Methyl Bromide Alternatives for Vegetable Production In Georgia: Small-Plot Trials

In Georgia, the loss of MeBr directly impacts the production and profitability of several fruiting vegetables [specifically, pepper (Capsicum annuum L.), eggplant (Solanum melogena L.), and tomato (Lycopersicum esculentum Mill)) and cucurbits (specifically, squash [yellow (Cucurbita pepo L.)], melons [watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai) and cantaloupe (Cucumis melo L.)], and cucumbers (Cucumis sativus L.). Combined, these crops have a farm gate value of more than $400 million. Between 2004 and 2008, we evaluated the effects of MB, methyl iodide (MIDAS), Telone II plus chloropicrin (T2+Pic), Telone II plus chloropicrin in rotation with MB (T2+Pic/MB), Vapam (metam sodium), Telone II plus chloropicrin plus Vapam (3-Way), and Telone C35 (T-C35), with and without herbicides, on weed densities in spring planted bell pepper. Weed pressure (nutsedges, annual grasses and pigweeds) was significantly influenced by fumigant, herbicide and the interaction between the main effects. Nutsedges were present at the beginning of the study at a density of less than 1 plant per meter squared. By 2008, nutsedge densities in the Vapam, T-C35, NF, and T2+Pic treatments averaged between 1.5 and 13.4 plants per meter squared (up to 134,000 plants per hectare). The use of herbicides (clomazone, S-metolachlor and napropamide) reduced nutsedge numbers in these plots more than 46% as compared to a non-fumigated, non herbicide control. Like the nutsedges, crabgrass and pigweed densities were also greatest in the T-C35, NF, T2+Pic plots when herbicides were not applied. Nutsedge, crabgrass, and pigweed populations did not increase over time in the MB, MIDAS, T2+Pic/MB, and 3-Way systems. If cost effective, the MIDAS and 3-Way alternative fumigation systems are the best for managing weed population densities over time.