Know Where NOT to Spray New Dicamba or 2-4-D Because Eyes Are Watching

By Brad Haire, Southeast Farm Press

Gears are in motion for Louisiana cotton and soybean growers to legally apply auxin herbicides in-season to new seed traits tolerant to them. Each label comes with major restrictions, and every detail should be followed. But it really boils down to a simple philosophy: Know where NOT to spray them. People will be watching.

Auxin herbicides expected to be cleared at the federal and state level for legal in-season use in the 2017 cropping season on resistant seed are Monsanto’s Xtendimax with its new dicamba formulation, BASF’s new dicamba formulation sold as Engenia and Dow AgroSciences’ Enlist Duo, which includes its new 2,4-D formulation.

With the corresponding resistant seed technologies for dicamba or 2,4-D systems available for cotton and soybeans, coupled with the legal clearance to use the herbicides, the stage is set for “significant adaption across the region,” which will be done to manage hard-to-control weeds such as Palmer amaranth, morning glory and to a certain extent tropical spiderwort , said Stanley Culpepper, University of Georgia Extension weed specialist.

In research-grade Palmer amaranth populations, the new technologies do offer slightly more flexibility and improved control over our standard practices with a few dollars less in hand weeding costs at seasons end,” Culpepper said. “It is critically important we have standard programs equally effective, allowing grower’s options. For growers who are able to be timely and aggressive, they are already achieving effective control with standard programs that offer lower off-target drift risks.”

The new auxins are formulated, and their labels written, to reduce the risk of off-target, drift-related crop damage.

Speaking Jan. 6 at the Southeast Regional Fruit and Vegetable Growers Conference, Rick Keigwin, deputy director of programs for EPA’s Pesticide Program office, reminded growers the dicamba registrations have two important time restrictions:

1) Both Monsanto’s and BASF’s registrations automatically expire in November 2018 unless EPA takes action to renew them.

“And what we’re going to be looking at over the next two years is, ‘Are the off-sight drift incidents continuing? To what degree are they continuing? Are they getting worse or are they getting better? Is the magnitude increasing?’” Keigwin said. “And if we determine that that frequency of drift events is unacceptable, they (the registrations) go away.”

2) If the registrations for new dicamba formulation are renewed in November 2018, they will automatically expire three years later. At that time, EPA again will look at drift incidents and also at where things stand with resistance issues. The registrations go away if things are not acceptable.

The bottom line: If EPA doesn’t take action on either deadline for the dicamba registrations, the registrations go away. “So, we all have to be partners to make sure these products are used the right way so that we don’t have the types of things that happened in the Mid-South,” Keigwin said.

Dow’s Enlist Duo 2,4-D formulation will have a five-year term of registration. “It’s five years for Enlist because we haven’t had the drift events like we had for dicamba, and that five years is primarily focused on resistance management,” Keigwin said.