Pathogenicity ofCeratobasidium cornigerumand Related Fungi Representing Five Anastomosis Groups

Abstract

Pathogenicity of 40 isolates of C. cornigerum and related binucleate Rhizoctonia solani-like fungi representing 5 Ceratobasidium anastomosis groups (CAG 1-5) was evaluated on 8 plant species [French bean (Phaseolus vulgaris), pea (Pisum sativum), radish (Raphanus sativus), onion (Allium cepa), wheat (Triticum aestivum), peanut (Arachis hypogaea), lettuce (Lactuca sativa) and tomato (Lycopersicon esculentum)] representing 6 families. Isolates in CAG 1 were pathogenic on gramineous hosts but nonpathogenic or only weakly virulent on species in other families. Isolates in CAG 2 were weakly virulent on pea and French bean seedlings and nonpathogenic on other species. Isolates from CAG 3, 4 and 5 exhibited a wide host range, were more virulent and caused seed, root and/or hypocotyl decay. Isolate .times. soil temperature interactions for disease development were observed in inoculations of wheat and pea seedlings.