Kochia is an early emerging summer annual weed species that can be problematic for most of the corn- and soybean- producing areas. Timeliness and herbicides with multiple sites of action provide growers the most effective chance at controlling this weed species. Residual herbicides applied late in the fall have proven to be very effective on spring kochia emergence; however, effective spring management is critical when a fall program was not used.
When considering kochia control in the late winter or early spring, special attention should be given to minimum soil temperature. It has been shown that kochia will germinate when minimum soil temperatures reach 39° F and can survive at temperatures well below freezing. Relying on a pre-plant, pre-emergence or post emergence herbicide program for kochia control can be unreliable as plants are rapidly growing and may prove difficult to control (Figure 1). A burndown and residual herbicide combination is effective on this species from late February through March depending on local conditions. Some kochia populations have developed resistance to multiple herbicide groups across the Corn Belt including ALS, plant growth regulators (2,4-D and dicamba), atrazine and glyphosate.1 Using a combination of a burndown herbicide and herbicide products with soil residual activity such as atrazine, isoxaflutole and others offers good coverage for early season kochia control. Read and follow herbicide label requirements and recommendations as local conditions, suitability and crop rotation limitations differ by geography. To be effective, kochia control measures should be made early in the season when weeds are small and utilize an herbicide with multiple sites of action.
1Thompson, C. Kochia control. Sunflower District. K-State Research and Extension. Kansas State University. https://www.sunflower.k-state.edu/.
Werle, R. 2017. Q&A: When is the best time for kochia control. CROPWATCH. University of Nebraska-Lincoln. https://cropwatch.unl.edu/.
Shaffer, G. 2019. The fall advantage of kochia control. SDSU Extension. South Dakota State University. https://extension.sdstate.edu/.
Web sources verified 12/20/19
Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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