Influence of cropping systems on stem rot (Sclerotium rolfsii), Meloidogyne arenaria, and the nematode antagonist Pasteuria penetrans in peanut

The effect of crop rotation (main plots) and pesticide treatment (subplots) on stem rot (Sclerotium rolfsii), Meloidogyne arenaria, and the nematode a ntagonist Pasteuria penetrans was determined in a field experiment. The fie ld site was naturally infested with all three organisms. Peanut (P) was rot ated with 2 years of either cotton (Ct), corn (C), or bahiagrass (B). The p esticide treatments for the peanut crop were aldicarb (31 g a.i. per 100-m row), flutolanil (1.7 kg a.i./ha), aldicarb + flutolanil, and a control wit hout either pesticide. Populations of M. arenaria were lower in peanut in t he Ct-Ct-P than in P-P-P, C-C-P, or B-B-P plots and tended to be lower in p lots treated with aldicarb. Abundance of P. penetrans endospores was highes t in the P-P-P plots, intermediate in the B-B-P rotations, lowest in all ot her rotations, and was unaffected by aldicarb. The high endospore densities in the P-P-P plots may have contributed to the uncharacteristically low ne matode populations in the monoculture. Incidence of stem rot in peanut was lowest in treatments with flutolanil, intermediate in the control, and high est in treatments with aldicarb alone. The greater canopy cover in aldicarb -treated plots may have created a conducive environment for S. rolfsii infe ction.