Economic Returns in Plasticulture Tomato Production from Crucifer Cover Crops as a Methyl Bromide Alternative for Weed Management

The phase-out of methyl bromide required an effective and economically viable alternative for weed management in polyethylene-mulched tomato (Solanum lycopersicum). A field experiment was conducted to compare economics of tomato production associated with crucifer (Brassicaceae) cover crops under low-density polyethylene mulch (LDPE) and virtually impermeable film (VIF) mulch with a standard treatment of methyl bromide:chloropicrin (67:33) at 350 lb/acre. Three crucifer cover crops, 'Seventop' turnip (Brassica rapa), 'Pacific Gold' oriental mustard (Brassica juncea), and Caliente [a blend of brown mustard (B. juncea) and white mustard (Sinapis alba)] were evaluated in combination with hand-weeding. Because of marginal weed control from crucifer cover crops, hand-weeding cost in all cover crop plots, regardless of mulch type, increased from $380.54/acre to $489.10/acre over that in methyl bromide plots. However, total weed management costs in the untreated control and cover crops with LDPE treatments were $17.82/acre to $111.33/acre lower than methyl bromide. Because of mulch expenses, VIE mulch increased the total weed management cost by $328.16/acre over LDPE mulch in the untreated control and cover crop treatments. Because of equivalent marketable yield, gross returns ($21,040.43/acre) were identical in all treatments. Preplant fumigation with methyl bromide provided $6260.90/acre of net returns in tomato production. The untreated control, 'Seventop' turnip, 'Pacific Gold' oriental mustard, and Caliente mustard under LDPE treatment were $54/acre, $54/acre, $98/acre, and $147/acre more profitable, respectively, than methyl bromide. However, in all other treatments under VIE, net returns relative to methyl bromide were reduced from $181/acre to $274/acre. Therefore, regardless of soil amendment with crucifer cover crops, hand-weeding can serve as an economically viable alternative to methyl bromide for weed control in LDPE-mulched tomato production, depending on the nature and level of pest infestation, labor availability, and wages.