News

Dicamba resistant Palmer amaranth rising concern

A University of Tennessee Extension weed scientist says they’ve confirmed dicamba-resistant Palmer amaranth in Tennessee.

Larry Steckel says the dicamba-resistance issue is still categorized as low. “It’s certainly not on every acre, it’s just getting started in some fields,” he says.  “

Steckel says it has a rating of 2.5, which indicates weeds can survive up to 2.5 times the labeled dicamba use rates. 

But, he tells Brownfield it is concerning because the number of tools available to farmers to control weeds is dwindling.  “Palmer amaranth we’re to the raggedy edge now to haven an effective herbicide that’s going to manage it,” he says.  “To me, going forward, we have to steward these herbicides we have left to get some shelf life on them until we get something new.  Because we’re going to need something sooner rather than later now.”

Steckel says with increasing resistance concerns, farmers are going to have to look beyond the herbicide for more solutions.  “Things we had to do twenty years ago,” he says.  “Narrow row widths would be one, cover crops in places, tillage where appropriate would be another good avenue.  Maybe getting the cultivators back out or hoe it, if you’ve got a spot of pigweed that’s gotten through dicamba.  Just go out there and yank it.”

This isn’t the first reported case of dicamba-resistant Palmer amaranth, in 2019 Kansas State University reported resistance issues in one of its long-term conservation tillage research plots. 

AUDIO: Larry Steckel, University of Tennessee Extension