Cotton as a Rotation Crop for the Management of Meloidogyne arenaria and Sclerotium rolfsii in Peanut.

The value of cotton (Gossypium hirsutum cv. Deltapine 90) in rotation with peanut (Arachis hypogaea cv. Florunner) for the management of root-knot nematode (Meloidogyne arenaria) and southern blight (Sclerotium rolfsii) was studied for 6 years in a field at the Wiregrass Substation in southeast Alabama. Peanut yields following either 1 or 2 years of cotton (C-P and C-C-P, respectively) were higher than those of peanut monoculture without nematicide [P(-)]. At-plant application of aldicarb to continuous peanut [P(+)] averaged 22.1% higher yields than those for P(-) over the 6 years of the study. The use of aldicarb in cotton and peanut in the C-C-P rotations increased yields of both crops over the same rotations without the nematicide. When the nematicide was applied to both crops in the C-P rotation, peanut yields were increased in only two of the possible three years when peanut was planted. Application of aldicarb to cotton only in the C-P rotation did not improve peanut yields over those obtained with the rotation without nematicide. Juvenile populations of M. arenaria determined at peanut-harvest time were lowest in plots with cotton. Plots with C-P or C-C-P had lower populations of the nematode than those with either P(-) or P(+). The incidence of southern blight (Sclerotium rolfsii) in peanut was lower in plots with the rotations than in those with peanut monoculture. Aldicarb application had no effect on the occurrence of southern blight.