Rotylenchulus reniformis Linford & Oliveira is increasing in incidence in cotton-growing areas throughout the southern USA east of New Mexico. Cotton (Gossypium hirsutum L.) cultivars resistant to R. reniformis are currently unavailable. Management depends on a crop sequence with nonhosts of the nematode. In South Texas, the sequence of cotton with grain sorghum [ Sorghum bicolor (L.) Moench] or corn ( Zea mays L.) has become a standard practice. To improve farm efficiency, the implementation of rotation crops that are economically superior to grain sorghum is desirable. Eighteen cultivars of soybean [ Glycine max (L.) Merr.] were tested in nonfumigated and in fumigated sandy loam soil infested with R. reniformis to evaluate nematode resistance of soybean under field conditions. Shank application of 1,3-dichloropropene at a 38-cm depth reduced R. reniformis population densities at the 15- to 60-cm depth compared with preseason counts. The effect of each soybean cultivar on the growth and yield of a subsequent cotton crop was compared with the impact of grain sorghum and fallow. High-yielding cultivars of soybean (HY574, Padre, DP7375RR, and NK83-30) with reniform nematode-suppressing potential were identified among cultivars within maturity groups 5, 6, 7, and 8. In contrast, cotton yields following the susceptible cultivars Santa Rosa-R, Vernal, and DP6880RR were on average 25% lower than those following grain sorghum. The enrichment of cotton sequences with reniform nematode-resistant soybean cultivars is viable when the proper cultivars are chosen, whereas the use of reniform nematode-susceptible soybean cultivars is discouraged. The effective use of R. reniformis-resistant soybean cultivars to manage R. reniformis in cotton will depend on a number of additional economic parameters not studied in these experiments.
