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brad-haire-pigweed-cotton-middle-GA-a.JPG Brad Haire

3 ways to handle large pigweed in cotton after EPA dicamba decision

How to use available dicamba for large pigweed control in tolerant cotton following the EPA dicamba decision.

In a decision June 8, the EPA said if you didn’t own approved dicamba products labeled for tolerant cotton or soybeans on June 3, you can’t spray it. If you did own approved dicamba, there is time, but you'll need to use it wisely to handle cotton weeds.

In the decision EPA, in response to a court order to halt the sale, distribution and use of existing stocks of XtendiMax with vapor grip technology, Engenia and FeXapan, said:

  • Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
  • Growers and commercial applicators may use existing stocks that were in their possession on June 3, the effective date of the Court decision. Such use must be consistent with the product’s previously approved label and may not continue after July 31.

The court decision means cotton growers in Georgia who planted dicamba-tolerant varieties, and most do in Georgia, and growers in other regions, will have to pivot from what might have been their planned weed control management program.

June 8, University of Georgia Extension weed specialist Stanley Culpepper provided three ways growers can use to move forward, based on what is known now.

First and foremost, he said, "Use only labeled products and follow all labeled directions and restrictions."

Scenario One 

For Large pigweed with enough in-crop dicamba for two applications, Culpepper recommends growers 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

For 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

For large pigweed with no dicamba available, sequential Liberty applications will be the best approach, he said, 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 of this system," he said

The Tavium, a dicamba product, registration was not revoked and not, as of now, affected by the court decision.

 He added that Georgia growers, and others, have worked hard to wisely steward each pesticide they use, including dicamba, and should take pride in that. 

"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," he said.

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