other fields that have not been used for two or three years, thus reducing the incidence of those

pests that negatively affect the crop (Bewick, 1989).

 Due to increased competition in Florida for agricultural land by urban development and

 environmental pressures, increased land prices and decreased land availability have resulted in

 farmers searching for alternative methods of pests control (Bewick, 1989). According to

 Johnson and Feldmesser (1987), the first use of a fumigant may have been as early as 1872

 where experiments proved the efficacy of carbon disulfide as a nematicide. Carbon disulfide

 was used in grape production in France, however, it was discontinued due to the development

 of pest resistant rootstocks. Chloropicrin was first tested as a soil fumigant in 1919. Research

 was then initiated in California and Hawaii. Later it was used as a soil fumigant in pineapple

 production in Hawaii. Large quantities of chloropicrin were made available by the United States

 government and were targeted for use in seed beds, greenhouses, and specialty crops. When

 supplies diminished, commercial use of this chemical decreased.

 A marked increase in research on the use and efficacy of soil sterilants was conducted

during the 1950's. During this time, it was found that methyl bromide and chloropicrin gave

the most effective, consistent control of soilborne pathogens (Williamson et. al. 1955).

 Research on application methods during the 1960's found that the use of vinyl or

polyethylene films, applied after soil injection of methyl bromide, increased pest control

efficacy. In 1965, Geraldson et al. (1965) introduced the raised bed, methyl bromide, plastic

mulch culture to Florida tomato producers (Bewick, 1989). The use of plastic mulch also

proved to reduce leaching of fertilizers, to retain soil moisture and to increase weed control over

a longer period of time (Martinkovic and Nesheim, 1993). However, system complexity and

the time and expense involved in field removal of plastic mulch resulted in slow adoption of this

technique during the early 1960's.