New threat takes root

Kochia, a highly competitive weed that can reduce yields by as much as 70%, has been found in northwestern Missouri soybean fields.

While kochia is not new to Missouri, this may be the first time it’s been reported in cropland, said University of Missouri Extension weed scientist Kevin Bradley. Large scattered plants were found in Atchison County, likely making their way to the field via flooding of the Missouri River and its tributaries.

“I have never gotten calls or complaints about this species,” Bradley said. “I spend time actively looking for these kinds of situations and have never seen it in a Missouri corn or soybean field before.”

Kochia threatens yields, grows rapidly and aggressively outcompetes crops for water, nutrients and sunlight. It tolerates drought, produces up to 30,000 seeds per plant and germinates quickly—within two or three hours under the right conditions. It can emerge as early as February in this climate, and chemical control is difficult.

The biggest concern is that kochia may already be herbicide-resistant. In Kansas, Nebraska and the Dakotas, kochia is a “driver weed,” influencing management decisions in farming operations, Bradley said.

Management steps to help control the potential for kochia infestations include crop rotation, early control, pre-emergence herbicides in late fall or early spring and targeting small weeds after emergence. Fall cover crops may suppress establishment, and tillage disrupts roots.

If you suspect Kochia in cropland, contact your MFA agronomist or the MU Extension Plant Diagnostic Clinic.

Check out more stories in the August/September Today's Farmer Magazine.