Palmer amaranth is not the only herbicide resistant weed that creates headaches for Texas farmers.
Annual ryegrass, says Texas AgriLife Extension integrated pest management specialist Jim Swart, Commerce, “is the most widespread and damaging weed in winter wheat in Northeast Texas.”
It’s troublesome but not impossible to manage,” Swart says.
"Axial XL herbicide, marketed by Syngenta Crop Protection, has been the most effective product to control this pest, but its effectiveness has been diminishing in fields where it has been used year after year. Some strains of ryegrass have become tolerant to this herbicide, and they have become much more difficult to control."
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But it still can be effective in a two-part control program.
“University researchers in Northeast Texas have discovered a two-step herbicide program to help wheat producers control these resistant ryegrass plants,” Swart said. “Axiom herbicide, developed by Bayer CropScience, provides the first step. It has both pre-emergence and post-emergence activity and should be applied just as the ryegrass emerges from the soil."
“A good ‘rule of thumb’ is to apply Axiom when you can drive by the field and ‘row the wheat.’ It will usually provide 80 percent to 90 percent control of this pest. Follow that with Axial XL when the remaining ryegrass plants are in the two- to three-tiller stage. Axiom weakens the resistant ryegrass plants, making them more susceptible to the Axial XL application.”
The application rate of Axiom is 6 ounces per acre, and the rate of Axial XL is 16.4 ounces per acre.