Preharvest Weed Control: Scout Fields and Field Edges Now to Prevent Weed Seed Production

By Eric Yu

As harvest approaches, now is a good time to scout fields and field edges for weeds that escaped earlier control. Mowing fence lines, field edges and other non-crop areas can help prevent weeds from producing seed and reduce the potential for weed seeds to move into fields during harvest.

Despite the drier conditions across much of Minnesota this year, weeds continue to emerge and develop in fields and along field edges. Take time now to identify and manage these weeds before they produce additional seed and replenish the soil seedbank.

Scout for escaped weeds

Many weeds in corn and soybean fields are flowering or developing seed. Pay particular attention to waterhemp and other pigweed species, giant and common ragweed, kochia, common lambsquarters and annual grasses.

Waterhemp is especially important to manage because it can produce viable seed within 10 days of pollination and is capable of producing hundreds of thousands of seeds per plant (Bell & Tranel, 2010). Preventing weed seed production from even a few plants can reduce future weed pressure, for example lambsquarters has been reported to produce up to 30,000 seeds per plant.

When scouting, also check field entrances, roadsides, waterways, shelterbelts, low areas and other locations where weeds may have escaped control.

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