Glyphosate-Resistant Pigweed Continues to Menace Mid-South
Pigweed uncontrolled by glyphosate has anchored itself in yet another location – Louisiana. Palmer pigweed was recently confirmed glyphosate resistant in Arkansas. This article explains testing is being conducted at the Syngenta Vero Beach Research Facility in Vero Beach, Fla. to confirm whether or not this unidentified species of pigweed is in fact resistant. This would be the first glyphosate-resistant weed for the state, and fourth state in the Mid-South with glyphosate-resistant pigweed.
Pigweed seeds are small and lightweight. Flooding is one possible explanation for the dramatic spread. Additionally, pigweed is a very diverse plant. In a recent case in Arkansas, one mother glyphosate-resistant plant produced at least 25 offspring, all looking different from one another. With diversity comes more opportunities for mutations to occur, meaning resistance to herbicides can develop more easily.
The simple rule when using glyphosate-tolerant crops is to use a residual herbicide. Rotate chemicals with different modes-of action and use a tankmix when you can. Pay close attention to what fields look like at harvest. This will help determine management decisions for next year. There are no new tools to rely on in the near future, so management of what is already available is critical.