|Coats, Dale - OSU,RES CENTER, MADRAS,OR|
|Crowe, Fred - OSU, CORVALLIS, OR|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 20, 1996
Publication Date: N/A
Interpretive Summary: Ergot, caused by the fungus Claviceps purpuea, is an important disease of Kentucky bluegreass grown for seed in Oregon, Washington, and Idaho, although few studies have quantified the impact of the disease on seed production. The fungus replaces seed with a hard, black fungal body (ergot). Between 1991 and 1994, seed from Kentucky bluegrass fields in eastern Oregon contained ergot contamination as high as 47% by weight (25% direct seed loss). An additional 9% loss was estimated from recleaning seed to remove ergot. Ergot contamination was less than 1% in the 1991-93 seed crops, but in 1994, 1-2% by weight of the total cleaned seed crop was ergot. This study provides the first quantitative data on yield loss in Kentucky bluegrass from ergot.
Technical Abstract: The impact of ergot on production of Kentucky bluegrass grown for seed in eastern Oregon was determined. Ergot severity (percent sclerotia by weight) in Kentucky bluegrass seed in 1991-94 was 0.20, 0.04, 0.07, and 1.15%, respectively. Percent seed replaced by sclerotia in 1991-94 was 0.05, 0.01, 0.03, and 0.44%, respectively. High levels of ergot occurred in only two of fthe six cultivars examined. In susceptible cultivars as many as 504 sclerotia/g of seed were detected. This equated to 47% ergot by weight or 25% infected seed. A significant relationship between ergot severity and yield was not detected. However, a 9% reduction in marketable seed weight occurred when seed lots contaminated with ergot were recleaned to meet purity standards.