Keep Your Cover Crops Legal

By Emily Unglesbee
DTN Staff Reporter

ST. LOUIS (DTN) — As harvest draws near, many farmers are experimenting with cover crops, but some may not fully understand the legal and liability issues that come with adding cover crops to a traditional cropping operation.

Cover crops are typically planted in the fall after a summer crop like corn or soybeans. The trouble arises when the herbicides used in the summer crops aren’t labeled to be followed by a cover crop.

The majority of corn and soybean herbicide labels categorize the wide variety of cover crop species as "other rotational crops" with plant-back restriction of 18 months. That means cover croppers can frequently find themselves operating "off-label," often without realizing it.

Farmers must remember that pesticide labels have the force of law, and operating outside of a label requirement is technically illegal, University of Wisconsin weed scientist Vince Davis told DTN.

For growers who use their cover crops as forage or feed, this off-label herbicide activity constitutes breaking the law. Growers who merely terminate the cover crop in the spring are operating legally, but they assume all the risk for the loss of that cover crop from herbicide injury, Davis noted.

"At the end of the day, what is on the label is law," Davis said. "It is very challenging to find out how to legally grow some cover crop species in a conventional ag system."


Plant-back restrictions on an herbicide label tell growers how long they must wait after an herbicide application to legally plant the next crop in their rotation.

These restrictions are based on residue level tests submitted by the company to the Environmental Protection Agency (EPA) for two purposes: to establish what level of herbicide residues are safe for human and animal consumption and to prevent herbicide injury to the following crop, Davis noted.

Because establishing safe residue levels for pesticide labels is time consuming and expensive, most companies only establish them for common rotational crops like corn, soybeans and wheat.

Very few available corn and soybean herbicides are labeled for the dozens of cover crop species that farmers can use, from radishes to peas and clover. Most cover crop species instead fall under the "all other rotational crops" category on an herbicide label, which usually defaults to a plant-back restriction of 18 months, Davis said.

According to the EPA, planting a cover crop species after an herbicide product that isn’t labeled for that species or planting before the 18-month plant-back restriction can be illegal, but only if the cover crop is used for feed.

"If a farmer allows animals to graze on it or if it is harvested for hay, there must be a tolerance (maximum residue level) for the pesticide on that crop," an EPA spokesperson told DTN in an e-mail.

Because cover crops are new to many farmers and this EPA stance isn’t well publicized, many cover crop growers in the U.S. might be technically breaking the law, Davis acknowledged.

"The instant a cover crop is grazed or harvested for hay, that makes it a forage crop, and then the farmer has to follow the label," he told DTN. "Unfortunately, there are probably more violations than we would care to have."


Farmers who don’t harvest their cover crop and instead burn it down in the spring can plant those cover crops after herbicide applications without breaking the law, the EPA noted.

"Cover crops (grasses, legumes, and other plants) are primarily planted for erosion control, soil structure health, moisture, and nutrient management," the EPA spokesperson wrote.

So as far as the government is concerned, when they aren’t harvested, "cover crops are not considered any particular food or feed crop and therefore would not fit into any of the crop groups" outlined on an herbicide label, the EPA added.

But that doesn’t mean these cover croppers are completely off the hook, Davis pointed out.

"The grower is still off label in terms of any support from the company," he warned. "If the label says there is a 10-month plant-back to rye, and (a farmer) does it in eight months and the rye doesn’t establish and he has a failed stand, the company has no fault."

Because of this liability issue, company representatives will never advise you to use a cover crop that isn’t listed on their herbicide label, even if you don’t have plans to graze or harvest it, Syngenta agronomy service manager Leslie Lloyd said.

"We can’t know for sure what he’s going to do with that crop," Lloyd told DTN. "We’re tightly bound by what the label says. If I make an off-label recommendation, I have violated federal law."

As a result, it can be hard for farmers to get advice on which herbicides to use or avoid for certain cover crop species. Even if a company rep knows the farmer might be able to follow their herbicide product with an unlabeled cover crop and not see any herbicide injury, they still won’t recommend it, Lloyd said.

"It’s not a matter of biologically getting away with it," he explained. "We have to adhere to the law. We don’t want to be jerks, but we can’t make off-label recommendations as stewards of these products."

Davis and the University of Wisconsin Extension have compiled this comprehensive guide to the plant-back restrictions for more than a dozen forage cover crop species after the use of most corn, soybean and small grains herbicides on the market:….

For growers who do not plan to hay or graze their cover crops this spring, the guide also highlights a short list of corn, soybean, and small grains herbicides that DO have rotational restrictions for cover crop species, such as Harness, Hornet and Python WDG.

Emily Unglesbee can be reached at

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