Field Facts: Kochia
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Kochia is a summer annual weed that thrives in hot, dry weather. Populations of the weed have shown herbicide resistance in states across America and is capable of reducing yield by as much as 70% in row crops.1 Strong preemergence, residual herbicides are a powerful tool to protect corn and soybeans against kochia.
- Common names: Kochia, Mexican fireweed, mirabel, mock cypress
- Scientific name: Bassia scoparia
- Cotyledons: Lance- or linear-shaped, dull green and smooth
- Leaf shape: Lance- or linear-shaped, grayish green and flat with soft hairs
- Stems: Branched, round and purple to red in color with hairs
- Flowers: Green flowers with hairy bracts
- Reproduction: Monoecious (male and female attributes on one plant)
Fast facts
- Kochia is an early emerging summer annual weed. For example, it can appear as soon as February in Kansas.1
- The plant can be bushy and somewhat resemble the shape of a Christmas tree. Mature kochia plants grow upward of 7 feet tall, with an extensive root system that can extend 15 feet into the soil.1
- Young kochia plants may be confused with lambsquarters seedlings. Look for highly branched growth patterns with hairs occurring along leaf margins to identify immature kochia.
- Seed production is moderate to high with an adult kochia capable of producing up to 30,000 seeds.1
- The weed’s seeds spread via a “tumbleweed” mechanism, meaning a mature stem will detach from its base and then be blown around by wind.
- Seeds do not live long in the soil, but they possess a very high initial germination rate.
- Heavy infestations of kochia are known to cause as much as 70% yield loss in row crops. The plants also can interfere with harvest by getting tangled up in machinery.1
- Populations of kochia have been found with resistance to four herbicides: Group 2 (ALS inhibitors), Group 4 (synthetic auxins), Group 6 (photosystem II inhibitors) and Group 9 (EPSP synthase inhibitors).1
- According to WeedScience.org, herbicide-resistant kochia has been found in crops in 16 states. In addition, the weed has shown resistance to herbicides in noncrop areas like railways, roadsides and industrial sites in Indiana, Iowa, New Mexico and Utah.
Control tips
- Kochia is particularly difficult to control postemergence, so controlling it early in the season is key to preventing yield loss. Starting spring with tillage or a burndown herbicide application is essential.
- Experts advise applying the burndown shortly after the first flush of kochia has emerged.
- Following the burndown, use a two-pass program approach that includes preemergence and postemergence applications with multiple modes of action and residual activity.
- In corn, a good preemergence choice is SureStart® II herbicide followed by a timely postemergence application of Resicore® herbicide.
- In soybeans, Kyber™ herbicide is an excellent preemergence selection. DuPont™ EverpreX® herbicide can serve as a postemergence application for any soybean variety.
- For Enlist E3® soybeans, applying Kyber preemergence followed by a postemergence mix of Enlist One® herbicide and Liberty® herbicide can be a powerful program against kochia.
- It’s important to note kochia is very adaptable to hot, dry conditions. In drought or dry weather conditions, the weed can develop a thick cuticle around the leaves, which makes it harder to absorb herbicides. Using the right adjuvants can help with this.
- Rotation between grass and broadleaf crops can also help control kochia. Winter wheat is particularly good for suppressing the weed.1
1United Soybean Board. 2021. Kochia. https://iwilltakeaction.com/weed/kochia
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