Pesticide Drift & Prevention
1) Select a nozzle that produces coarser (larger) droplets
Use nozzles that provide as coarse (large) droplet as practical to provide necessary coverage. Some labels may require specific droplet size for there use. Nozzle selection guides should give you a listing of droplet size provided by each nozzle. New air induction nozzles help produce larger droplets.
2) Use lower pressure on the sprayer and larger nozzles when possible
Higher pressures generate many more small droplets (less than 100 microns). Under most conditions, do not exceed 40 to 45 psi. Use larger nozzles to increase flow rate instead of higher pressure. Larger nozzles allow more volume (GPA) at lower pressures.
3) Lower boom height
Wind speed increases with height. If boom height is a few inches lower, off-target drift is reduced. Keep boom as close as possible to the crop being sprayed.
4) Spray when wind speeds are low to avoid off target movement.
More spray will move off-target as wind increases. Some labels may specify specific wind speeds to make an application. Check wind speed with a hand held anemometer or the mesonet system before spraying.
5) Spray when wind is moving away from sensitive crops
Leave a buffer zone 50 to 100 feet in width (or larger if needed) if sensitive plants are downwind. Spray the buffer zone when the wind changes direction away from the sensitive crop.
6) Do not spray when the air is very calm
Calm air, or an inversion, reduces air mixing, which means spray can move slowly downwind. Inversions generally occur in early morning or near bodies of water.
7) Avoid high volatile formulations
Avoid ester formulations of certain types of herbicides which can easily volatize in warm temperatures (above 80 F). Amine formulations are very unlikely to volatize but can still cause particle drift.
8) Check ODAFF’s pesticide sensitive viewer for pesticide sensitive crops
Use this Oklahoma Department of Agriculture, Food and Forestry tool to be aware of pesticide sensitive crops near where you will be spraying. Take appropriate measures to protect these crops this may even mean delaying the application. Be aware of surrounding areas when making applications. The listing can be found at http://maps.oda.state.ok.us/pslvags/
9) Follow label recommendations to avoid drift with pesticides.
Labels may have specific requirements or directions for use to avoid drift of those products.
10) Select the time when drift is less likely to occur.
Certain time periods may be best for applications. On many occasions applications may have to be delayed days or weeks for favorable conditions.