- Common names: Kochia, Mexican fireweed, mirabel, mock cypress1
- Scientific name: Bassia scoparia (L.)1
- Grass or broadleaf: Boadleaf
- Found in 45 U.S. states (not found in Alabama, Arkansas, Florida, Georgia or Maryland)1
- Germination timing: Summer annual
- Competitiveness: Highly competitive. Kochia that is not controlled early in the season with tillage or a burndown herbicide tends to cause problems throughout the growing season, according to Kristin Rosenbaum, Ph.D., field scientist, Dow AgroSciences.
- To distinguish kochia from other species, make note of the highly branched nature of the weed, and the hairs that occur along the leaf margins. Although biotype-dependent, young kochia seedlings may be confused with common lambsquarters seedlings.
- Kochia can be bushy and resemble the shape of a Christmas tree in appearance. This weed, which can grow taller than 7 feet, has an extensive root system.
- Seed production is moderate to high, depending on environmental and competitive conditions. Seed dispersal occurs via a “tumbleweed” mechanism, in which the mature stem detaches from its base and is subsequently blown about by wind. Kochia seed is short-lived in the soil, but possesses a high initial germination rate.
According to WeedScience.org, the following states have reported herbicide-resistant kochia in cropland, corn and soybean fields:
- EPSP synthase inhibitors
- ID, KS, MT, ND, NE, OK, OR, SD
- ALS inhibitors
- KS, MN, MT, ND, SD
- Photosystem II inhibitors
- CO, IL, KS, ND, NE, WI, WY
- Synthetic auxins
- CO, MT, NE
Multiple resistance: two sites of action
- ALS inhibitors and photosystem II inhibitors
- ALS inhibitors and EPSP synthase inhibitors
- EPSP synthase inhibitors and synthetic auxins
Multiple resistance: four sites of action
- ALS inhibitors, photosystem II inhibitors, EPSP synthase inhibitors and synthetic auxins
*Resistance confirmation does not necessarily include all weeds and may vary among different areas of each state.
Weed management tips:
- Recent trends. The recent development of kochia populations resistant to ALS, glyphosate and/or triazine herbicides is causing corn and soybean growers to put forth extra time and effort controlling this tough summer annual broadleaf weed. Control can still be achieved in both corn and soybeans, especially if a combination of herbicides is used with different modes of action early in the spring.
- Tolerates early frosts and hot weather. Kochia can emerge early in the spring and its seedlings can survive early frosts. Kochia also thrives in hot weather and can continue to germinate throughout the growing season. Due to its emergence patterns, an effective burndown herbicide and residual herbicide is necessary to extend control of kochia into the growing season.
- Start with tillage or a burndown herbicide. Corn and soybean growers should begin with either tillage or a burndown herbicide application in early spring, shortly after the first flush of kochia has emerged.
- If growers wait to apply the burndown and preemergence herbicide in the same application, kochia can grow larger and growers may not achieve effective control. If that occurs, the surviving plants will go on to cause problems throughout the growing season. Therefore, it is risky to wait to apply a burndown with a preemergence herbicide in fields where kochia is a problem.
Dow AgroSciences weed control solutions:
SureStart® II herbicide
Keystone® NXT herbicide
Keystone® LA NXT herbicide
FulTime® NXT herbicide
Surpass® NXT herbicide
Durango® DMA® herbicide
Enlist Duo® herbicide, as part of the Enlist™ weed control system
More information can be found through these weed science resources: