying PmcellaCOR EC to detemtine best in -water treatment protocols for given target vegetation. TABLE 3. Vascular aquatic plant control with in -water application Vascular Aquatic Plants Controlled: In -Water Application Common name Scientific name Floating Plants Mosquito fernAzolla spp. Water hyacinth Eichhomia crassipes Emersed Plants Alli atorweed Altemanthers philoxercides American lotus Nelumbo lutea Floating heart Wrnphoides spp. Water perm ort H drocofyle umbellate Water primmse Ludwi is sop. Watershield Brasenia schrebed Submersed Plants Baco a Baco a spit. Coontail' Cerato h Plum demersum H drilla' H drilla verticillata Parrotfeather Mynciphyllum a uaticum Water chestnut Irapa spp. Watermiffoil, Eurasian M doph llum spicatum Watermiffoil,Hbri -Eurasian Mydophllum spicatum X M. spp. Watermiffoil, Variable M no h Ilum heteroph lura Higher -rate applications within the specified range may be required to control less -sensitive weeds. Aauatic Plants Controlled: Foliar Application Table 4lists the expected susceptible species using labeled foliar rates (5.0-10.0 PDU per acre) under favorable treatment conditions for aquatic plant control. Use higher rates in the rate range on more established, dense vegetation. Consultation with SePRO Corporation is recommended before applying ProcellaCOR EC to determine best foliar treatment protocols for given target vegetation.