Harvest Planning Helps Farmers Reduce Weed Spread in Fields

By Scout Nelson

The 2025 growing season brought warm temperatures and heavy rainfall, creating ideal conditions for repeated weed germination across South Dakota fields. While late-emerging weeds have not caused major yield losses, their presence at harvest time requires careful management.

Farmers are encouraged to hand pull late-season weeds, as many contain viable seed. If left in fields, these seeds will return to the soil and increase weed problems in future seasons. Harvest planning becomes especially important in this context.

Fields should be scouted before harvest to assess weed severity. Cleaner fields should be harvested first, while heavily infested fields should be saved for last. If a weedy field is harvested first, seeds may become lodged in the combine and spread to other fields, increasing future weed pressure.

Small, isolated patches of weeds can be removed by hand, while unavoidable patches should be harvested separately with cleaning between fields.

Cleaning combines thoroughly is another critical step. Weed seeds can cling to machinery and later infest nearby fields. Any plant material removed during cleaning should be contained and destroyed to prevent further spread. Failure to clean equipment properly could create new weed infestations in surrounding areas.

Weeds also affect harvest efficiency. With higher moisture content than crops, weeds force combines to operate harder, using more fuel, slowing down harvest, and stressing machinery. While crop yields remain steady, these inefficiencies add to costs.

Farmers are encouraged to record the locations and types of weeds observed at harvest. This information will help guide effective weed management strategies for the next growing season. Consulting the South Dakota Pest Management Guides can provide further direction on herbicide options for different crops and weed species.

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