Stetina, S. R., L. D. Young, W. T. Pettigrew, and H. A. Bruns. 2007. Effect of Corn-Cotton Rotations on Reniform Nematode Populations and Crop Yield. Nematropica 37:237-248. Corn (Zea mays) as a rotation crop with cotton (Gossypium hirsutum) was evaluated in a field study conducted from 2000 through 2003 at Stoneville, MS to determine its effect on reniform nematode (Rotylenchulus reniformis) population density. The experimental design was a randomized block splitplot with eight replications. The main plots were crop rotations (continuous cotton, continuous corn, corn-cotton-corn-cotton, or cotton-corn-corn-cotton), and six-row subplots were one of four genotypes of either corn or cotton. Nematode populations in the center two rows of each subplot were determined at planting, midseason, and harvest. Cotton and corn yields were determined from samples taken from one or all four of the inner subplot rows, respectively. In plots planted to cotton the previous season, nematode populations at planting exceeded damaging levels for Mississippi, regardless of rotation sequence. Nematode populations remained below damaging levels throughout the season in cotton following two seasons of corn. However, when cotton followed one season of corn, nematode populations rebounded to damaging levels by the end of the season. Cotton lint yield from the cotton-corn-corn-cotton rotation was 194 kg/ha greater than yield from the continuous cotton plots in 2003. At the nematode population levels in this study, a rotation with at least two consecutive years of corn appears to be necessary to achieve reniform nematode suppression sufficient to increase cotton yield. Corn yields were either not affected or, in one year, improved when the crop was grown in rotation with cotton. Crop genotype did not affect reniform nematode population density, and there were no genotype x rotation interactions with respect to either reniform nematode population density or crop yield.
