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GCC: Cotton Growers Be Wary of Defoliation Drift

Clint Thompson Cotton, Georgia, Georgia Cotton Commission

UGA Extension photo

By Clint Thompson

The Georgia Cotton Commission (GCC) and University of Georgia (UGA) Extension Cotton Team remind growers about the importance of on-target defoliation applications.

Defoliation is the process by which the plant’s leaves must be removed before the cotton can be harvested. This helps speed up the plant’s maturity. Producers make a chemical application and, approximately two weeks later, the crop is ready for harvest.

But if applications are not made on-target, they can be detrimental to nearby crops, says Camp Hand, UGA Extension cotton agronomist.

“That’s something that we need to keep in mind when we’re defoliating this crop,” Hand said. “It’s just being aware of what’s around you whenever you’re making the decision to apply defoliants. Remember the lessons that (Stanley) Culpepper has taught over the past five or six years in those Using Pesticides Wisely Trainings so that we make an on-target defoliant application and reduce the likelihood of drift onto other crops or sensitive areas.”

Georgia producers and their applicators have reduced pesticide drift complaints to UGA Extension by more than 78% since 2014, according to the UGA Extension Cotton Team.

Cotton growers should be wary of various factors if they want that trend to continue.

Drift Factors

The first is to be aware of what is around your fields, such as other crops or neighboring areas. This information can influence a grower’s defoliation decisions, such as when to make an application.

Another is to consider wind speed and direction, which are the two most crucial weather factors influencing drift. Boom height can help reduce spray drift by improving the on-target application. The ideal boom height for ground applications is 24 inches above the plant.

Finally, nozzle type influences the droplet size, which can affect the likelihood of those spray droplets to drift. Smaller droplets remain in the air longer making them vulnerable to move off-target. Effective defoliation can occur with larger droplets, but sprayer output must be in the 15 to 20 GPA (gallons per acre) range.