We are looking for kochia seed to test for resistance!
While most farmers are dealing with typical weed issues like waterhemp, giant ragweed, and annual grasses, some are finding new weeds in their crop fields. While kochia has been present in Iowa for some time, it has remained primarily a weed of railroads and unmanaged areas until recent years. This year we have received more reports in crop fields and have sent some for testing for herbicide resistance.
Kochia (Bassia scoparia) is an early germinating annual weed, and one of the driver weeds in the Great Plains states, especially in small grains. In Iowa, early tillage and herbicide applications have typically provided effective control in row crops but increasing herbicide resistance and reductions in tillage have allowed it to persist in some fields. While most kochia germinates early, seedlings can emerge through mid-summer.
The seedling stage of kochia is called ‘button’ stage; seedling leaves are covered with dense pubescence that can decrease absorption of foliar herbicides. As plants grow larger, key identification traits include alternate, linear leaves with hair and three prominent veins visible from the underside of leaves. Plants are often a blue-green or gray-green color and can grow to about 4-5 ft. tall. This species is a tumbleweed that breaks off at the soil surface in the fall to assist in further distribution of weed seed.
Like waterhemp, kochia is known for multiple herbicide resistances. Biotypes resistant to combinations HG 2, HG 4, HG 5, HG 9, and HG 14 exist in U.S. populations. The Get Rid of Weeds (GROW) integrated weed management group has a document dedicated to kochia and provides significant information on plant biology and management strategies.
We are currently interested in determining where populations of kochia are persisting in crop fields and collecting seed from these populations where possible. Populations are often found in fields near railroads, possibly due to a combination of ease of spread on open railroad lines and the history of HG 2 herbicide use in these areas. Please reach out to your local Iowa State University Extension and Outreach field agronomist to help identify populations and submit seed for testing.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 9, 2026. The information contained within may not be the most current and accurate depending on when it is accessed.
- Field Agronomist in Central Iowa
- Assistant Professor
- Extension Weed Scientist Specialist