Herbicide interactions

The effect of herbicides on cover crop establishment

Commonly applied corn and soybean residual herbicides have the potential to injure cover crops planted after the herbicide application. Often herbicides have a rotational interval for the following crops stated on the label . However, few labels include cover crop data on them. Often herbicide carryover injury goes un-noticed or herbicide effects are attributed to other conditions.

Researchers at UW-Madison evaluated several residual herbicides’ impact on cover crops.  They evaluated a wide range of common corn and soybean herbicides on several cover crops.  Click here to view results.

Herbicides and cover crops used as a forage

Although, the impact of residual herbicides on cover crop establishment is important for growers to consider, perhaps more important is making sure herbicide programs are compatible with cover crops that will be fed or grazed.
This publication provides guidance on Herbicide Restrictions for cover crops that will be used as a forage.

Here are a few other relevant publications for herbicide restrictions when using fall or spring seeded cover crops:

Forage Herbicide Quick Sheet: Cereal Rye Forage after Corn Silage (WCWS 203)

Forage Herbicide Quick Sheet: Spring-Seeded Forages after Corn (WCWS 202)

Herbicide issues with interseeding cover crops early in the growing season

A major challenge with interseeding is compatibility with a residual herbicide program.  We do not have a Wisconsin Extenison publication on compatibility between herbicides and cover crops for interseeding but Penn State has developed recommendations.  Please see their publication that is linked below.
Improving Success with Interseeding

Resources from other states

The Effects of Residual Herbicides on Cover Crops- University of Missouri

Residual Herbicides and Fall Cover Crop Establishment- Purdue

Herbicide Carryover and Persistence Table- Penn State Recommendations


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