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Arkansas researchers find Palmer Amaranth with glufosinate resistance

A recent study shows some Palmer Amaranth has built up resistance to another chemical mode of action.  Professor Tom Barber is with the University of Arkansas Extension. He says, “We have populations in Arkansas now that we know of or at least five-way resistance. This particular population, we found a couple, actually three fields that were sampled and screened in the greenhouse that are glufosinate resistant.”

Barber tells Brownfield they have a lot of Palmer Amaranth in Arkansas that is still resistant to five modes of action but not yet resistant to glufosinate.

And, he says farmers don’t have many tools left. “The short answer is we’re running out of options. Across the river in Tennessee, there are some populations resistant to dicamba, so we’re concerned that we’re quickly running out of chemical options. There’s no doubt about that.”

Barber says there are still ways farmers can battle the pigweed varieties. “So, a flood can help in a rice rotation. We can use different herbicides in a corn rotation. We can narrow our row spacing at least in soybeans. We can do cover crops, and we know that cover crops that include a high population of cereal rye can greatly reduce the pigweed emergence numbers the next year.”

Barber tells Brownfield early planting helps control weeds, and regardless of which control method is chosen, farmers and crop consultants need to scout often for Palmer Amaranth.