Noxious Weed of the Month
Kochia (Kochia scoparia)
Kochia is considered a serious pest in late-maturing crops, cereal crops, to livestock producers, and in areas where it can increase fire hazard.
Once deemed "the worst weed in the west", kochia is an escaped ornamental introduced to North America from Europe, where it is native to southern and eastern parts of Russia. While it was originally prized as a hedge or backdrop landscaping plant, kochia has escaped cultivation and is able to rapidly disperse itself over long distances. Kochia is a serious threat to late-maturing crops like soybeans and sugar beets and in the fallow portion of cereal-fallow systems. Early emergence of kochia can be a problem in cereal crops as well. Kochia reduces agricultural yield by outcompeting crops for light, nutrients, and soil moisture. Large stands of kochia increase fuel loads and fire hazard and can obstruct right-of-ways and reduce access. Additionally, kochia is toxic to livestock including equines, cattle, sheep, chickens, and possibly goats, alpacas, and llamas. All parts of the plant are toxic, including when dried in hay. Recovery with treatment is possible from mild intoxication but liver and nitrate toxicity are often fatal.
Kochia is highly adaptable, drought tolerant, and can grow in a wide variety of soil types- even salty soils. Because of this ability, kochia can be found on pastureland, rangeland, roadsides, ditches, wastelands, and in cultivated fields. Kochia grows rapidly through spring and summer and sends down a taproot that can be as long as 16 feet before it flowers in the summer. Each plant produces around 14,600 seeds, which have a germination rate of 76% or better in temperatures ranging from 39-106 degrees Fahrenheit. Seeds are dispersed in the fall when the mature kochia plant becomes a tumbleweed, dropping seeds as it is blown about. Kochia seeds tolerate frost, overwintering and germinating early in the spring.
Kochia was listed as a Class B noxious weed in Washington State in 1988. The Class B status means that control is required by the state in counties where control is feasible- currently, control of kochia is required by the WSNWCB in 22 counties in Washington. In counties where control is not required, the County Noxious Weed Control Board may select kochia for mandatory control to meet local needs and priorities. All County Noxious Weed Control Boards can provide educational and technical assistance for landowners interested in voluntary control. You can control kochia- many methods, including cultural, mechanical, and chemical, can be effective in controlling kochia infestations when used as a part of a broader Integrated Pest Management plan. Your County Noxious Weed Control Board can assist you in choosing appropriate methods.
Kochia can form dense stands, like this spreading infestation of young plants, that outcompete desirable plants and increase fuel load.
How to Identify
Kochia is an erect, bushy summer annual with many leafy branches. Its alternate, narrow, lance-shaped leaves have hairy margins & undersides. Kochia stems are round, usually soft-hairy and often red–tinged and striped. In the summer, kochia produces inconspicuous green flowers which form dense spikes in leaf axils and are often surrounded by clusters of long hairs. Kochia, a member of the Chenopodiaceae family, becomes a tumbleweed when mature.
|Kochia seedlings as compared to a quarter.||Close-up of a kochia leaf.||Kochia leaves, showing alternate pattern and hairy stems.|
|Kochia flowers are small, green, and unremarkable.||Note the clusters of long hairs that are often surrounding the small green flowers.||Kochia stems are often red-tinged and striped.|
|Adult kochia plant displaying orange-red stems.||Adult kochia plant displaying pink-red stems.||Adult kochia plant displaying green stems.|
Table photos used courtesy of the Stevens County Noxious Weed Control Board
Ways to Help
- Control kochia plants on your property.
- Contact your local County Noxious Weed Control Board for information about local volunteer opportunities.
- Encourage friends and family to be on the lookout for kochia and other noxious weeds.
- Share your knowledge!