State to allow use of methyl iodide

SACRAMENTO
December 1, 2010 2:01pm

Registration of the agricultural chemical methyl iodide will occur later this month as soon as emergency regulations take effect to designate the fumigant pesticide as a restricted material, California Department of Pesticide Regulation Director Mary-Ann Warmerdam says Wednesday.

The decision follows the U.S. Environmental Protection Agency’s approval of California-specific labels for four methyl iodide products with “stringent health-protective measures” required by DPR, the department says.

Restricted materials require a use permit from the agricultural commissioner in the county where the application is planned. State pesticide laws are enforced by county agricultural commissioners, who can impose tougher restrictions tailored to local conditions.

“Methyl iodide can be used safely under our tough restrictions by only highly trained applicators at times, places and specific conditions approved by the county agricultural commissioners,” says Ms. Warmerdam.

California’s use restrictions on methyl iodide are more stringent than those required by U.S. EPA, Florida and other states where it is applied, the state says. U.S. EPA registered methyl iodide in 2007 as a replacement for methyl bromide, which causes damage to ozone in the upper atmosphere. Methyl iodide does not harm the ozone layer.

Methyl iodide will be legal for use in California after the emergency regulations take effect in late December. The emergency regulations are necessary so methyl iodide can only be used with a permit from the county agricultural commissioner.

“We acknowledge there are strong and diverse opinions on methyl iodide registration,” says Ms. Warmerdam. “Methyl iodide is a chemical designed to kill pests and soil-borne diseases. We based our decision on the risk assessment by our scientists and a risk-management process that determined what measures are required to keep exposures to methyl iodide within safe levels. With these safeguards, methyl iodide can be used without exposing workers and the public to harmful levels.”

Use restrictions include stricter buffer zones, a requirement that only DPR-approved highly retentive tarps be used, more ground water protections, reduced application rates and stronger protections for workers, the DPR says.

In addition, DPR will conduct sampling of water and soil in areas with high methyl iodide use to monitor the effectiveness of the mitigation measures.

Methyl iodide, also called iodomethane, is licensed for use in 47 other states. Injected into soil before crops are planted, the fumigant spreads through the soil to kill weed seeds, plant diseases and nematodes. It can be applied by drip irrigation under a special protective tarp or injected into the soil using a tractor that automatically places a tarp over the ground after application.

Methyl iodide products are made by Arysta LifeScience Corp. and sold under the brand name Midas. The major uses of methyl iodide in California are to treat soil where strawberries, nursery plants and nut trees are to be planted.