Improved Method for Isolating Phytophthora lateralis from Soil. P. B. Hamm, Research Assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. E. M. Hansen, Associate Professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Plant Dis. 68:517-519. Accepted for publication 4 January 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-517.

Recovery of Phytophthora lateralis from soil was improved by adding hymexazol to the baiting solution, then placing baits into a solid antibiotic medium. Port-Orford-cedar branchlet baits were floated over a soil sample in water amended with 25 μg/ml hymexazol. Baits were transferred after 6 days to cornmeal agar containing 20 μg/ml of pimaricin and 200 μg/ml each of vancomycin and streptomycin (CMP). Hymexazol in the baiting solution limited colonization by Pythium isolates. No effect on growth or sporulation of P. lateralis was observed. Hymexazol and the antibacterial amendments prevented faster-growing contaminants from masking or inhibiting growth of P. lateralis on CMP. P. lateralis was successfully recovered from naturally infested soil diluted 16 times with uninfested soil.