Penn State Extension has provided helpful management tips to keep your herbicide applications on-target and a farmer or custom applicator out of hot water from drift.
Aside from the variable climatic conditions this spring, there have been many days with windy conditions. Despite other factors being adequate for spraying, the winds have not been so ideal. Keep in mind the objectives of any spray application are to balance productivity, efficacy, and prevent off-site movement of pesticides. In some situations, this can be easier said than done. Below are several things to consider to help reduce particle (not necessarily, vapor) spray drift.
Not spraying is the best option if there are questions about keeping material on target, but there are things that can be done to mitigate off target potential. [Some of these can negatively affect efficacy depending on the product being applied and must be considered based on the product label directions.]
- Spray at low wind velocities (<10 mph); in general, winds are less early in the morning or late in the evening.
- Reduce spraying pressures; lower pressures allow for larger droplet sizes.
- Increase carrier volumes/application rates; if possible use 20 gallons or more/acre instead of 10 gallons or less/acre.
- Select the proper nozzles with coarse spray droplets; there are several companies that manufacture nozzles that are designed to reduce drift; some examples include: TeeJet AI, AIXR, and TTI; Greenleaf TurboDrop XL; Hypro Ultra Low Drift, among others.
- Use lower spray boom heights; make sure to use nozzles that have 110 degree or more spray angle which allows the boom to be lowered more than nozzles with lesser angles, but ensure spray pattern and proper overlap is maintained.
- Reduce sprayer ground speed (<10 mph); faster speeds cause more boom bounce and spray vortex to occur sending spray droplets higher in the air.
- Use drift retardants; there are many good products on the market for this purpose
- Spray when wind direction is away from sensitive crops, homes, etc.
- Invest in “high-tech” sprayers (e.g., pulse modulation); some of the new sprayers use a pulsing system to assist in better application and drift reduction.