Protect corn yields with a zero tolerance approach to weed control

August 27, 2018

Reducing the weed seed bank is the first step to weed management plans

RESEARCH TRIANGLE PARK, N.C., Aug. 28, 2018 /PRNewswire/ -- As cousins in the pigweed family, Palmer amaranth and waterhemp are aggressive, invasive weeds and a threat to corn yields throughout the Midwest. Palmer amaranth can produce up to half a million seeds without competitioni. In ideal conditions, a waterhemp plant can produce up to a million seedsii. Mark Waddington, selective corn herbicides product development manager at Bayer, said that if not controlled, these weeds can lead to long term management problems.

"Anything less than 100 percent control of prolific seed producers like Palmer amaranth and waterhemp opens the door to thousands, if not millions, of weeds in future seasons," said Waddington. "As more seeds are added to the weed seed bank, weed control will become increasingly difficult. Additionally, it is vital to eliminate resistant weeds like Palmer amaranth and waterhemp in fields to help prevent the spread of weed resistance."

Waddington noted that Palmer amaranth and waterhemp both produce tiny and easily escapable seeds. They transfer through wind, weather, manure and animals, as well as in machinery. Millions of seeds mean that in just one season, these weeds can develop into a major long-term problem for growers.

Palmer amaranth, which has been documented in 28 states, is the more destructive of the two weeds; it has a reported yield loss in corn of up to 91 percentiii. Waterhemp has spread to 40 states, and a reported corn yield loss of up to 15 percentiv.

"Growers should take a holistic approach to managing Palmer amaranth and waterhemp," said Frank Rittemann, selective corn herbicides product manager at Bayer. "This includes crop rotation, tillage and cover crops, as well as monitoring ditches and borders. Growers should use pre- and post-emergent herbicides with multiple sites of action that are effective on problem weeds like Palmer amaranth and waterhemp."

Rittemann recommends using Corvus® pre-emergence herbicide and DiFlexx® DUO postemergence herbicide for season-long control of Palmer amaranth, waterhemp and other resistant weeds like ragweed or marestail.

"Corvus followed by DiFlexx DUO provides a zero tolerance approach to weed management," said Rittemann. "We recommend tank mixing Corvus with atrazine and DiFlexx DUO with glyphosate. Used together, this recommended zero-tolerance approach combines multiple effective sites of action and six distinct and powerful active ingredients for season-long control and proactive resistance management."

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Work Cited
i Legleiter, Travis and Johnson, Bill. "Palmer Amaranth Biology, Identification, and Management." Purdue Extension.
ii Bradley, K., Smeda, R., Massey, R. "Management of Glyphosate-Resistant Waterhemp in Corn and Soybean." University of Missouri Extension
iii Legleiter, Travis and Johnson, Bill. "Palmer Amaranth Biology, Identification, and Management." Purdue Extension.
iv Nordby, D., Hartzler, B. and Bradley, K. "Biology and Management of Waterhemp." Purdue Extension.