{"id":17346,"date":"2025-10-30T15:19:16","date_gmt":"2025-10-30T19:19:16","guid":{"rendered":"https:\/\/growiwm.org\/?page_id=17346"},"modified":"2025-11-13T15:00:46","modified_gmt":"2025-11-13T20:00:46","slug":"seed-impact-mills","status":"publish","type":"page","link":"https:\/\/growiwm.org\/seed-impact-mills\/","title":{"rendered":"Seed Impact Mills"},"content":{"rendered":"\n
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Seed Impact Mills<\/h1>\n\t\t\t
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Seed impact mills <\/strong>are a harvest weed seed control device designed to crush crop residues and chaff material leaving the combine, including weed seeds. There are three major brands in use in North America today: the Integrated Harrington Seed Destructor<\/a> (iHSD), the Redekop Seed Control Unit<\/a>, and the Seed Terminator<\/a>. University testing shows very high weed seed kill rates from seed impact mills, but harvest conditions, crop type, and climate can significantly impact how well they work. Open each accordion below to learn more.<\/p>\n<\/div><\/div>

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A seed impact mill called the Seed Terminator at work in a wheat field in Washington state. (Photo credit: Claudio Rubione, GROW)<\/figcaption><\/figure>\n<\/div><\/div>
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\n\t\t\t\t\t\t\t\t1.<\/span>\n\t\t\t\t\t\t\t\tHow do seed impact mills work? \t\t\t\t\t\t\t<\/h4>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<\/div>\n\n\t\t\t\t\t\t
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The finely ground remains of chaff residue after it has been run through a seed impact mill. (Photo credit: Michael Flessner, Virginia Tech)<\/figcaption><\/figure>\n

Mills process only the chaff portion<\/strong> of harvested material, which is what comes off the sieves (also known as the shoe). The straw fraction is not processed. This design is effective because research shows that weed seeds are found predominantly in the chaff. For example, GROW network testing shows less than 5% of weed seeds escape control by exiting the combine in the straw material (see Section 2. How well do seed impact mills kill weed seeds?<\/em>).<\/p>\n

During harvest, chaff material and weed seeds enter the center of the seed impact mill and pass through rings of spring bars or screens (rotors<\/em>) and stationary bars or screens (stators<\/em>) to exit the mill. The rotors spin at about 3,000 rotations per minute. Weed seeds must hit the steel four times or more before exiting. Most seeds are shattered into multiple, non-viable fragments. Sometimes whole seeds pass through with fatal damage to internal organs, leaving them non-viable. In other cases, seed coats are cracked, exposing seeds to elements and pathogens, which significantly lowers germination potential.<\/p>\n

See a short video demonstrating how seed impact mills work with a Redekop model:<\/p>\n