ALTERNATIVE FUMIGANTS FOR METHYL-BROMIDE IN TOBACCO AND PEPPER TRANSPLANT PRODUCTION

Tobacco and pepper are high-value cash crops in the southeastern USA t hat require vigorous transplants free of pathogens and insects. Typica lly soil seedbeds are treated with methyl bromide prior to seeding. So il fumigants metam-sodium, dichloropropene, chloropicrin and dazomet c overed with polyethylene film were evaluated at several rates alone an d in combination as alternatives for methyl bromide soil fumigation of tobacco and pepper seedbeds. The studies were conducted over a three- year period, with materials applied in the fall prior to seeding at th e beginning of the following year. Nematode and insect pressures were low in each of three sites, but the tests extensively evaluated weeds and soilborne fungi management. Metam-sodium at 935 L ha(-1) performed well in all three tests. The combination of metam-sodium (468 L ha(-1 )) plus dichloropropene+17% chloropicrin (126 L ha(-1)) provided good control of most of the pests and had high plant yield and vigor when c overed with a polyethylene film immediately after treatment. A similar treatment not covered with polyethylene film but sealed with a mechan ical soil cultipacker provided poor control of weeds. Stunting of toba cco and pepper was noted, especially in plots treated at the highest r ates of metam-sodium plus dichloropropene and chloropicrin. These trea tments had a pungent odor associated with the treatment, which persist ed for several weeks after polyethylene film removal. Many of the trea tments, especially metam-sodium and metam-sodium in combination with d ichloropropene and chloropicrin, compared well with methyl bromide fum igation for seedbed pest control. (C) 1997 Elsevier Science Ltd.