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Insecticides for Alfalfa and Grass: EPA's Interpretation

April 5, 2002
The United States Environmental Protection Agency (EPA) recently released an interpretation about the use of insecticides on mixed stands of alfalfa and grasses. Their interest in this issue pertains to some of the illegal applications of some insecticides in 2001 during the armyworm outbreak. Related to this issue, EPA also has questioned some published Extension recommendations in some states. EPA's interpretation is timely because the possibility for insecticide applications for control of early-season insects in alfalfa and grass will be on us soon.

Following is the verbatim text received (March 28, 2002) by the American Association of Pesticide Safety Educators from Jack Neylan, chief of the agriculture branch at EPA's Office of Enforcement and Compliance Assistance.

Crop Definitions With Respect to Pesticide Labeling

EPA Response to SFIREG Issue Paper and Inquiry from State of Vermont


1. Label interpretation issue: In the summer of 2001 the Vermont Department of Agriculture and several other Region I states became involved in investigating possible misuse of lambda cyhalothrin and other insecticides for army worm control on pastures. These investigations brought to light a number of questions regarding the applicability of label terms to the sites where applications had been made. For example, insecticides were used on alfalfa, for which they were labeled, and on grasses, for which they were not. A problem arises because there is a substantial amount of mixed stand alfalfa grown in this region, which may include alfalfa, clover and grasses. When Vermont asked registrants how they interpreted their labels when the terms alfalfa or alfalfa hay were used, responses were received ranging from "alfalfa means 100% alfalfa" to "anything over 51% alfalfa" to "if it is managed as alfalfa then it is alfalfa".

Acting through the State FIFRA Issues Research and Evaluation Group (SFIREG), the Region I states submitted an issue paper to EPA requesting clarification on how mixed stand crops should be accounted for in the registration process, and guidance for the states to assist with label interpretation.

2. Inappropriate recommendations on mixed stands. An example of the need to clarify the interpretation of what a label authorizes in the case of mixed stand crops arose when the State of Vermont found a publication issued by a university agricultural extension service that recommended the use of several insecticides for use against the alfalfa weevil provided that the stand was judged to be 51% or more alfalfa. Most of the insecticides being recommended were registered for alfalfa, but not for grasses. Vermont requested an Agency assessment of those recommendations.

EPA Response

The Office of Pesticide Programs (OPP) and the Office of Enforcement and Compliance Assurance (OECA) have reached the following conclusions, and plan the following actions, in relation to these issues.

1. Each component of a pasture crop does need to have a tolerance and be identified on the label as a use site. Thus, application of a product registered for alfalfa only to a mixed stand of alfalfa/clover/grass would be a use inconsistent with the label. This has enforcement implications for EPA's state regulatory partners. As with the misuse cases in 2001 involving Warrior, Lorsban and other insecticides on pastures, the Agency expects that in the event a state agency discovers that a mixed stand crop has been illegally treated, they will take appropriate measures to keep any potentially affected food or feed commodities out of the channels of trade until it is determined that no violative residues will occur.

Next steps: Through its Regional Offices and the communications networks of the Association of American Pesticide Control Officials (AAPCO), SFIREG, and the American Association of Pesticide Safety Educators (AAPSE), the Agency will disseminate this response paper throughout the regulatory and pesticide educational communities.

2. Many current products are not appropriately labeled. The Agency recognizes that only a few products registered only for alfalfa currently include the appropriate label instruction: "Apply only to fields planted to pure stands of alfalfa."

Next steps: EPA plans to notify and require registrants of products labeled for use on alfalfa to clarify their labels by incorporating the above limitation when there is only an alfalfa tolerance. At the same time EPA will encourage them to petition for a crop group tolerance for grasses that would cover all the forage grasses.

3. Inappropriate recommendations about treatment of mixed stand crops have probably been issued from various sources. OPP was able to locate a number of publications from various parts of the country containing recommendations for alfalfa that would lead to pesticide misuse, similar to the ones cited above. However, there are insecticides that have tolerances on alfalfa/clover/grass that may be effective against the alfalfa weevil namely, carbaryl, methoxychlor, malathion, methomyl, and methyl parathion.

Next steps: The Agency will continue to work with EPA Regional Offices, AAPCO and especially AAPSE, to disseminate information about this issue to extension service personnel and others who provide pesticide use advice to the agricultural community. It is also likely that alfalfa is not the only crop affected by this problem, and further cooperation between EPA, State regulators and educators, and the registrant community will be necessary to fully clarify and resolve these concerns.

If insects are causing injury to alfalfa, clover and/or grass hay this year and you are trying to determine which insecticide to use, please (here's that tried-and-true cliché) read the label! Let's try to avoid some of the difficulties with illegal insecticide applications that have occurred in other states.--Kevin Steffey

Author: Kevin Steffey

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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