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<ol> <LI> To evaluate differences in pest control efficacy and crop growth of methyl bromide and other next best fumigant chemical alternatives in large, commercial scale, field demonstration trials in west central Florida strawberry crops. <LI> To evaluate and compare, in grower field demonstration trials a diversity of commercial high barrier / gas impermeable (VIF) mulch films with regard to a) physical and mechanical properties, film permeability, labor needs and tractor speeds required for field installation; b) soil diffusion and retention characteristics of fumigant gases under different soil moisture and tillage regimes; c) abilities to reduce soil fumigant emissions and field application rates; d) and to compare crop yield and pest control efficacy of alternatives to that of methyl bromide. <LI> To measure differences in soil fumigant concentration and retention among the different mulches, tillage practices, and along increasing gradients of soil moisture. <LI> To develop and extend comprehensive In-Service Training programs for county Cooperative Extension agents and educational programs for principal stakeholders regarding methyl bromide alternatives research, alternative fumigants, impacts of irrigation, tillage, and gas impermeable plastic mulch technologies in the formulation of transition strategies away from methyl bromide use.
Non-Technical Summary: Environmental problems with the soil fumigant methyl bromide, coupled with the continued reliance of growers on existing and internationally approved supplies, have led to the urgent need to implement alternative methods for managing soilborne nematodes, weeds, and disease problems into the farming practices of Florida strawberry growers. With the depletion of existing supplies and diminishing levels of approved levels within critical use exemptions (CUE) for methyl bromide, large scale grower field trials are needed to demonstrate the efficacy and economics of alternative methods of weed, nematode, and disease control. Alternative chemicals to be evaluated include individual and or combined use of chloropicrin, 1, 3-dichloropropene, and or metham sodium, with use of appropriate herbicide(s). Field evaluation of iodomethane (methyl iodide) will also be considered, contingent upon continued product registration status and federal regulatory approval. Plot sizes for each alternative chemical treatment will be a total of 1 acre MOL, being compared to a grower standard treatment of methyl bromide chloropicrin (67/33; 350 lb/a), using low density polyethylene mulch. Treatment evaluations will also include reduced fumigant use rates and other emission reduction strategies including comparisons of commercial high barrier, gas impermeable (VIF) plastic mulches. The project will also focus on the importance of traffic pans (soil compacted zones) as impediments to downward movement of soil fumigants and as a contributing cause to pest control inconsistencies. Additional studies, which evaluate prefumigation soil moisture conditions, will also be conducted to ascertain contributions to pest control inconsistencies with soil fumigants and suboptimal moisture condition. The project also focuses on the development of educational programs for principal stakeholders regarding methyl bromide alternatives research and formulation of transition strategies away from methyl bromide use. Principal outcomes involve seemless transitiions for Florida strawberry growers in terms of sustained yields and pest control consistencies. <P> Approach: Grower field demonstration trials will be conducted in commercial strawberry fields of west central Florida. Treatments for each grower trial will include methyl bromide/chloropicrin (67/33; 350 lb/a) as the standard for comparison with that of an alternative chemical treatment regime. At least two fumigant alternative treatments from a recommended list will be evaluated in at least 3 field replicated strips. A principal focus of these studies involves the evaluation of high barrier / VIF mulches, coupled with reduced in-row applications of 1,3-D and Chloropicrin (as Telone C35 (15-20 gpa) or Telone InLine (15-20 gpa./ Actual methods of soil application of methyl bromide, chloropicrin, and other alternatives chemicals will vary depending upon experimental objectives, new field research results, and by grower demands. With a high barrier / VIF mulch, rate reduction of at least 50 to 75% of maximum label rate will be evaluated in each field trial. The following day after soil fumigation, replicate soil gas concentration measurements will be acquired from two locations of four mulch covered plant beds within each of the replicate strips of each fumigant mulch treatment. Fumigant gas concentrations at a 6 inch soil depth soil depth will be measured at the bed center twice weekly (3-4 day basis) with a MiniRAE 2000, portable VOC meter, referenced to isobutylene, until near complete disappearance of all fumigants occur.