SUPPRESSION OF FOLIAR AND SOILBORNE PEANUT DISEASES IN BAHIAGRASS ROTATIONS

Florunner peanut was grown after 1, 2, or 3 years of Tifton 9 bahiagra ss and in alternating years with bahiagrass. Continuous peanut was gro wn in nontreated plots and in plots treated with flutolanil (4.48 kg/ ha). In continuous peanut, stem rot (Sclerolium rolfsii) incidence was 4, 18, 19, and 44% during 1990 to 1993, respectively, without flutola nil and 0, 4, 10, and 17% with flutolanil. In 1993, stem rot incidence was 39, 29, 17, and 23% in the third, second, first, and alternating year of peanut, respectively. Rhizoctonia limb rot severity was low to moderate and not affected by crop rotation. Leaf spot diseases caused by Cercospora arachidicola and Cercosporidium personatum were present each year and were more severe in the short-term rotations. Pod yield of peanut was 3,044, 3,616, 4,547, and 3,922 kg/ha during the third, second, first, and alternating year of peanut respectively. Compared t o continuous peanut, longer rotations or treatment with flutolanil inc reased peanut grades and reduced percent damaged kernels (seeds). Popu lation densities of Rhizoctonia solani and Pythium spp. in the soil ge nerally were low and not altered by crop rotation. Rotation had little effect on root-knot (Meloidogyne incognita), ring (Criconemoides curv atum), or lesion (Pratylenchus brachyurus) nematodes.