Abstract
Two new physiologic races of P. megasperma f. sp. glycinea were identified after hypocotyl inoculation of the differential soybean (Glycine max) vs. Harosoy, Harosoy 63, Sanga, Mack, Altona, PI [plant introduction] 171442 and PI 103091. The new races are proposed as races 21 and 22. The effect of the new races of cultivars now being developed with more than 1 major gene resistant to Phytophthora root rot is discussed.