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Soybean Weeds

All Soybean Weeds Content

aerial view of South Dakota farm and surrounding land


During the growing season, SDSU Extension provides weekly production recommendations.

Marestail growing abundantly in a soybean field.

Marestail Fall Control

Marestail (also known as horseweed) is considered either a winter annual or biennial species that is often difficult to identify at the rosette stage. In the Dakota’s, marestail will germinate in the fall and bolt in the spring.

Tall, slender kochia weed growing in a test plot.

The Fall Advantage of Kochia Control

Kochia is a problem in north central South Dakota row crops. New post-emergent options in corn and soybean have helped alleviate kochia competition from many fields, but these herbicide options shouldn’t be completely relied upon for a long-term control plan.

soybean pods


SDSU Extension is your partner to increase yields and improve efficiency.

Paul O. Johnson making notes about a field of corn

SDSU Extension to Tackle Weed, Pest and Drought Inquiries at State Fair

August 23, 2021

To address drought concerns, as well as weed and pest inquiries, South Dakota State University Extension will feature two booth locations at the 2021 South Dakota State Fair Sept. 2-6 in Huron.

ALT: Left: Green Plamer amaranth next to a green sunflower. Right: Green plant with green, spiny structure at leaf base.

Palmer Amaranth: Now Is the Time to Scout

South Dakota State University (SDSU) Extension encourages farmers, ranchers and other landowners to start scouting for Palmer amaranth, a weed that has been rapidly spreading north into the United States and is likely to be glyphosate-resistant.

A soybean field with green soybeans and patchy yellow areas.

'Science for Success: Notes From the Field' Resumes Aug. 6

July 29, 2021

South Dakota growers and agribusiness professionals are invited to join soybean research and Extension specialists from land-grant universities across the country as they host the webinar series, "Science for Success: Notes From the Field."

plant with herbicide damaged leaves

Herbicide Damage to Fruits and Vegetables

Each year in early summer, many growers begin to notice distorted leaves on their fruits, vegetables, and crops. Most commonly the cause is a herbicide application to a nearby field.

Young corn seedlings emerging from a spring field.

Watch Closely for Weed Emergence

Cool, dry conditions have slowed weed emergence and growth, but dry conditions also have limited the activation of preemergent chemicals. Given this scenario, fields need to be scouted closely to ensure that weeds do not get away.

A farmer watching the sun rise in a bare, unplanted field.

Crop Tolerance to Soil Herbicide Residual

Some herbicides can persist in soil, especially dry soil. Herbicide carryover could be an issue in 2021 across the state depending upon last year’s moisture levels and field conditions.