As we head into fall, some producers are thinking about seeding winter cover crops in fields currently planted to corn. The successful establishment of winter cover crops is influenced by several factors discussed in last week’s eUpdate article “Planting cereal rye after corn harvest.” This article will provide some additional details about cover crop responses to various herbicides.
A number of factors, including biological and biochemical characteristics of the plant, chemical characteristics of the herbicide, and weather conditions since herbicide application will influence cover crop response to herbicides. Table 1 summarizes the response of selected cover crops to selected herbicides. For simplicity, no herbicide premixes are included in the list. The responses are cautious/conservative estimates based on published field research, herbicide labels, and a recent publication from the Take Action campaign. A field bioassay is the most reliable method to determine crop response to potential herbicide residues. A bioassay is an easy at-home test to see how your seeds will grow in the field soil.
Table 1. Likelihood of injury to selected cover crops when planted in the fall after a spring application of selected corn herbicides. Green = injury unlikely; Yellow = injury possible; Red = injury likely.
|
Herbicide |
Cereal rye |
Wheat |
Red clover |
Hairy vetch |
Radish |
|
Atrazine |
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Balance Flexx, (isoxafluotle) |
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Callisto (mesotrione) |
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Dual II Magnum (S-metolachlor) |
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Harness (acetochlor) |
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Outlook (dimethenamid-P) |
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Prowl H20 (pendimethalin) |
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Sharpen (saflufenacil) |
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Valor (flumioxazin) |
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|
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Zidua (pyrasulfoxone) |
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An often overlooked fact is that potential crop response is not the only factor determining planting intervals. Sometimes, the potential for herbicide residues in the harvested product is the limiting factor. As such, cover crop planting consideration after certain herbicides may be different if grazed. For example, herbicides containing acetocholor, dimethenamid, and pyroxasulfone have very little potential for cover crop injury but may contain herbicide residues if grazed.
The use of trade names is for clarity to readers and does not imply endorsement of a particular product, nor does exclusion imply non-approval. Always consult the herbicide label for the most current and updated use requirements.
References
Brooker, et al., 2020; Cornelius and Bradley, 2017; Palhano, et al., 2018; Price, et al., 2020; Rector, et al., 2020; Wallace, et al., 2017
Sarah Lancaster, Extension Weed Science Specialist
slancaster@ksu.edu
DeAnn Presley, Soil Management Extension Specialist
deann@ksu.edu
Peter Tomlinson, Environmental Quality Extension Specialist
ptomlin@ksu.edu
Tags: cover crops herbicides herbicide carryover termination