HS287 Application Considerations for Successful Use of VIF and Metalized Mulches with Reduced Fumigant Rates in Tomato 1 Bielinski M. Santos, James P. Gilreath, John Mirusso, Joseph W. Noling and Phyllis Gilreath. 2 1. This document is HS287, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 2005. Reviewed November 2010. Revised September 2012. Visit the EDIS website at http://edis.ifas.ul.edu. 2. Bielinski M. Santos, associate professor, Gulf Coast Research and Education Center; James P. Gilreath, professor, Gulf Coast Research and Education Center; John Mirusso, Mirusso Enterprises, Inc., Delray Beach; Joseph W. Noling, professor, Citrus Research and Education Center; Phyllis Gilreath, Extension agent, Florida Cooperative Extension Service, Manatee County, University of Florida, Gainesville, FL 32611. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or ailiations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean Methyl bromide (MBr) alone, or in combination with chloropicrin (Pic), has been the soil fumigant of choice since the early 1970s (Overman and Martin, 1978), because of its ease of use and high eicacy under a wide range of conditions. It is typically shank-injected at 350 lb/ acre to a soil depth of 10 inches into raised beds that are simultaneously covered with LDPE mulch. Standard LDPE is inexpensive and easy to use, but it is highly permeable to MBr (Gamliel et al., 1998a, 1998b; Papiernik and Yates, 2001; Williams et al., 1999; Yates et al., 1996a, 1996b). MBr has been classiied as a substance that contributes to depletion of stratospheric ozone. Consequently, a complete phase-out of the use and production of MBr in developed countries throughout the world was scheduled to occur by 2005, with critical use exemptions permitted under the Montreal Protocol (U.S. Environmental Protection Agency, 1999). Critical use exemptions (CUE) are important for minor crops because growers feel that an economically and technically viable MBr alternative is not yet commercially available. However, even with permitted exemptions, reduced rates of MBr may be needed to ofset the rising cost of the fumigant and to reduce atmospheric emissions. Reduced emissions probably will be a requirement for future CUEs. To obtain a high degree of pest control with a fumigant, it is necessary to maintain a suicient quantity of fumigant gas in the soil long enough to reduce the population of pests (Gamliel et al., 1998b; Minuto et al., 1999). his might be accomplished by using low rates of MBr under highly reten- tive or reduced permeability ilm. Virtually impermeable ilm (VIF) is so named due to the much higher fumigant retention capacity of this ilm compared to ldpe and hdpe, which have been the historical mainstays of plasticulture. VIF has become commercially available in recent years and is much more retentive of fumigant gases than standard ldpe mulch (Papiernik and Yates, 2001). his type of ilm increases fumigant toxicity by increasing the duration of retention, which is caused by a barrier polymer, such as ethylene vinyl alcohol or nylon, placed between two layers of polyethylene (Papiernik and Yates, 2001). Wang et al. (1997) determined that atmospheric emission of MBr, when covered with polyethylene for 5 days, declined from 64% of applied MBr with conventional LDPE mulch to about 38% with VIF. With the soil covered by VIF for more than 10 days, only 1% to 3% of the MBr was lost. In the past six years, considerable ield research and grower trials have been conducted with these VIF mulches in Florida. Small plot studies demonstrated that nutsedge and stunt nematodes could be controlled and crop yields