California Strawberries and Methyl Bromide
Currently, some California strawberries can still be treated with MB under a critical use exemption subject to annual review by the parties of the Montreal Protocol. However, MB costs have been increasing and use in strawberry production has been decreasing (CADPR 2011).
Alternative fumigants used in California strawberries are 1, 3-dichloropropene (1,3-D), chloropicrin (Pic) and as of December 2010, methyl iodide. Traditional fumigation in California strawberry dating back to the 1960’s used MB plus Pic applied to the total field area, i.e., “flat fumigation”, where the entire field is covered with polyethylene film to hold the fumigant at the concentration needed to kill soil pests (Wilhelm and Paulus 1980). More recently a sizeable portion of the strawberry acreage is treated with fumigants applied to the strawberry bed via the drip irrigation system (Ajwa et al. 2002; USDS 2009).
Increasingly the public has shown less and less tolerance to fumigant exposure, and regulators have been forced to look for solutions that meet the demands of the public, yet allow farmers to farm. One strategy to reduce potential for fumigant exposure is the use of barrier films which trap the fumigant in the field at the application site.