{"id":17299,"date":"2025-10-30T15:18:23","date_gmt":"2025-10-30T19:18:23","guid":{"rendered":"https:\/\/growiwm.org\/?page_id=17299"},"modified":"2025-11-13T14:59:44","modified_gmt":"2025-11-13T19:59:44","slug":"how-harvest-weed-seed-control","status":"publish","type":"page","link":"https:\/\/growiwm.org\/how-harvest-weed-seed-control\/","title":{"rendered":"Harvest Weed Seed Control"},"content":{"rendered":"
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Harvest Weed Seed Control<\/h1>\n\t\t\t
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What is Harvest Weed Seed Control?<\/strong><\/h3>\n<\/div><\/div>
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Harvest Weed Seed Control (HWSC) <\/strong>is the practice of capturing and managing weed seeds with harvest operations. At harvest time, combines can unintentionally turn into weed seed spreaders, due to weed escapes in the field that have produced seeds. If these weeds stand above the cutter bar, they can enter the combine during harvest. Most weed seeds exit the combine via chaff material. The combine then spreads these seeds behind it in the field in the chaff residues, creating a wider distribution of weeds for subsequent seasons.<\/p>\n<\/div><\/div>

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Harvest weed seed control tactics disrupt this weed seed dispersion by either destroying, confining, or removing weed seeds that enter the combine during harvest, impacting all seeds, herbicide-resistant weeds and non-resistant weeds alike. Harvest weed seed control can greatly reduce the number of weed seeds, as well as volunteer crop seed, entering a field\u2019s seedbank at the end of the growing season, reducing weed pressure in subsequent seasons. Ultimately, these kinds of management practices act as a backstop for weed control, giving farmers the final say for the season plus getting a jump on next seasons\u2019 weed control.<\/p>\n<\/div><\/div>

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While harvest weed seed control can be accomplished by a variety of methods, seed impact mills and chaff lining are the most common types in use today<\/a>. <\/p>\n<\/div><\/div>

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What are the Primary Systems of Harvest Weed Seed Control?<\/strong><\/h3>\n<\/div><\/div>
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Chaff Lining<\/strong>:<\/p>\n<\/div><\/div>

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Chaff lining<\/a> funnels the chaff portion (including weed seeds) into a narrow line behind the combine during harvest and left in place. Straw is still spread out as normal. This practice concentrates weed seeds into the chaff line<\/a>, (typically 12 to 18 inches wide). In those narrow bands across the field, weed seeds are less competitive than weed seeds spread across an entire field. Weed seed emergence is also often reduced in the chaff line. Chaff lining is a good entry-level harvest weed seed control option due to low upfront costs, the ability to work with any type of combine, and DIY-friendly construction requirements<\/a>.<\/p>\n<\/div><\/div>

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Seed Impact Mills<\/strong>:<\/p>\n<\/div><\/div>

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In this method, mills are attached to the back of the combine to crush and process the chaff residue, injuring or destroying any weed seeds within the chaff, before spreading it back across the field. This system returns all residue to the field evenly in a single pass. This technology is usually considered the ultimate form of harvest weed seed control<\/a>, but it comes with significant upfront costs and requires a Class 8 or larger combine.<\/p>\n<\/div><\/div>

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Select the buttons below to learn more about seed impact mills<\/strong> and chaff lining<\/strong>.<\/p>\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\tAre there other systems for harvest weed seed control?\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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There are four other methods of harvest weed seed control<\/strong> in use today, though less common than seed impact mills and chaff lining.<\/p>\n

Four of the six HWSC systems\u2014chaff lining, seed impact mills, chaff tramlining, and chaff carts\u2014target only the chaff<\/strong>, whereas bale direct and narrow windrow burning target both the chaff and the straw residues leaving the combine. Many combines require the installation of a baffle to keep the chaff and straw separate. For a quick overview of the pros and cons of each method, see Figure\u00a01.<\/p>\n

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Chaff cart. Photo credit: Michael Flessner, Virginia Tech<\/figcaption><\/figure>
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Chaff Tramlining:<\/strong> Here, chaff is funneled into narrow rows that align with the two wheel tracks of a farmer\u2019s equipment. In a \u201ccontrolled traffic farming system,\u201d a grower uses only these dedicated wheel tracks\u2014or tramlines\u2014as they move equipment through the field. This reduces overall soil compaction and produces an unfavorable environment for weed seeds within the tramlines, due to factors such as soil compaction and plant injury from equipment.<\/span><\/p>\n

Chaff Carts:<\/strong> Imported from Canada, chaff carts (sometimes called \u201cchaff wagons\u201d) follow behind a combine and collect chaff harvest materials, where most weed seeds end up. Chaff can be dumped in the field for subsequent management or removed from the field. Chaff can be a valuable feedstuff for livestock.<\/p>\n

Bale Direct:<\/strong> A baler is attached directly to the combine, which bales chaff and straw residues as well as weed seeds in the harvest residues. If a market exists for them, the bales can be sold for bedding or livestock feed.<\/p>\n

Narrow Windrow Burning:<\/strong> In this method, all harvest residues\u2014including chaff, straw, and weed seeds contained within them\u2014are funneled into a narrow row, where weed seeds can be destroyed by burning. This method has proven effective at destroying weed seeds<\/a>, but comes with significant fire risks and other trade-offs to soil health. Local burning regulations may also exist.<\/p>\n

Watch this video clip<\/strong> of narrow windrow burning:<\/p>\n