A federal agency gave farmers and agricultural retailers the go ahead to continue use of three dicamba product stripped of their registrations.
The clock is ticking, however, as such products must be applied by July 31, 2020. Additional conditions further complicate the situation. Therefore, we will assess other control methods for herbicide-resistant weeds, such as waterhemp.
The Environmental Protection Agency (EPA) on Monday issued a cancellation order, in response to the U.S. Court of Appeals for the Ninth Circuit’s decision to vacate the registrations of three dicamba products: Engenia, FeXapan, XtendiMax. The order states:
- ?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, 2020, 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, 2020.?
Meaghan Anderson, Iowa State University Extension & Outreach field agronomist in central Iowa, offers alternatives for growers, who did not purchase these products before June 3. She notes, “Unfortunately, there are not a lot of great options available for fighting herbicide-resistant waterhemp.” Farmers are limited to: Group 2 (ALS inhibitors), Group 9 (glyphosate), and Group 14 (PPO inhibitors) herbicides.
?And knowing what we know about the waterhemp populations we have in Iowa and across the Midwest, those Group 2 products are not going to do much of anything. We expect that more than 90-percent of our populations in Iowa are resistant to Group 2 products. That leaves us with Group 9 (glyphosate) and products (with) fomesafen, lactofen, or acifluorfen – Flexstar, Cobra, or UltraBlazer. Unfortunately, we have high levels of resistance to those products as well,? Anderson said.
Anderson suggests, “Group 14 herbicides are going to be the best bet, as far as resistance goes.” Such herbicides require extra caution, and farmers should review previous uses of Group 2, 9, and 14 herbicide groups before making a product selection.
?The caution, of course, with Group 14 products is that they?re contact herbicides. They can be effective, but need to be sprayed on small waterhemp,? Anderson said. ?Most of them are going to have restrictions of two- to three-inch waterhemp. Historical use of glyphosate has been on much larger waterhemp plants, so that?s something we need to keep in mind.?
