Occurrence of Gloeotinia temulenta on Tall Fescue in Oregon. S. C. Alderman, USDA-ARS National Forage Seed Production Research Center, Corvallis, OR, 97331. Plant Dis. 80:105. Accepted for publication 21 November 1994. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0105D.
Seed with 75 to 80% germination from a 1994 harvest of a field of tall fescue (Festuca arundinaceae Schreb), cv. Fawn, and a field of cv. Martin, located near Shedd, OR, were examined for presence of Gloeotinia temulenta (Prill. & Delacr.) M. Wilson, M. Noble, & E. Gray. Gloeotinia temulenta is a seed pathogen that reduces seed germination and causes blind seed in grasses. Gloeotinia temulenta infection was found in 10 to 20% of the seed. Percent infection was based on four samples of 96 seed, placed individually in 96-well plates and covered with 0.2 ml of water. After incubation at 220C for 1 h, a pink deposit of conidia at the bottom of some wells was indicative of seed infection. Conidia of G. temulenta were confirmed by microscopic examination. Seed from the 1995 harvest were collected from the fields sampled in 1994 and from three additional fields of Fawn located nearby. Infected seed per field ranged from 16 to 27% in 1995. This is the first occurrence of high levels of infection of G. temulenta in Oregon since 1958. Factors that may have contributed to the resurgence of blind seed include a state mandated reduction in open field burning (a practice used by growers to control blind seed and rid fields of straw residue) fields remaining in production more than 5 years late harvest, which results in heavier seed but increases seed shatter, leaving more infected seed in the field partial in-field cleaning during combining, which leaves lightweight seed in the field as an inoculum source and early maturity of cvs. Fawn and Martin, which flower in late spring when prolonged rainy periods can occur, providing conditions favorable for ascospore production and disease development. All of these factors occurred in the 1994 to 1995 crop years.