A new type of plastic cover that helps stop chemical soil fumigants from escaping into the atmosphere could provide a timely alternative for farmers facing a ban on methyl bromide, according to Agricultural Research Service scientists.
ARS scientists in Gainesville, Fla., are studying plastic covers placed over raised beds where vegetables and strawberries are grown. Fumigants applied to the soil are trapped underground by the plastic, controlling pests under the soil surface.
One type of plastic cover, called virtually impermeable film (VIF), contains a central, gas-impermeable layer designed to curb soil fumigant from escaping into the atmosphere.
ARS is studying environmentally safe alternatives to methyl bromide as a soil fumigant for crop protection. VIF alone isn't intended to serve as a replacement for methyl bromide, according to researchers, but would allow growers to use lower levels of fumigants that are more environmentally friendly than methyl bromide.
Hartwell Allen, a soil scientist at the ARS Center for Medical, Agricultural and Veterinary Entomology's Crop Genetics and Environmental Research Unit in Gainesville, and collaborators at the University of Florida showed that VIF can retain alternative soil fumigants at higher concentrations for longer periods in soil than standard high-density polyethylene film now used in vegetable and strawberry production.
One alternative fumigant the researchers tested was 1,3-dichloropropene (1,3-D). Allen and Joseph Vu, an ARS plant physiologist, and university researchers John Thomas, Li-Tse Ou and Donald Dickson conducted several field trials in sandy soils at Gainesville to compare VIF polyethylene film on raised beds.
They found that VIF retained more active compounds in the fumigants for a longer period of time, provided more uniform distribution of 1,3-D, and slowed surface emissions of the fumigant more effectively. Further development of VIF technology is needed, however, to improve the speed and reliability of its application.
Use of methyl bromide is due to be phased out in developed nations because it was found to deplete the Earth's ozone layer.
ARS is the U.S. Department of Agriculture's chief scientific research agency.