OCCURRENCE AND DISTRIBUTION OF ERGOT AND ESTIMATES OF SEED LOSS IN KENTUCKY BLUEGRASS GROWN FOR SEED IN CENTRAL OREGON

In 1991 to 1993, ergot was detected in 36, 44, and 62%, respectively, of fields of Kentucky bluegrass grown for seed in central Oregon. Rela tively few fields (2 to 13%) had a high (more than 20 sclerotia/gm see d) level of ergot. Ergot severity (percent sclerotia by weight) in 199 1 to 1993 was estimated at 0.85, 0.07, and 0.34%, respectively. Percen t seed replaced by ergot in 1991 to 1993 was estimated at 0.22, 0.02, and 0.08, respectively. Recleaning of seed to reduce ergot contaminati on and to meet purity standards resulted in a 7.8% reduction in market able seed weight. Estimated value of seed replaced by ergot in 1991, 1 992, and 1993, was $75,625, $4,758, and $17,076, respectively. Estimat ed value of seed lost during recleaning in 1991, 1992, and 1993, was $ 37,669, $8,171, and $21,964, respectively. Weed grasses supporting erg ot at the time of harvest of Kentucky bluegrass were species of Bromus , Secale, Festuca, and Pea. However, very few seed heads of weed grass es were infected, and they appeared to contribute little to ergot deve lopment in central Oregon. Most infested fields (with more than one sc lerotium/gm seed prior to recleaning) or weed grass sites with ergot w ere located in the southern range of the area of study.