Interspecific and Intraspecific Differentiation Within the Genus Cronartium by Isozyme and Protein Pattern Analysis. H. R. Powers, Jr., Chief Research Plant Pathologist, USDA Forest Service, Southeastern Forest Experiment Station, Athens, GA 30602. D. Lin, and M. Hubbes. Research Associate, and Professor of Forest Pathology, Faculty of Forestry, University of Toronto, Toronto, Ontario, Canada. Plant Dis. 73:691-694. Accepted for publication 5 March 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989. DOI: 10.1094/PD-73-0691.

Isozyme analyses were made on aeciospore collections from several species of the genus Cronartium and from several formae speciales of C. quercuum. Aeciospores from closely related Endocronartium harknessii also were tested. Esterase isozyme patterns provided the best differentiation. Patterns for Cronartium spp. differed markedly from those for E. harknessii. C. q. f. sp. banksianae, C. q. f. sp. virginianae, C. q. f. sp. echinatae, and C. q. f. sp. fusiforme were easily distinguished. The tests did not detect variation within formae speciales.