Weed Control Without Enlist

ROCKVILLE, Md. (DTN) -- Some growers have been forced back to the drawing board for their 2022 weed control options after the new EPA labels for Enlist herbicides banned their use in dozens of counties across the country, due to endangered species concerns.

The news of these spotty herbicide prohibitions took the entire industry off guard, from farmers to seed dealers and even the herbicides' registrant, Corteva Agriscience, which has vowed to work to get these counties back on the label. See more here: https://www.dtnpf.com/….

In the meantime, what is an Enlist grower in these counties to do? Weed scientists from Arkansas, Ohio and Missouri are helping farmers sort through their limited set of options. Essentially, growers can stay the course, keep their Enlist seed and focus on keeping fields clean early to limit pressure on their now-limited postemergence options. Or, if growers decide they must have another postemergence herbicide option, they can try to swap out their Enlist seeds for the Xtend platform -- which comes with its own host of label restrictions and endangered species rules.

So which course is better for you? These four questions can help you make that decision.

WHAT HERBICIDES CAN I GET?

The first question growers holding Enlist seed in these affected counties must answer is whether they have access to glufosinate (Liberty) and glyphosate, now the only legal post application options in their Enlist fields.

Growers were already facing shortages of both these active ingredients and ensuing price spikes, farmers and weed scientists told DTN. University of Arkansas weed scientist Tommy Butts said he has heard of prices for glyphosate soaring toward $60 per gallon, with glufosinate costs pushing $120 per gallon.

Growers might be able to add a different grass-focused herbicide, such as clethodim, to their post application if glyphosate isn't available. But access to glufosinate will be key, Ohio State University weed scientist Mark Loux noted. "If you can't get that, then really what you have is Roundup Ready beans on your hand," he said.

If you do have access to glufosinate, make sure you know how to apply it effectively, as the herbicide needs specific temperature, humidity, nozzle and water carrying parameters to work best. See more here: https://www.dtnpf.com/….

HOW DOES MY PREEMERGENCE PROGRAM LOOK?

Clean fields heading into the summer will be more important than ever for growers facing limited postemergence options, Butts noted.

In addition to a preemergence application with multiple modes of action, he recommends overlapping residuals two to three weeks after it, to make sure fields are clean as the crop gets started.

If possible, planting earlier and planting narrow rows can also help a soybean crop canopy earlier and crowd out emerging weeds, Butts added. "Pigweeds are late germinators," he explained. "So, anything you can do to get that crop producing more biomass before they germinate will help."

WHAT KIND OF HERBICIDE-RESISTANT WEEDS DO I FACE?

Growers need to know the herbicide-resistant weed spectrum they are facing. Glyphosate resistance is common in many broadleaf weeds, and glyphosate-resistant grasses are starting to cause problems in some Southern states as well.

Most recently, some populations of Palmer amaranth and waterhemp are pushing back against dicamba, 2,4-D and even glufosinate. See more here: https://www.dtnpf.com/… and here: https://www.dtnpf.com/….

Growers who are battling PPO-resistant weeds in counties where Enlist herbicides are banned are in especially tough shape, Loux and Butts noted. They will not be able to benefit from adding a PPO-inhibitor such as FlexStar to a postemergence application, which can help tackle tough-to-kill pigweeds such as Palmer amaranth and waterhemp.

"To me, if you know of, or have concerns about, PPO-resistant pigweeds, I would consider switching to Xtend," said Butts. "Because you won't have FlexStar as an option, Liberty is in short supply and all our pigweed is glyphosate-resistant."

CAN I SPRAY DICAMBA IF I SWITCH TO XTEND?

Switching to the Xtend weed control platform can open up another postemergence application option: dicamba.

However, the current labels for over-the-top dicamba herbicides contain many restrictions, including large buffers for counties with endangered species and national cutoff dates of June 30 for soybeans and July 30 for cotton. Read them carefully to make sure they fit your operation: https://www.dtnpf.com/….

If you use commercial applicators, make sure they are on board to apply dicamba, as well, Loux added. Some applicator networks in Ohio will no longer apply over-the-top dicamba, due to volatility and drift concerns, he explained.

Finally, keep an eye on a lawsuit moving through a federal district court in Arizona, where environmental groups have asked a judge to vacate the registrations of XtendiMax, Engenia and Tavium, based on the EPA's own documentation of dicamba injury last year. See more here: https://www.dtnpf.com/….

See more from Loux here on Ohio farmers' options: https://agcrops.osu.edu/….

See Butts' article on this topic for Arkansas farmers here: https://arkansascrops.uada.edu/….

See more recommendations from University of Missouri weed scientists here: https://ipm.missouri.edu/….

Emily Unglesbee can be reached at Emily.unglesbee@dtn.com

Follow her on Twitter @Emily_Unglesbee

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