A combination of weather, changing tillage practices and herbicide resistance is creating trouble for farmers across the Southwest this summer. From South Texas, into the Texas High Plains and all the way into Kansas, weeds are proving difficult to manage.

“Weeds in cotton are all over the board,” says Kerry Siders, Texas AgriLife Extension integrated pest management specialist for Hockley and Cochran Counties, up in the Panhandle.

“We definitely have resistant pigweed,” Siders adds. “In fact, we have resistant pigweed in dryland acres where the Roundup Flex system was never used.”

He says some producers learned early on that Roundup would no longer be sufficient to control pigweed (Palmer amaranth). “These producers began using other herbicides such as the pre-plant incorporated yellow herbicides (trifluralin and pendimethalin) or the at-planting white herbicides (direx, Caparol, etc.), as well as other residual herbicides as Staple, Dual, etc.” 

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Siders says weed control is always a fluid situation and always some growers who will hesitate to change their programs. “With any pest issue you have a certain number who may not accept the situation until it is clearly a disaster and is jeopardizing the crop.”

Weather has been a critical factor this summer, especially in the drought conditions that have persisted in the High Plains for the last four years.

“The severe drought has caused weed issues as well,” he says.  And it’s not just the effect dry soil has on herbicides, though that plays a role. “The drought has caused producers to reduce tillage to maintain crop residues for erosion control,” Siders explains. “This has increased the numbers of some weeds such as marestail, which is best control by tillage.”

And dry conditions limit herbicide efficacy. “The dry soil makes it difficult to achieve good incorporation of the yellow herbicides.”

Siders says a lot of factors “have conspired to get us into this current ‘weedy’ situation.”