Verticillium wilt of tobacco

Abstract Eight newly introduced tobacco cultivars were screened for resistance to Verticillium dahliae Kleb. in 1965–6 season, and the following year 10 cultivars and four advanced breeding lines were tested for resistance. The mode of inheritance of resistance found in four of the cultivars used in the breeding programme was studied in a set of diallel crosses. Most of the genetic variance appeared to be controlled by additive factors, with the high level of resistance found in a biotype of McNairs 121 conditioned by polygenes. However, in the field-tolerant cultivar Coker 187 Hicks, most of the resistance was the result of epistatic effects.