The efficacy of metam sodium (sodium N-methyl dithiocarbamate), a methyl isothiocyanate (MITC) generator, was evaluated in a laboratory dose-response study to control major weeds, pathogenic fungi, and parasitic nematodes in California soils. A sandy loam soil (14% water content, wt/wt), highly infested with Verticillium dahliae, and Pythium ultimum was placed into 250 mL jars. Bags containing soil infested with Phytophthora cactorum, citrus nematodes, and imbibed seeds of Cyperus esculentus, Kochia scoparia, Malva priviflora, Portulaca oleracea, Stellaria media, and Polygonum arenastrum were placed in mash bags at 2.5 to 4.0 cm below the soil top. The jars were capped and metam sodium was applied with water through a septa using an air-tight syringe to achieve final concentrations of 0, 10, 25, 50, 75, 100, 125, 250, 500, 750, 1000, 1250, and 2500 uM L^-1, corresponding to field application rates of 0 to 80 gal Sectagon ac^-1. After incubation at 10 and 20^oC for 24 h, the soil, and bags with Phytophthora, citrus nematodes, and weed seeds were ventilated under a sterile laminar fume hood. Metam sodium concentrations greater than 750 uM L^-1 at room temperature controlled most weed seeds, pathogenic fungi, and citrus nematodes. Metam sodium concentrations required to reduce seed, pathogen, and nematode viability by 50 (LD₅₀) and 90 percent (LD₉₀) after a 24 h exposure time at 10 and 20^oC for six major weeds, three important soil-borne fungal pathogens, and parasitic nematodes will be presented.