Six multiple-cropping systems composed of: a) turnip (Brassica campestris spp. rapifera), corn (Zea mays L.), and snapbean (Phaseolus vulgaris L.); b) turnip, peanut (Arachis hypogaea L.), and snapbean; c) turnip, corn, and turnip; d) turnip, peanut, and turnip; e) snapbean, soybean [Glycine max (L.) Merr.], and cabbage (Brassica oleracea L.); and f) turnip, cucumber (Cucumis sativus L.), cowpea [Vigna unguiculata (L.) Walp.], and turnip were subjected to nematicide and weed control programs of cultivation or herbicides. Herbicide programs were superior to cultivation in control of weeds. Weeds remaining in the row following cultivation competed severely with crops. Weed species remaining were altered depending on the method of control and crop. Yellow nutsedge (Cyperus esculentus L. ♯3 CYPES) increased rapidly in all herbicide programs but not in cultivated plots. Pigweeds (Amaranthus spp.) were controlled by herbicides but increased in cultivated plots. Corn, peanut, soybean, and spring snapbean yields were higher in herbicide treatments than in cultivated treatments. Cucumber was the only crop that had increased yields for both main effects, herbicide and nematicide. Turnip was consistently injured in herbicide treatments, which was believed to be caused by residues from previous crops interacting with pathogens and possible allelopathic effects of decaying organic matter.