Fumigant Alternatives to Methyl Bromide for Polyethylenemulched Tomato

Abstract

Tomato ( Lycopersicon esculentum Mill.) was grown to evaluate various chemicals as possible alternatives to methyl bromide as a soil fumigant. Due to pest pressures from weeds, nematodes, and soil fungi, the use of a broad-spectrum fumigant is essential for economical tomato production. Methyl bromide (MBr) is the fumigant of choice for most growers using polyethylene mulch culture. In 1991, MBr was identified to be in a group of chemicals allegedly responsible for depletion of the stratospheric ozone layer. The U.S. Environmental Protection Agency (EPA) has since called for a phaseout of MBr by the year 2001. At several locations in Florida, alternative soil fumigants were evaluated including 98% MBr-2% chloropicrin (Pic) at 450 kg·ha –1 , 67% MBr 33% –Pic (392 kg·ha –1 ), Pic (390 kg·ha –1 ), 1,3-dichloropropene + 17% Pic (1,3-D+C17) at 327 L·ha –1 , and metham sodium (935 L·ha –1 ). Metham sodium was also applied by drip irrigation as well as enzone (1870 L·ha –1 ). Dazomet (448 kg·ha –1 ) was surface applied and incorporated. Pebulate (4.5 kg·ha –1 ) was incorporated with some treatments. Pic and 1,3-D+C17 treatments provided control of nematodes and soil fungi. With the addition of pebulate, some nutsedge control also was obtained. Tomato fruit yields with 1,3-D+C17 + pebulate and with Pic + pebulate ranged from 86% to 100% of that obtained with MBr treatments. Pest control and crop production were lower with the other treatments than with the above combinations and with MBr. These studies indicate that no one pesticide can provide the broad spectrum control provided by MBr.