Ag News

UGA weed science experts weigh effects of dicamba ruling

In the wake of the 9th Circuit Court of Appeals June 3 ruling cancelling the registration of dicamba weed control chemicals, farmers are left seeking alternatives.

UGA weed science experts Stanley Culpepper and Eric Prostko provided analysis of the effects the court decision will have and what farmers can do to mitigate the anticipated crop losses that will result from dicamba being taken out of use.

“The dicamba decision impacts nearly every farmer in the state,” Culpepper said. “In Georgia, we have all worked so hard to steward every pesticide and we should collectively be proud. However, this is a wakeup call in several ways. First, we must work together even harder generating sound science to preempt this type of situation in the future. Second, for those few growers who have downplayed the importance of using all pesticides wisely, what a wakeup call.”

In a blog post Culpepper laid out three scenarios, responses and timelines farmers could follow in response to the court ruling and subsequent EPA cancellation, emphasizing that farmers should use only labeled products and follow all labeled directions and restrictions.

Culpepper’s suggestions:

 • Scenario One:  Large pigweed with enough in-crop dicamba for two applications:  Spray labeled Roundup + dicamba immediately, wait 7 to 10 days and then make a second application; 12 days later run the layby rig with either 1) Direx + MSMA + Crop Oil if grasses are not up or 2) Roundup + Direx if grasses are up (add Envoke with layby if morningglory or nutsedge is a problem).

• Scenario Two:  Large pigweed with enough in-crop dicamba for one application:  Spray labeled Roundup + dicamba immediately, wait 7 to 10 days and then make a Liberty tank mix application; 12 days later run the layby rig with either 1) Direx + MSMA + Crop Oil if grasses are not up or 2) Roundup + Direx if grasses are up (add Envoke with layby if morningglory or nutsedge is a problem).

• Scenario Three: Large pigweed with no dicamba available. Sequential Liberty applications will be best approach although less effective than either dicamba system above. We were able to obtain a new state label for Liberty shortening intervals between sequential applications which will improve control.

Culpepper said Tavium registration was not affected by the court ruling.

Culpepper’s blog post can be found on Cottonfarming.com at https://www.cottonfarming.com/production-2/ugas-stanley-culpepper-offers-thoughts-on-dicamba/.

Prostko estimated that 75% of the soybeans planted in Georgia are dicamba tolerant.

“Growers do not have a choice in many cases,” Prostko told GFB media. “Unlike dicamba-tolerant cotton, current dicamba-tolerant soybeans are not tolerant to Liberty (glufosinate) so this herbicide cannot be used on Xtend soybeans.”

Prostko’s recommendation:

If Xtend soybeans are already planted and up, and growers cannot apply dicamba, the next best POST option would be Roundup + Reflex.  In my opinion, both before and after the release of Xtend soybeans, Georgia soybean growers had other herbicide options that did not have to include dicamba.