By Emily Unglesbee
DTN Staff Reporter
ROCKVILLE, Md. (DTN) — University of Tennessee weed scientist Larry Steckel has spent the past two months coaxing Palmer amaranth weeds to grow from seed collected in 2019 — so he could try to kill them.
But after a labeled rate of the dicamba herbicide XtendiMax on two-inch tall weeds, in the well-controlled environment of a greenhouse, a lot of that pigweed did not die.
This week, Steckel made a series of grim phone calls he had been bracing for all winter.
?I called the farmers and retailers who found some of these and I told them — dicamba isn’t going to control Palmer amaranth in these fields anymore,? he said. ?They were not surprised at all.?
His colleague, University of Arkansas weed scientist Jason Norsworthy has found the same thing in his greenhouses with samples of Palmer amaranth from Tennessee, which saw widespread reports of dicamba performance failures in 2019.
