Source: AgriLife Today
Kochia, a kind of tumbleweed, has long been associated with the Texas High Plains, but its abundance is starting to alarm Texas A&M AgriLife officials as regional producers are experiencing challenges controlling kochia as herbicide resistance is mounting.
Muthu Bagavathiannan, Ph.D., Texas A&M AgriLife Research weed scientist in the Texas A&M Department of Soil and Crop Sciences, College Station, said kochia has been a major multiple herbicide-resistant weed problem for some time in parts of the Great Plains – Kansas, Colorado, Montana and surrounding states, and even in Canada.
Spreading their seed
Kochia is a summer annual plant, germinating in the spring and maturing in the fall. It is often the first weed species to germinate in the soil each spring, Bagavathiannan said. Thousands of seeds are produced on one plant and spread into the soil when the weed breaks free and begins to tumble.
Falling behind
Jourdan Bell, Ph.D., Texas A&M AgriLife Extension Service agronomist, Amarillo, said where kochia is sprayed along a fence line, producers often use a non-selective burndown herbicide and overspray into the highway right of way. This can result in bare soil along the highway right of way and a perfect environment for weeds to proliferate. If the kochia patches are already resistant to glyphosate, it further magnifies the problem.
Bell said she has received multiple calls from farmers in the area who faced kochia control failures with glyphosate, dicamba, metsulfuron and fluroxypyr and suspect multiple resistance to these herbicides.
Gaining control
Dotray agreed heavy reliance on fewer herbicide modes of action for kochia control is fueling the issue – management must include diversified options. Pigweed resistance in the Texas High Plains followed a similar pattern.
Bell said she stresses to producers that most branches on the kochia plant have a growing point so when they only “burn back” the plant, they will still have seed production from lower branches in addition to contributing to herbicide resistance due to partial control.
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