First Report of Magnaporthe poae, Cause of Summer Patch on Annual Bluegrass, in Ohio. J. C. Stier, Department of Plant Pathology, The Ohio State University, Columbus 43210. W. W. Shane, Department of Plant Pathology, The Ohio State University, Columbus 43210. Plant Dis. 74:252. Accepted for publication 4 December 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0252B.
Magnaporthe poae Landschoot & Jackson (2), the cause of summer
pa1ch (1), was isolated from symptomatic annual bluegrass (Poa annua
L.) in golf course putting green at Cincinnati and Columbus during
the summer of 1988. Small (<15 cm chlorotic patches typical of the
early symptoms of summer patch consisted of plants with decayed
crowns and discolored roots covered with dark ectotrophic hyphae.
The teleomorph, required for accurate identification, was produced
in vitro (acidified potato-dextrose agar) only wben paired with the
compatible mating type (2). Perithecia, asci with refractive apical rings,
and ascospore morphology and measurements were similar to those
reported by Landschoot and Jackson (2). Pathogenicity of Ohio
isolates was verified with Koch's postulates in greenhouse studies.
Kentucky bluegrass (P. pratensis L. 'S-21') and P. annua were
inoculated with millet seed infested with M. poae at the time of planting
in sterilized sand. This is the first published report of M. poae in