Karen McMahon

March 5, 2012

2 Min Read

Weed resistance issues were top of mind for many farmers attending the 2012 Commodity Classic held last week in Nashville, Tenn. The media heard plenty about it at a couple pre-conference events.

University of Tennessee’s Larry Steckel spoke to media at a Bayer CropScience event about the glyphosate-resistant weed problems in his area.

“On June 21, 2011, I got a lot of calls that day – 80,” reported Steckel. “Most of the calls were about resistant Palmer pigweed and that’s when it dawned on me just how big of an issue this has become.”

He said growers can manage resistant Palmer pigweed if it is sprayed at 2 in. in height. But just 24 hours later when pigweed is 4 in. tall, glyphosate will control only 75% of the weed population. With only 75% control, farmers will not be able to combine the fields.

Later, a farmer at the event said he has heard of landlords losing their renters because of severe weed resistance in the fields. Land also has been sold at a discounted price if there are heavy populations of resistant pigweed on it.

Multiple resistance

If growers from the northern states think they are safe from the weed resistance issues, they need to think again. Jeff Stachler, extension weed specialist in Minnesota and North Dakota, has documented a serious spread of resistant weeds through these northern growing areas. Speaking at a BASF media event, he said some hot spots have resistant weeds in 75 to 90% of the fields. Resistant weeds include common ragweed, giant ragweed and waterhemp.

“We certainly had a big issue in 2011,” Stachler reported. “But that’s nothing. The real game changer is multiple resistance, which is resistance to more than just one mode-of-action herbicide.”

In fact, he says they may have identified ragweed and waterhemp with three-way resistance in Minnesota and North Dakota. The resistance is to glyphosate, ALS inhibiting and PPO inhibitor herbicides.

  

About the Author(s)

Karen McMahon

Karen McMahon has been a well-respected and award-winning agricultural journalist for more than three decades. In 2000, she served as president of the American Agricultural Editors' Association (AAEA), a group of more than 400 professional farm writers. She also is active in the Agricultural Media Summit (AMS) and served as chairman in 2001 and chair of the sponsorship committee for several years. She has attained the top Master Writer Award level from AAEA and won various writing awards from the Am. Society of Business Publication Editors and Minnesota Monthly Publications Association.

Karen joined Farm Industry News as senior editor in 1998 and was named editor two years later. Prior to that, she was managing editor for five years of another Penton publication, National Hog Farmer. She grew up on a diversified crop and livestock farm near LeMars, IA, and earned her degree in journalism from South Dakota State University. Since then, Karen has worked in agricultural communications.

Her experience on magazines and organizations includes work on Hog Farm Management, the National Pork Producers Council, and Hogs Today/Farm Journal.

Karen may be reached at 9520851-4680

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