VIEW ARTICLE

Resistance

Host Specialization of Heterobasidion annosum. J. J. Worrall, Research assistant, Department of Plant Pathology, University of California, Berkeley 94720; J. R. Parmeter, Jr.(2), and F. W. Cobb, Jr.(3). (2)(3)Professor, and professor, respectively, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 73:304-307. Accepted for publication 31 August 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-304.

A total of 30 isolates of Heterobasidion annosum (Fomes annosus) from Pinus ponderosa and Abies concolor were inoculated into seedlings of both hosts in two greenhouse experiments. Two-way analyses of variance showed significant differential interaction between isolate groups and host species. Isolates from one host were more virulent on that host than isolates from the other host. Mortality data and tissue colonization patterns parallel observations of H. annosum on the two hosts in nature.