Figure 1. Emerged kochia. Photo: K. Gustafson, Agronomy Professional
S.D. Wheat: Kochia issues
Warm temperatures across South Dakota this spring has allowed kochia to get a head start in many areas and wheat fields are no exception. Most spring wheat in the state is already been planted. If kochia plants were present at spring wheat planting it would be best to apply a burn-down treatment before crop emergence. A great example of when early emerging kochia is a problem would be the picture above (Figure 1) that I received April 6 from an agronomy professional where there were numerous kochia seedlings present. If no burn down treatment was performed in spring, then a timely application this spring would give wheat the advantage. Most, if not all herbicide labels that provide good or great control of kochia POST in wheat require it controlled before the kochia reaches 4 to 8 inches tall (depending upon label requirements), but larger than 1 inch for better coverage.
If the kochia present has ALS (prosulfuron) resistance than the following, would be the best suited in wheat for control of kochia POST emergent. The chemicals in an SDSU test that had excellent control included one or more combinations of the following: Fluroxypyr, Bromoxynil, Clopyralid or Diglycolamine. Chemicals that had good control would include one or more combinations of the following: Bromoxynil, Pyrasulfotole, Dicamba, 2,4D, MCPA or Carfentrazone-ethyl.
Be aware that the chemicals in the excellent category of controlling kochia in wheat are only using one or two sites of action (group 4 and 6). It would be wise to make sure to tank mix other sites of action in the next cash crop in the rotation or tank mix with other profitable chemicals listed above.
For more information on chemical options for small grains, refer to the 2017 South Dakota Pest Management Guide: Wheat.