Glyphosate-resistant Palmer amaranth weed present in Kansas?
So, it appears that glyphosate-resistant Palmer amaranth may now be present in Kansas, he said.
Palmer amaranth seed was collected from additional fields this past fall and is now being evaluated in a K-State greenhouse.
“Preliminary observations suggest that we are seeing similar survival after glyphosate treatments from Palmer amaranth collected from fields south of Great Bend, along with additional populations collected south of Wichita,” Peterson said. “Research on inheritance and the mechanism of resistance will need to be conducted to further characterize and confirm glyphosate resistance in these populations.”
Confirming herbicide resistance is a long and detailed process, he added.
“Regardless of whether glyphosate-resistant Palmer amaranth is now present in any given area in Kansas, there is a good chance it will develop at some point based upon what has happened in the Southeast U.S., especially if growers rely heavily on glyphosate for weed control,” Peterson said.
“Palmer amaranth is an extremely competitive weed, and the development of glyphosate resistance means it will require an effective integrated weed management program to achieve acceptable control,” he said. “Continuing to rely only on glyphosate for weed control will only speed up the development of glyphosate-resistant weeds and diminish its effectiveness.”
He said that the use of residual herbicides with different modes of action throughout the cropping system will help to manage existing glyphosate-resistant weeds and slow the development of new glyphosate-resistant weed populations.