EVALUATION OF COTTON CULTIVARS FOR RESISTANCE AND TOLERANCE TO ROTYLENCHULUS RENIFORMIS

Abstract

Transgenic and conventional cotton cultivars were examined in the greenhouse and two field locations for resistance and tolerance to R. reniformis. Greenhouse evaluations of 52 cotton cultivars found all cotton cultivars tested were susceptible to R. reniformis. Reproductive factors (Rf) ranged from a high of 59.4 to a low of 4.1. The cultivars SG 105, DP 543 BGII/RR, DP 445BG/RR, and FM 989 R exhibited the lowest 5% of the Rf values. Selected cotton cultivars were evaluated for tolerance to the reniform nematode in both north and south R. reniformis infested areas of Alabama. None of the cultivars evaluated were found to be tolerant to R. reniformis and able to maintain yield potential in northern AL. In southern AL, ST 4793 R and SG 521 R exhibited greater or equal yields between fumigated and non-fumigated plots; however, neither cultivar was consistently tolerant to R. reniformis in northern AL. Results of greenhouse and field testing indicate resistance and consistent tolerance to R. reniformis is not currently available. Although there is no consistent tolerance to R. reniformis, a high yielding variety suited to the area of production can aid in increased yields in the presence of R. reniformis. Results from northern and southern locations in Alabama indicated that cultivars such as DP 451 BR and FM 991 BR, which are intolerant to R. reniformis, can be of economic value if nematicides are not implemented.