ASH ANTHRACNOSE CAUSED BY DISCULA FRAXINEA REPORTED FROM OREGON

Authors: Rossman, Amy; Castlebury, Lisa; PUTNAM, MELODIE - OREGON STATE U, CORVALLIS

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2003
Publication Date: 4/1/2004
Citation: Rossman, A.Y., Castlebury, L.A., Putnam, M. Ash anthracnose caused by discula fraxinea reported from oregon. Plant Disease. Vol. 88(2)p.222,2004.

Interpretive Summary: Fungi cause billions of dollars damage to crops and trees in the United States every year, yet many fungi that causes diseases on plants are relatively unknown. Fungi new to specific plants and their geographic distribution are still being reported. Ash anthracnose is a disease of ash trees that is well known throughout the United States but has never been reported from Oregon. In this research, the fungus that causes ash anthracnose was isolated from diseased leaves and accurately identified. Its occurrence in Oregon is reported for the first time. Plant pathologists will use this research to identify the fungus causing ash anthracnose as well as to determine the distribution of ash anthracnose in the United States.

Technical Abstract: Anthracnose on ash trees has been observed in Oregon for a number of years, yet no formal report of the existence of the disease or its causal fungus can be located in the literature. A fungus was isolated from acervuli developing on the undersurface of lesions on diseased leaves of ash (Fraxinus americana L.) in Oregon. Using both morphological, cultural and morphological characteristics, the fungus was identified as Discula fraxinea (Peck) Redlin & Stack (teleomorph: Gnomoniella fraxinii Redlin & Stack). On the host the fungus produced acervuli with hyaline, non-septate, ellipsoid conidia 5-11 x 2.5-6 um. The sequences of the ITS and LSU region of the nrDNA agreed with those of D. fraxinea. Ash anthracnose has been reported from the central and eastern United States and California as well as the prairie provinces in Canada and recently from British Columbia usually under the synonymous names Gloeosporidium aridum and G. fraxineum. The specimen of ash anthracnose from Oregon was deposited in the U.S. National Fungus Collections (BPI 843391), the derived culture was deposited as CBS XXXXX), and the sequences were deposited in GenBank as ITS = AFXXXX and LSU = ARXXXXX.