Screening perennial Helianthus species for powdery mildew

Abstract

Powdery mildew (Erysiphe cichoracearum) has been reported as a potential constraint for sunflower growing in regions with warm climate. Severity of disease varies depending on the sunflower genotype. Aim of this research was to determine response of wild Helianthus species grown in IFVC wild species collection to powdery mildew, as there are not many references on the reaction of wild sunflowers to this disease. Disease severity was recorded in naturally infected field during four year period. Total of 23 Helianthus spp. (333 accessions) were included in the survey. Reaction to powdery mildew varied among years and species with the highest occurrence of disease in 2011. There was significant difference in disease occurrence among accessions of the same species. During 4-year survey period, powdery mildew was not recorded in 6, 10 and 6 accessions of H. decapetalus, H.divaricatus, and H. laevigatus, respectively. Moreover, complete absence of disease was registered in another 10 species represented by one or two accessions. Accessions of other surveyed species differed in susceptibility and percentage of susceptible ones varied between 50% for H. giganteus and 89% for H. tuberosus.