Abstract

Field trials of 15 cultivars and 15 segregating families revealed genotypic differences in degree of resistance to E. veneta. In 8 of the families, the segregation of the H gene (presence of cane hairs) was studied and compared with disease incidence, measured on a 0 to 5 scale. H and h phenotypes gave average scores of 3.05 and 2.42, respectively, but other independent genes appeared to have more influence on resistance. These genes were dominant. In a study of 5 of the families, resistance to P. rubi-idaei was highly correlated with resistance to E. veneta. The mean counts of P. rubi-idaei telia per unit leaf area for H and h segregates were 17.1 and 4.1, respectively.