Grazing cover crops following herbicide application

By Haley Johnson, MDA Pesticide Management Unit Supervisor, reviewed by Tana Haugen-Brown, UMN Pesticide Safety and Environmental Education Extension educator, and Sally Raymond, UMN Pesticide Safety and Environmental Education Extension educator

Before you graze – check this first

When planning to graze livestock on cover crops after herbicide use, it is critical to follow all pesticide label instructions. Understanding the distinction between different types of label statements is essential for making informed and compliant decisions. This is especially true given the presence of grazing livestock has been interpreted to mean that the crop is entering the food chain.

Many herbicide labels include one or both of the following:

• Plant-Back Intervals (PBIs): These indicate the minimum amount of time after a herbicide application before a particular crop can be planted. PBIs are designed to prevent crop injury due to herbicide residue in the soil.
• Rotational Crop Restrictions: These outline which crops may be planted following a herbicide application. These restrictions are intended to reduce the risk of herbicide carryover, pest or disease buildup, and herbicide-resistant weeds to ensure food safety.

When choosing cover crops for grazing, both PBIs and rotational crop restrictions should be reviewed. If a specific rotational interval is listed for a cover crop, and that interval has been met, the cover crop may be grazed/planted in most cases.

Some herbicide labels may present conflicting language. For example:

• One section may prohibit grazing or feeding forage from treated areas for 45 days following application.
• Another section may permit the planting of cover crops after harvest, but only if those crops are not grazed or harvested for food or feed.

These contradictions have raised concerns about whether it’s safe to graze cover crops in these situations. In such cases, the label restriction on grazing cover crops generally applies to species of plants that do not have an established PBI, or those for which no food or feed safety data are available. When a specific PBI is listed for the cover crop species and that interval is observed, grazing is generally considered acceptable.

When navigating conflicting label language, prioritize the use of pesticides with cover crops listed as use sites that contain clearly defined PBIs. Follow specified plant-back or rotational intervals and consider whether the crop will enter the food chain. Ensuring food safety and regulatory compliance should guide all cover crop and grazing decisions.

Pesticide Label Questions 

If you need assistance understanding or interpreting a pesticide label, contact Haley Johnson:

• Phone: 651-201-6440
  Email: Haley.Johnson@state.mn.us