Phytophthora Root Rot of Cabbage and Cauliflower in Oregon. P. B. Hamm, Research Assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. P. A. Koepsell, Extension Plant Pathologist, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Plant Dis. 68:533-535. Accepted for publication 5 March 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-533.

Root rot of cabbage (Brassica oleracea var. capitata) and cauliflower (B. oleracea var. botrytis) caused by Phytophthora megasperma is reported for the first time in Oregon. Naturally infected cabbage plants were confined to low areas in fields where water accumulated. Root rot of cauliflower was especially destructive in low-lying areas but also extended to higher ground. Cabbage was more tolerant than cauliflower to infection by P. megasperma in pathogenicity tests. Differences in susceptibility to Phytophthora root rot among cultivars of cabbage and cauliflower are reported.