The spread of weeds resistant to multiple herbicides threatens Iowa’s crop production system. To slow the expansion of resistance, greater diversity in weed management is necessary. One alternative form of weed control being studied is to crush weed seeds as they come out of the back of the combine when crops are being harvested. Farmers in Australia are already using this type of weed seed destruction method.

An Oct. 21 workshop at Iowa State University will discuss this potential alternative weed-management tool that is used in other parts of the world: harvest weed seed control. 

“This clinic should be of interest to anyone interested in learning how farmers in other regions are adopting to the threat presented by herbicide resistance,” says Meaghan Anderson, ISU Extension field agronomist in central Iowa. “While the technology is not currently available for our system, it is likely these tools will be of value in the near future.”

Crush weed seeds, crush resistance

Harvest weed seed control is an alternative weed control tactic that targets weed seeds before they are shed from the plant. It uses the combine to intercept weed seeds and prevent them from entering the seed bank and contributing to future problems. This can be accomplished in several ways, including removing chaff from combines, grinding chaff and weed seed as they exit the combine, or windrowing or tramlining the chaff.

Michael Walsh is director of weed research at the University of Sydney, Australia, and an authority on harvest weed seed control, Anderson says. Australian farmers face some of the world’s worst problems with herbicide resistance and are rapidly adopting harvest weed seed control as a means of diversifying their weed management. 

Register by Oct. 14

Walsh and ISU Extension and Outreach will host a harvest weed seed control clinic at 10 a.m. Oct. 21 at the ISU Field Extension Education Laboratory. During the morning, the principles of harvest weed seed control will be discussed. After lunch, weather permitting, Walsh will demonstrate the types of combine modifications used to separate weed seeds from other materials entering the combine. The clinic will conclude by 3 p.m.

Attendees may receive up to four pest management certified crop adviser continuing education units for attending the morning and afternoon sessions (pending approval).  

While this clinic is free and open to the public, the ISU Extension weed management team asks that you please RSVP to Anderson at [email protected] or 319-331-0058 by Oct. 14 to ensure an accurate lunch count.

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