EFFECTS OF TROPICAL ROTATION CROPS ON MELOIDOGYNE-ARENARIA POPULATION-DENSITIES AND VEGETABLE YIELDS IN MICROPLOTS

The effects of 12 summer crop rotation treatments on population densit ies of Meloidogyne arenaria race 1 and on yields of subsequent spring vegetable crops were determined in microplots. The crop sequence was: (i) rotation crops during summer 1991; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) squash (Cucurbita pepo) during s pring 1992; (iv) rotation crops during summer 1992; (v) rye during win ter 1992-93; (vi) eggplant (Solanum melongena) during spring 1993. The 12 rotation treatments were castor (Ricinus communis), cotton (Gossyp ium hirsutum), velvetbean (Mucuna deeringiana), crotalaria (Crotalaria spectabilis), fallow, hairy indigo (Indigofera hirsuta), American joi ntvetch (Aeschynomene americana), sorghum-sudangrass (Sorghum bicolor x S. sudanense), soybean (Glycine max), horsebean (Canavalia ensiformi s), sesame (Sesamum indicum), and peanut (Arachis hypogaea). Compared to peanut, the first eight rotation treatments resulted in lower (P le ss-than-or-equal-to 0.05) numbers of M. arenaria juveniles on most sam pling dates. Soybean, horsebean, and sesame rotations were less effect ive in suppressing nematodes. Yield of squash was greater (P less-than -or-equal-to 0.05) following castor, cotton, velvetbean, and crotalari a than following peanut. Compared to the peanut rotation, yield of egg plant was enhanced (P less-than-or-equal-to 0.10) following castor, cr otalaria, hairy indigo, American jointvetch, and sorghum-sudangrass. S everal of these rotation crops may provide a means for depressing M. a renaria population densities on a short-term basis to enhance yields i n a subsequent susceptible vegetable crop.