investigation on interaction of isolate-genotype between erysiphe betae and beta vulgaris under greenhouse condition

pathogenicity of 4 isolates of erysiphe betae from 4 different geographical zones of iran on 5 genotypes of beet, with different levels of resistance to powdery mildew, was investigated. eight-week old plants were inoculated by conidia from 4 isolates separately. indices for infection were estimation of leaf infection and number of produced conidia on the leaf surface 3 weeks after inoculation. results indicated that there was no significant difference on the virulence level of 4 isolates but the genotypes showed significant difference in susceptibility to fungal isolates. the genotype 7233 indicated the highest susceptibility and two genotypes 10417 and 14442 showed highly resistance to powdery mildew. the genotype “leaf beet” which in the field experiments in germany had proved resistance to the disease, in our greenhouse studies showed susceptible response. conclusive results indicated that different isolates of e. betae belonging to different geographical zones were similar in pathogenicity and also greenhouse experiments can be an appropriate manner for screening sugar beet genotypes against e. betae.