Volatilization of 1,3-dichloropropene in Florida plasticulture and effectson fall squash production

One of the proposed alternative chemicals for methyl bromide is 1,3-D. The most common forms of 1,3-D products are cis- or trans-isomers of 1,3-D with the fungicidal agent, chloropicrin, containing such mixtures as 65% 1,3-D and 35% chloropicrin (C-35). Soil fumigants are commonly applied under a po lyethylene film in Florida raised bed vegetable production. Much of the res earch regarding cropping system effects of alternative fumigants to methyl bromide has focused primarily on plant growth parameters, with little regar d to the atmospheric fate of these chemicals. The objective of this researc h was to determine both the atmospheric emission of 1,3-D under different p lastic film treatments and to evaluate effects of application rates of 1,3- D and C-35 on plant pests, growth, and yield of Sunex 9602 summer squash (C ucurbita pepo L.). Results showed that use of a high barrier polyethylene N m (or virtually impermeable film - VIF) greatly reduced fumigant emission c ompared to ground cover with conventional polyethylene films or uncovered s oil. Summer squash seedling survival was a severe problem in several of the 1,3-D alone treatments where no fungicidal agent was added, whereas C-35 r esulted in excellent disease control at both full and one-half of the recom mended application rates for this chemical. Both 1,3-D and C-35 provided go od plant stands and higher yields when applied at their recommended applica tion rates. However, all squash yields were lower than typical squash produ ction levels due to late planting and early winter frost kill. Chemical nam es used: 1,3-dichloropropene (1,3-D); trichloronitropropene (chloropicrin).