Two New Physiologic Races of Phytophthora megasperma f. sp. glycinea. F. A. Laviolette, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. K. L. Athow, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. Plant Dis. 67:497-498. Accepted for publication 5 November 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-497.

Two new physiologic races of Phytophthora megasperma f. sp. glycinea have been identified after hypocotyl inoculation of the differential soybean (Glycine max) cultivars Harosoy, Harosoy 63, Sanga, Mack, Altona, PI 171442, and PI 103091. The new races are proposed as races 21 and 22. The effect of the new races on cultivars now being developed with more than one major gene resistant to Phytophthora root rot is discussed.