CROP-ROTATION AND NEMATICIDE EFFECTS ON THE FREQUENCY OF MELOIDOGYNE SPP IN A MIXED POPULATION

The effects of crop rotation and nematicide 1,3-dichloropropene (1,3-D) on the relative frequency of M. incognita race 3 and M. arenaria race 2 and on tobacco yields were determined in a sandy loam soil. Cropping sequences altered the species composition and population densities of Meloidogyne spp. and increased tobacco yields. M. incognita predominated when cotton or corn preceded tobacco; M. arenaria predominated when soybean or peanut preceded tobacco. Fumigation of tobacco land increased the density of M. arenaria compared to M. incognita. The effects of a previous crop on tobacco yields varied in successive years. Cotton, corn, peanut, sorghum, or rye-fallow preceding tobacco in 1985 enhanced yields compared to yields when soybean preceded tobacco. Rye-fallow preceding tobacco in 1987 resulted in greater tobacco yields than when tobacco was preceded by soybean, corn, cotton, sorghum or peanut. Application of 1,3-D increased tobacco yields, except when preceded by rye-fallow,