No. 8 Article 1/May 15, 2009

Applying Soil-Residual Herbicides After Corn Planting and Emergence

Soil-residual herbicides, an important component of an integrated weed management program, reduce the potential for corn yield loss caused by early-season weed interference and help reduce the selection intensity for herbicide-resistant weed biotypes. Most often these products are applied shortly before or after planting but before corn emerges. Given the planting challenges imposed on Illinois corn farmers by this season's unfavorable weather, it is altogether likely that some, even many, fields were planted before a soil-residual herbicide was applied. In some instances the corn has not yet emerged, whereas in others it has. If you still intend to apply a soil-residual herbicide, take note of these general considerations:

Corn is planted but not yet emerged:

Corn is planted and has emerged:

Whatever the scenario, always remember that soil-residual herbicides need to be moved into the soil solution to be available for uptake by weed seedlings. A herbicide that remains on the soil surface after application and is not moved into the soil profile by precipitation or mechanical incorporation may not provide adequate weed control.--Aaron Hager

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