South Dakota Weed Growth Concerns Increase

By Scout Nelson  

The planting season in South Dakota continues moving forward despite dry weather conditions and large temperature changes across the state. Farmers are making planting progress, but weed growth is becoming an increasing concern as waterhemp seedlings begin emerging in crop fields.

Eric Jones, Assistant Professor and SDSU Extension Weed Management Specialist, along with Philip Rozeboom, Jill Alms, and David Vos, highlighted that waterhemp seedlings have been observed in Volga, South Dakota (May 13, 2026), along with other areas across the state. They explained that dry weather has reduced the activity of preemergence herbicides, while warmer temperatures have allowed weeds to begin developing quickly.

Waterhemp is considered one of the most difficult weeds for crop producers because it grows rapidly and competes strongly with crops for nutrients, water, and sunlight. Experts note that under favorable conditions, waterhemp can grow between 0.5 inches and 1 inch per day. This means small seedlings can quickly become difficult to control if farmers delay management decisions.

Forecasted rainfall and warmer temperatures are expected to increase weed growth during the coming days. Weed specialists explain that waterhemp reaching 4 inches in height creates the ideal timing for herbicide applications. However, rapid growth may shorten the treatment window for farmers managing large acreages.

Fields that have not yet been planted or tilled may benefit from tillage practices to control newly emerged weeds. In no-till systems, burndown herbicide applications may become necessary before planting continues. Early postemergence herbicide applications may also help corn growers manage emerging seedlings before weed pressure increases further.

Specialists also encourage farmers to include residual herbicides in postemergence applications to help control later-emerging weeds during the growing season. Products such as Dual Magnum (S-metolachlor), Outlook (dimethenamid-P), and Warrant (encapsulated acetochlor) may help reduce future weed problems even though current dry conditions have limited herbicide activation.

South Dakota farmers are encouraged to review the South Dakota Pest Management Guides for additional recommendations on waterhemp and other weed management strategies this season.

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