Effectiveness of broadcast application of Telone C-35 and Tillam + Devrinol in tomato

Two experiments (Fall 2000 and Spring 2001) were conducted to determine the efficacy of broadcast applications of a mixture of 65% 1,3-dichloropropene (Telone II) and 35% chloropicrin (Telone C-35) with a tank mix of pebulate (Tillam) + napropamide (Devrinol) herbicides. These treatments were compared to in-bed applications of Telone C-35 as an alternative to methyl bromide for soil fumigation in fresh market tomato production on flatwoods soils in west central Florida. Treatments consisted of a nontreated control, Telone C-35 applied in-bed, Telone C-35 applied broadcast with a Yetter Avenger coulter applicator, alone or followed by additional chloropicrin applied in-bed, Telone II broadcast followed by additional chloropicrin in the bed, and methyl bromide in-bed. A tank mix of Tillam + Devrinol was applied broadcast and incorporated in the top 5 to 6 inches of the soil in both experiments prior to bed formation. Treatments were located on the same site each season to allow pest populations to build over time as a result of seasonal treatments. Staked tomatoes were grown on polyethylene mulched beds and data were collected for control of nutsedge, soilborne diseases and nematodes, and tomato fruit production. There was little nutsedge in the test site in the fall, but by the spring the population had increased and treatment differences were observed. Although all Telone plots were treated with Tillam + Devrinol for nutsedge control, Telone C-35 in-bed was more efficacious than broadcast application, unless chloropicrin was applied to the bed. Soilborne disease (Southern blight and Fusarium wilt race 3) control varied somewhat between broadcast and in-bed application of Telone C-35. Fusarium wilt was more prevalent in the fall and was controlled by all fumigant treatments. There was no difference in wilt incidence the spring. Southern blight was not a serious pest in the fall but by spring it had become better established. While in-bed application of Telone C-35 provided blight control equal to the methyl bromide in the spring, broadcast application did not, unless it was accompanied by additional chloropicrin in the bed. Telone controlled nematodes regardless of the method of application. Tomato yields followed the same trend as nutmedge and southern blight control; marketable fruit yields were not different among fumigant treatments in the fall, but in the spring yield was lower where Telone C-35 was applied broadcast without additional chloropicrin applied to the bed.