Herbicide-resistant weeds are top threats to corn and soybean yield potential. Jeff Moon, market development specialist with Corteva Agriscience™, Agriculture Division of DowDuPont, recently shared 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.
- 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.
- 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 and soybean country, the herbicide-resistant weeds we mostly see are waterhemp, giant and common ragweed and lambsquarters.
- 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 look-out 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.
- Which herbicides are particularly effective on these herbicide-resistant species?
We are fortunate to have several residual and burndown products from Corteva Agriscience™, Agriculture Division of DowDuPont, that fit the way growers want to farm.
If your customers are using a multi-product 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, then use 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.
In soybeans, it starts with a strong preemerge. Sonic® and Surveil® herbicides are great options to control broadleaf weeds early. In a burndown situation, DuPont™ Enlite® herbicide can burndown emerged weeds and provide residual activity. Another burndown option is Elevore® herbicide, which prevents regrowth of many resistant weeds, including marestail. Elevore has a low use rate and fits well in reduced or no-till systems.
Talk with your local territory manager from Corteva Agriscience or go to Corteva.US to learn more about corn and soybean herbicides that can help your customers control herbicide-resistant weeds.