With the 2026 wheat harvest in full swing it is time to think about weed control in wheat stubble. When soil moisture conditions are favorable, weeds that have been suppressed by the canopy will grow rapidly once crop competition is removed. In addition, weeds that have emerged through the wheat canopy will be damaged during harvest and will quickly begin regrowth. Delaying control can result in lost soil moisture that could be used for crop production, as well as weed seed production, which will cause difficulties in the future.
When thinking about weed control in wheat stubble, there are two priorities – controlling already emerged weeds and preventing later flushes. Making applications before weeds exceed 4 to 6 inches is necessary for good control of already emerged weeds. Residual herbicides are recommended to reduce the number of herbicide applications required to control multiple flushes of weeds.
Despite a growing number of herbicide-resistant weeds, glyphosate plus 2,4-D LVE and/or dicamba continue to be important for weed control in wheat stubble. However, these herbicides alone are not likely to provide adequate control of pigweeds or kochia, especially when applied in the hot, dry conditions that are common after wheat harvest. Some herbicide options commonly used to control weeds after wheat harvest are: Paraquat (Gramoxone, others), metribuzin, saflufenacil (Sharpen), tiafenacil (Reviton), flumioxazin (Valor, others), and sulfentrazone (Spartan, others). To read the full article which goes into more detail on each herbicide option, search for Extension Agronomy eUpdates, which you can also subscribe too.
One final note regarding paraquat. Limited research out of Australia suggests applying paraquat 2 weeks after a glyphosate application will increase weed control. This is called a ‘double knock’ strategy. This information is included here not as a recommendation per se, but to encourage careful thought about when you want to utilize contact herbicides in your fallow weed management system. If paraquat were sprayed with or before glyphosate, the rapid damage to leaf tissue with prevent uptake and translocation of glyphosate. However, if a glyphosate application partially controls weeds, there will be sufficient leaf area 2 weeks after application for paraquat to be effective. Research to evaluate Palmer amaranth control in wheat stubble was conducted in Hays during 2019 and 2020. Herbicides were applied approximately 3 weeks after harvest to Palmer amaranth that was two to three feet tall. Palmer amaranth control 4 weeks after application in general, treatments that included paraquat (Gramoxone) resulted in the greatest Palmer amaranth control.
For more information, you can search for the 2026 Chemical Weed Control for Field Crops, Pastures, Rangeland, and Noncropland, K-State publication SRP-1194 as well. Information provided by K-State weed control specialists.
Stacy Campbell is a Crop Production Extension agent in the Cottonwood District (which includes Barton and Ellis counties) for K-State Extension. You can contact him by e-mail at scampbel@ksu.edu or by calling 785-628-9430.