1/22/2020

Q & A: Herbicide resistance in the upper Midwest

Herbicide-resistant weeds are top threats to corn and soybean yield potential. Jeff Moon, market development specialist with Corteva Agriscience, has insights on the state of resistant weeds and herbicide options. Moon works with retailers and territory managers with Corteva Agriscience in Minnesota and Wisconsin. Read the Q&A below for Moon’s advice to control resistant weeds this season.

  1. What are the top three herbicide-resistant weeds affecting corn and soybean farmers in your area?
    Waterhemp, giant ragweed and lambsquarters, in that order. Waterhemp is in the pigweed family, which has known resistance issues, so it seems to be the focus of conversations right now.

  2. Which herbicide-resistant weeds have most recently shown up?
    The further west you go, kochia becomes an issue. We’re also having discussions about Palmer amaranth moving in and the concerns about that. In the heart of corn country, the herbicide-resistant weeds we mostly see are waterhemp, giant and common ragweed, and lambsquarters.

  3. When new resistance is found in your area, what is the first step to combating it?
    It starts with a discussion between the retailer and farmer. They both pay attention to local conditions, agronomy news and university research. Farmers are on the lookout for new threats and will make an adjustment if needed. Before changing products, they might just tweak their current program to make it better. This means they might change herbicide rates or, if they’re doing one pass, they’ll adjust to a two-pass or change the tank mix.

  4. Which herbicides are particularly effective on these herbicide-resistant species?
    We are fortunate to have several residual and burndown products from Corteva Agriscience that fit the way growers want to farm.

 

If you’re looking for a multiproduct approach in corn, one of the best ways to control resistant weeds is to use SureStart® II herbicide or Resicore® herbicide pre- or postemergence. I’ve seen farmers have success putting Surpass® NXT herbicide or Keystone® NXT herbicide down first and then using SureStart II or Resicore over the top on the second pass to control remaining weeds and add a residual layer. This is a great one-two punch to get corn to canopy.

Talk with your retailer to learn more about corn herbicides from Corteva that can help you control herbicide-resistant weeds.
 

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