Waterhemp and Palmer amaranth look similar, but waterhemp leaves are generally longer and more lance-shaped than other pigweeds.
Editor's Note: This article is provided by Corteva Agriscience™, Agriculture Division of DowDuPont.
(July 19, 2018) - While there are dozens of common weeds that threaten yield each season, many Midwest farmers who grow corn or soybeans are facing off with waterhemp now.
This demanding weed is leading the conversation and building strength against herbicides halfway through 2018. It’s crucial to scout diligently, implement a diverse action plan and use a program herbicide approach with multiple modes of action to combat increasingly resistant waterhemp and other common broadleaf weeds.
“New cases of resistant waterhemp are daunting to those of us in the ag industry because it threatens the already-delicate ROI ratio,” says Dave Roome, customer technical specialist, Corteva Agriscience™, Agriculture Division of DowDuPont. “But waterhemp can grow stronger each year. We have to stay aggressive at reducing the waterhemp seedbank to protect fall yield and get a head start on next season.”
For instance, the recent discovery of six-way resistant waterhemp in Missouri is a major threat to future corn and soybean yield. In the past 25 years, waterhemp has developed documented resistance to six classes of herbicides.1 Many fields across the Corn Belt also house waterhemp that is resistant to two or more modes of action, which requires farmers to evaluate their control program and incorporate additional, or different, herbicides.
“Waterhemp in my area has a really bad resistance problem with glyphosate, which is one reason we’re using SureStart II,” says Missouri farmer Jimmy Daniels. “For corn, we use a two-pass program with SureStart II as our main first pass with a little atrazine. Then, we’ll come back with a second pass of something other than glyphosate to try to prevent resistance. To have a clean field at the end of the year is a great thing.”
Many farmers are improving yield potential and managing the waterhemp seedbank by using a mix of regional-specific best practices and a program herbicide approach throughout the growing season.
Roome shares five tips to help farmers manage waterhemp for the remainder of this season and to limit additional resistance development:
1Heap, I. 2018. The International Survey of Herbicide Resistant Weeds. www.weedscience.org
Corteva Agriscience™, Agriculture Division of DowDuPont (NYSE: DWDP), is intended to become an independent, publicly traded company when the previously announced spinoff is complete by June 2019. The division combines the strengths of DuPont Pioneer, DuPont Crop Protection and Dow AgroSciences. Corteva Agriscience™ provides growers around the world with the most complete portfolio in the industry — including some of the most recognized brands in agriculture: Pioneer®, Encirca®, the newly launched Brevant™ Seeds, as well as award-winning Crop Protection products — while bringing new products to market through our solid pipeline of active chemistry and technologies. More information can be found at www.corteva.com. Follow Corteva Agriscience™, Agriculture Division of DowDuPont, on Facebook, Instagram, LinkedIn, Twitter and YouTube.