The soil fumigant methyl bromide, which growers have depended on for decades, will no longer be available starting in 2015. Methyl iodide, a potential substitute, is a harmful chemical, but can be used safely with proper precautions, said UC Cooperative Extension weed scientist Steve Fennimore.
"The professional fumigators are really good," Fennimore said. "If the public saw how the companies do the fumigation, they'd probably be more comfortable with them."
Another fumigant, chloropicrin, is widely used in combination with methyl bromide and methyl iodide to provide the most pest-free soil for growers.
"Chloropicrin is really strong against fungi, and methyl bromide is really strong against weeds," Fennimore said. "When you use them together, there's a synergy. They're very complementary."