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Evidence That Combines Can Transport Weed Seeds

Updated October 06, 2023

Eric Jones

Assistant Professor and SDSU Extension Weed Management Specialist

Additional Authors: Philip Rozeboom
Four pictures of a red combine with tan and black soybean and weed seeds spread throughout its surfaces.
Figure 1. Various areas on a combine where weed seeds have been deposited. The weed seeds can easily dislodge and be distributed within fields being harvested, highlighting the importance of cleaning the combine and containing any residues after cleaning.

Written collaboratively by Eric Jones, Philip Rozeboom, Jill Alms, and David Vos.

A combine deliberately harvests crop grain, but it can also unintentionally transport weed seeds. Weeds present in crop fields at the time of harvest usually possess seeds. The seeds from the weeds are small and can get lodged or placed all over the combine (Figure 1).

Evidence from Figure 1 highlights the importance of cleaning the combine of weed seeds when changing fields and at the end of the season. Containing the weed seeds before leaving the combine and returning to the soil is important, and these seeds represent weeds that will have to be controlled in the growing seasons to come. Every seed that is removed from the field is another weed that will not have to be controlled later.

Areas of the combine that can be easily reached can simply be swept off. Harder-to-reach areas can be cleaned with compressed air or water. Any soil on the combine should be cleaned off as well, as the clods could contain weed seeds as well. While cleaning the combine of weed seeds is important, containing the residues after cleaning is equally important. The residues from cleaning need to be contained and destroyed so that weed seeds are not allowed to disperse in nearby fields.