Source: Dallas Peterson, Weed Management Specialist and Curtis Thompson, Weed Management Specialist, Kansas State University Extension
As of mid-March, kochia was emerging in wheat and wheat stubble in western Kansas. Much of the wheat stands in that area are thin and the early growth is below average. As a result, it is possible for kochia to grow taller and to be even more competitive than usual this year, reduce yield, and pose a serious problem by harvest time if left uncontrolled.
Challenges to getting good control of kochia
It is not always easy to control kochia in a standing wheat crop, however. There are four big challenges to kochia control in wheat:
- There are many populations of kochia with resistance to either ALS-inhibitor herbicides, atrazine, or glyphosate. There may even be some populations resistant to dicamba.
- A majority of kochia emerges early in the spring, but some emergence can extend over a period of weeks or months. A herbicide applied early in the spring will need to have residual activity to be effective on later-emerging kochia. Several ALS-inhibitor herbicides have good residual activity, but are ineffective on ALS-resistant kochia.
- Dicamba, a non-ALS herbicide and one of the more effective products on most populations of kochia, must be applied before the jointing stage of wheat, meaning that later-emerging plants may not be controlled.
- Most other non-ALS herbicides that can be applied at a later growth stage of wheat are primarily contact herbicides that require thorough coverage to be effective, and this can be difficult to achieve when the wheat canopy gets larger and covers up some of the kochia present. Two exceptions are Huskie and Starane. Those two products can be applied at later growth stages of wheat, are translocated (Starane more so than Huskie), and are effective on kochia.
[Editor's Note: Goldsky is highly useful for kochia control, too.]