Palmer amaranth, often referred to as pigweed, needs three things to gain a solid foothold in farmers’ fields: heat, water and light. Unfortunately, this hard-to-manage weed has had plenty of all three this year, says Larry Steckel, University of Tennessee Extension weed specialist. Steckel spoke on the topic of managing glyphosate-resistant Palmer amaranth during the fifth annual Corn College near Heyworth, Ill.
"Remember, once glyphosate-resistant Palmer amaranth grows larger than 4" tall, there are no herbicides that will control it in conventional or Roundup Ready soybeans," Steckel says.
He adds that a very high rate of Liberty herbicide (36 oz/acre) can control the weed up to approximately 6" tall but will provide very inconsistent control of Palmer amaranth taller than that.
At this point in the growing season, Steckel says farmers need to begin thinking about which herbicide system they intend to use in 2013: Roundup Ready, LibertyLink or conventional.
"Conventional soybeans are much cheaper but in limited varieties and supply," he says. "Regardless of which system you decide upon, many of the same herbicides will be used, particularly before planting. If you decide on LibertyLink or conventional, be sure to get your seed needs locked in early."
Check out the following video for more information from Steckel on the spread of Palmer amaranth in the Midwest and control steps you can take.
Thank you to the 2012 Corn College sponsors:
Ag Leader, AgriGold, Agrotain, BASF, Chevrolet, ESN/Agrium, Great Plains, NCGA, Novazymes, Precision Planting, SFP, Schaffert, Top Third Marketing, WolfTrax