Pathogenic diversity of Sclerotium rolfsii populations infecting sugar beet crops from Mediterranean-type climate regions

Abstract

The pathogenic diversity among and within 12 myceli al compatibility groups (MCGs) previously identified from a population of 459 Sclerotium rolfsii isolates infecting autumn-sown sugar beet crops in Mediterranean-type climate regions of Chile, Italy, Portugal, and Spain were determined to 11 economically important host crops. Across the tested plant species, MCG ii and iv were highly virulent, MCGs i, iii, ix and x moderately virulent and MCGs iv, v, vii, viii, xi and xii were low virulent. Similarly, across MCGs, chickpea and sunf lower were highly susceptible, pepper, watermelon, cotton and tomato susceptible, broccoli , sugar beet, and melon, moderately susceptible, and wheat and corn were resistant. There was no MCG -host species significant interaction. Establishing the variability in virulence among S. rolfsii isolates is of importance for management of Sclerotium root rot diseases in crops that can pote ntially be affected.