The Mississippi Department of Agriculture and Commerce has obtained an emergency exemption for metolachlor, a herbicide that is not labeled for sweet potatoes but provides effective control of annual grasses and certain broadleaf weeds.

Syngenta Crop Protection manufactures metolachlor under the trade name Dual Magnum. The exemption is effective May 5 and expires July 15. The department received approval for the exemption from the U. S. Environmental Protection Agency on April 8.

"Farmers will be able to make applications before weeds can emerge, which will allow them to prevent yield reductions and harvest efficiency problems," said Mississippi Agriculture Commissioner Dr. Lester Spell.

The state agriculture department has authority under Section 18 of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) to obtain an emergency exemption for a non-labeled use of a pesticide if significant losses of an agricultural commodity are likely and alternative, registered products are not available or effective.

The department administers the provisions of a Section 18 exemption through the Bureau of Plant Industry.

According to weed specialists with the Mississippi State University Extension Service, metolachlor is particularly effective against yellow nutsedge, one of the 10 worst weeds affecting sweet potato production in the state.

Farmers needing more information can contact Benny Graves at the Mississippi Sweet Potato Council at (662) 325-3390 or Extension agronomist Bill Burdine in Houston at (662) 456-4269.

e-mail: patti@mdac.state.ms.us