By Meghan Rosen
Earlier this year, California became one of 48 states to legally allow the sale and use of the fumigant pesticide methyl iodide. Methyl iodide is the proposed replacement for methyl bromide, a chemical widely used in California’s production of conventional strawberries. (If you’ve ever driven by fields with rows and rows of tightly stretched black tarps, you may have already seen the fumigation process at work: a few weeks before planting, methyl bromide is pumped into the soil and sealed in with thick plastic sheets. It’s colorless, odorless, and highly toxic; within days the gas can wipe out thriving populations of microorganisms, insects, and weeds — effectively sterilizing the soil.)
As the nation’s largest producer of strawberries (nearly 90% are grown in California), any decision to overhaul pest control is big, time-consuming, and subject to massive environmental and toxicological review. So, why the switch? According to the EPA, methyl bromide is a significant ozone depleting substance. In California, where nearly 40,000 acres are devoted solely to strawberry growth (only 4% is organic) and ~200 pounds of methyl bromide are applied per acre, the potential for environmental impact is huge. (The EPA estimates that 50-95% of the noxious gas escapes during fumigation or is released into the environment when the plastic tarps are removed.)
In 1988, the United States ratified the Montreal Protocol, an international treaty intended to curb use of ozone-depleting substances like methyl bromide. One goal was to completely phase out methyl bromide by 2005, with the exception of ‘critical use exemptions’ for farmers who absolutely depended on the chemical for pest control.

