VIEW ARTICLE

Germination In Vitro of Pythium aphanidermatum Oospores. M. E. Stanghellini, Associate Professor, Department of Plant Pathology, University of Arizona, Tucson 85721; J. D. Russell, Laboratory Technician, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 63:133-137. Accepted for publication 1 August 1972. DOI: 10.1094/Phyto-63-133.

Oospores of Pythium aphanidermatum germinated in 1.5 hr, but maximum germination (20%) occurred after 12-hr incubation at 35 C on cornmeal agar. Germination was increased to 94% by oospore passage through live water snails. Cardinal temperatures for oospore germination, 15-35-45 C, coincided with those for linear growth. Germination occurred over a pH range of 5.2 to 8.6, with an optimum between 6.0 and 8.0. Oospore germination consisted of two distinct stages: (i) absorption of the endospore wall which was dependent upon an exogenous source of calcium; and (ii) production of a germ tube which was dependent upon an exogenous carbohydrate source.