Influence of Nematicide Application on the Severity of the Root-Knot Nematode-Fusarium Wilt Disease Complex in Cotton.

Eight cotton cultivars, with and without aldicarb treatment, were evaluated for their effect on the severity of the root-knot nematode-Fusarium wilt disease complex in cotton. A randomized complete block design with a split-plot arrangement of treatments was used with cotton cultivars as the main plots and nematicide treatments as the subplots. Results in 1994 and 1995 were similar. Yield of lint, boll weight, and wilt and root-gall ratings were different among cultivars and between nematicide treatments both years. Increased lint yield and boll weight, and reduced root-gall and wilt ratings were associated with application of aldicarb. Increased lint percentage was associated with application of aldicarb in 1994, but not in 1995. Fiber micronaire, elongation, uniformity, and strength were different among cultivars, but not between nematicide treatments. Fiber length (UHM; Upper-Half Mean) was different among cultivars and was higher in the aldicarb-treated plots in both years. Numbers of Meloidogyne incognita second stage juveniles and eggs extracted from soil samples were lower in the aldicarb-treated plots in July, but not at harvest, both years. Population densities of M. incognita were not different among cultivars, except the mid-season sample in 1995.