State pesticide regulators proposed Friday that methyl iodide, a controversial fumigant that would be largely used by strawberry growers, be registered for use in California.

The proposal, announced by Department of Pesticide Regulation Director Mary-Ann Warmerdam, includes application restrictions that would be much more stringent than in the rest of the nation. The restrictions include such things as wider buffer zones, lower exposure thresholds and less-intensive applications on fields being treated.

The proposal, which could be made final by late summer or early fall, was sharply criticized by Paul Towers, state director of the group Pesticide Watch.

“Our interpretation of the science is that methyl iodide is unsafe at any rate for use in California,” he said. “We believe California has taken a step backward in terms of protecting health and the environment.”

Methyl iodide is seen by some as a potential replacement for methyl bromide, a commonly used soil fumigant whose use is being phased out internationally because it damages the ozone layer.

Strawberry growers will welcome Friday’s news, but given methyl iodide’s cost and restrictions on its use, they would not likely use it to the extent that they used methyl bromide, said John Krist, Ventura County Farm Bureau chief executive officer.

“This is a very expensive tool in the arsenal,” Krist said. “It is not likely to be a great option for smaller growers.”

Although methyl iodide, which is applied to soil before planting to kill insects and fungi in the ground, has other uses, its most common application in California likely would be on strawberry fields. Growers in Ventura County had been among the most intensive users of methyl bromide in the state, applying 835,000 pounds over 4,634 acres in 2007.