Strawberry trials seek long-term economic methyl bromide replacements
By Vicky Boyd
Four soil fumigants all appear to work well in strawberry fields that have been historically treated with methyl bromide to suppress soil-borne diseases, weeds and nematodes.
What remains unknown is how they will work in four to five years when the residual effects of methyl bromide have worn off and soil-borne pest populations have begun to climb, says Shawn Crocker, executive director of the Plant City-based Florida Strawberry Growers Association.
“That’s really the million dollar question,” Crocker says. “A lot of these products work really well here after methyl bromide because the [pest] populations of hardened seed and disease have been reduced. Three to five years is when these products will really start to show whether they provide control because they are not following methyl bromide anymore.”
Crocker is in the second year of a large-scale field trial at the association’s Plant City facility comparing four fumigants with methyl bromide, which has been the grower standard for decades.
The 1987 Montreal Protocol changed that by classifying methyl bromide an ozone-depleting chemical and developing a phase-out for its use. The international treat required developed countries to cease production and use of the fumigant by 2005, whereas developing countries have until 2010 to completely phase out its use.
In both cases, the protocol allows for critical-use exemptions should alternative not be available. U.S. growers, including the strawberry industry, have successfully petitioned for critical-use exemptions the past three seasons.
In search of the Holy Grail
The Florida strawberry trials are part of a continuing effort within agriculture to find viable replacements for the widely used fumigant.
Crocker has five replicates on the 10-acre parcel near Dover, Fla. Although his trial involves a mixture of 98 percent methyl bromide and 2 percent chloropicrin, some growers have resorted to 67-33 (67 percent methyl bromide and 33 percent chloropicrin) since the 98-2 is more difficult to find.
He also is overseeing five trials in growers’ fields comparing methyl bromide to a 50-50 blend of methyl iodide and chloropicrin, marketed as Midas by Arysta LifeScience Corp. of Cary, N.C.
Midas has been used under a non-crop-destruct experimental use permit in Florida, Georgia, Michigan, North Carolina, South Carolina and Virginia since 2006. About 1,000 acres are involved.