Effects of Nematicides and a Moderately Resistant Cultivar on Root-Knot Nematode Control in Cotton

N.R. Benson, T.L. Kirkpatrick, and K.F. Martin


Approximately 30% of the 200,000 acres of cotton in Mississippi County, AR, are infested with Meloidogyne incognita. In many areas the nematodes are involved in significant yield reductions. A series of field evaluations were initiated in 1993 to determine the effects of including a cotton cultivar with moderate resistance to M. incognita and a nematicide into cotton management programs. The site was near Wilson, AR, in a field with a history of nematode problems. Cotton cultivars used were Stoneville 825 (S825), susceptible to M. incognita and Stoneville LA 887 (LA887) moderately resistant. Aldicarb (Temik 15 G) and fenamiphos (Nemacur 15 G) were applied to S825 at rates ranging from 3.5 lb/acre to 7.0 lb/acre in furrow at planting. With LA887 Temik was applied at 3.5 and 5.0 lb/acre and Nemacur was applied at 5.0 lb/acre. Nematode population densities at planting were not significantly different among plots with preplant densities ranging from 106-280 juveniles/500 cm3 soil. At harvest all treatments that included S825 cotton had significantly higher nematode population densities than treatments that included LA887. Root gall index was significantly lower on LA887 plants than on S825 plants for all treatments. Application of nematicides, regardless of rate or nematicide used did not significantly lower root galling index in comparison with the untreated control for either cultivar. In addition, vascular discoloration due to Fusarium oxysporum f. sp. vasinfectum was significantly lower in LA887. Although all nematicide treatments improved seedcotton yield of S825 in comparison with the untreated control, application of nematicides did not result in seedcotton yields for S825 that was equivalent to the yield of LA887. Nematicide application to LA887 resulted in a slight increase in seedcotton yield in comparison to the untreated control, but this increase was not significant for any nematicide treatment.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 278
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998