Disease Note.

Penicillium Leaf Blight Caused by P. oxalicum on Creeping Bentgrass in North Carolina. K. J. Jones, Research Associate, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. . Plant Dis. 76:753. Accepted for publication 2 March 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0753B.

Leaf chlorosis followed by necrotic collapse of leaf bases and tips was observed on plants of Agrostis palustris Hudson (creeping bentgrass) grown under controlled environmental conditions and in pots in the greenhouse. A dense, dark gray sporulation was commonly observed on necrotic tissue. The causal agent was isolated and identified as Penicillium oxalicum Currie & Thorn. Inoculation was by brief inversion of a petri plate with actively sporulating colonies of P. oxalicum into humidity chambers containing 2-wk-old seedlings of A. palustris. Leaf blade chlorosis and necrosis were observed on inoculated plants after 2 wk. A. palustris plants grown in noninfested chambers showed no symptoms. P. oxalicum sporulated profusely on soil organic matter prior to host symptom expression and was reisolated from symptomatic A. palustris tissue. This is the first report of P. oxalicum causing a disease on A. palustris. The significance of P. oxalicum in the summer decline of creeping bentgrass in warm climates should be evaluated.