Tolerant and Root-Resistant Soybean Cultivars: Reactions to Phytophthora Rot in Inoculum-Layer Tests

Race specificity may be involved in the reactions of certain soybean [Glycine max (L.) Merr.] cultivars previously characterized as tolerant to Phytophthora megasperma f. sp. glycinea Kuan & Erwin (Pmg). The objectives of this study were to determine if an inoculum-layer procedure could be used to differentiate race-specific reactions among soybean cultivars characterized as tolerant to Pmg and to distinguish root resistance reactions associated with tolerance from those conditioned by the Rps 2 gene. An inoculum- layer procedure was used in the greenhouse to determine the reactions of 21 soybean cultivars to Races 1 and 10 of Pmg