A Clovelly soil in Tala Valley (Natal) was fumigated with different concentrations of dazomet (300, 400, 500 kg ha−1) (granular formulation), and metham sodium (500, 750, 1000 L ha−1) (liquid formulation). Half the treatments were covered with plastic sheets during fumigation. After fumigation weed germination was rated and soil analysed for parasitic nematodes. The trial site was planted with‘Robinvale’lettuce seedlings. Dazomet was more effective than metham sodium in decreasing weed germination and efficacy of both chemicals was improved by covering the sites with plastic.Meloidogyne(root-knot nematode) andTrichodorus(stubby root nematode) were present prior to fumigation but their levels were reduced by dazomet. Nematode control by metham sodium was inconsistent and not improved by higher concentrations of fumigant. Nematode populations were counted again at harvest from both soil and root samples. These results were variable and could not be directly related to treatments. Dazomet significantly increased lettuce yields from 81 ha−1(control) to 44 t ha−1(500 kg ha−1dazomet). Fumigation with metham sodium and covering with plastic sheets did not significantly improve yields.