Author
 |
Alderman, Stephen |
|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/10/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Blind seed disease, caused by the fungus, Gloeotinia temulenta, is a potentially serious disease of forage and turf grasses grown for seed. The pathogen infects flowers or seed of grasses, resulting in low seed germination. High levels of blind seed disease were found in fields of tall fescue, grown for seed, in Oregon from seed harvested in 1994 and 1995. This is the first occurrence since 1958 of high levels of blind seed disease in Oregon. The extent of the disease and factors contributing to its reappearance are under investigation. Technical Abstract: Seed from a 1994 harvest with 75-80% germination from a field of tall fescue (Festuca arundinaceae Schreb.), cv Fawn, and a field of tall fescue, cv Martin, near Shedd, OR, were examined for presence of Gloeotinia temulenta (Prill. & Delacr.) M. Wilson, M. Noble & E. Gray, a seed pathogen that reduces seed germination and causes blind seed in grasses. G. Temulenta infection was found in 10-20% 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 water. After incubation at 22 C for one hour, a pink deposit of conidia at the bottom of some wells was indicative of seed infection. Conidia of G. temulenta were confirmed under 375x magnification. Seed from the 1995 harvest were collected from the fields sampled in 1994 and from three additional fields of Fawn tall fescue near the fields sampled in 1994. Infected seed per field ranged from 16-27%. This is the first occurrence in Oregon since 1958 of high levels of infection of G. temulenta. Factors which may have contributed to the resurgence of blind seed include a state mandated reduction in open field burning, a practice formally used by growers to control blind seed and rid fields of 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 leave infected lightweight seed in the field as an inoculum source; and early maturity of cultivars Fawn or 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 during the 1994-1995 crop year. |
