The performance of select genotypes of peanut to natural inocula of Cylindrocladium black rot and tomato spotted wilt virus in Florida

Cylindrocladium black rot (CBR), caused by the fungus, Cylindrocladium parasiticum Crous, Winpfield, & Alfenas (teleomorph Calonectria ilicicola Boedijin & Reitsma), has become a major problem for some peanut producers in Florida. Growers have relied upon a fungicide spray program with tebuconazole H-1,2,4-triazole-1-ethanol proportional to-[2-(4-chlorophenyl)ethyl]-proportional to (1,1-dimethyl) for CBR, but that requires added expense. The possibility that existing cultivars might have some levels of resistance to CBR was investigated. In field tests in 1996 and 1997, 'Southern Runner', 'Georgia Green', and 'Florida MDR 98' had significantly lower levels of CBR than other cultivars. Georgia Green and Florida MDR 98 were further examined in 1998, and the rates of disease progress and areas under their disease progress curves cc ere significantly lower than for 'Florunner'. In 1997, one breeding line, 90 x 7-15-1-b2-B, tvas found to possess resistance to CBR. In a test in 1998 for CBR, only tomato spotted wilt virus (TSWV) occurred at the test site, and this same breeding line expressed resistance to this viral disease. It now appears that we can use resistance to offset damage from CBR, and with some genotypes expressing resistance to both CBR and TSWV, additional benefits for die grower appear to be available.