Survival of Pythium aphanidermatum in Golf Course Turfs. T. J. Hall, Graduate Research Associate, Department of Plant Pathology, The Ohio State University, Columbus 43210. P. O. Larsen, Associate Professor, and A. F. Schmitthenner, Professor, Department of Plant Pathology, The Ohio State University, Columbus 43210, and Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 64:1100-1103. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-1100.

Pythium aphanidermatum survival in turfs of bentgrass and annual bluegrass was primarily associated with thatch. Depending on the site and time of year, propagule densities in thatch were higher than in soil, on a weight basis and volume basis. P. aphanidermatum was isolated frequently from undecayed coarse material in thatch and live roots and occasionally from live shoots. Propagule numbers fluctuated seasonally in both sieved thatch and soil. Numbers were highest from November through January, declined during April and May, and then increased from mid-July until October. Oospores from thatch collected in January germinated and were identified as P. aphanidermatum, suggesting that oospores may be an overwintering form of the fungus. Bentgrass plants that were inoculated with thatch and soil fractions became diseased. This viable inoculum from naturally infested turfgrass occurred throughout the 15-mo sampling period.

Keyword(s): cottony blight, Pythium blight, turfgrass diseases.