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Title: FIRST REPORT OF DISCULA FRAXINEA ON CHINESE FRINGE TREE IN THE UNITED STATES AND ON WHITE ASH IN DELAWARE

Author
item GREGORY, N - UNIV OF DELAWARE
item MULROONEY, R - UNIV OF DELAWARE
item Rossman, Amy
item Castlebury, Lisa

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2004
Publication Date: 1/1/2004
Citation: Gregory, N.F., Mulrooney, R.P., Rossman, A.Y., Castlebury, L.A. First report of discula fraxinea on chinese fringe tree in the united states and on white ash in delaware. Plant Disease.Vol. 88(4),P.427,2004.

Interpretive Summary: An unknown disease on Chinese fringetree (Chionanthus retusis L.) appeared as irregular water-soaked lesions on leaves of the current year's growth. With time these lesions enlarged, turned darker brown, and coalesced, with necrotic areas turning dry and pale. Symptoms were also observed on white ash (Fraxinus americana L.), from which a similar fungus was isolated. Isolates from both Chinese fringe tree and white ash were identified as Discula fraxinea (Peck)Redlin & Stack, the anamorph of Gnomoniella fraxinii Redlin & Stack (Gnomoniaceae, Diaporthales). Molecular data including DNA analysis of large subunit and ITS sequences indicated that the isolates from both Chionanthus and ash were conspecific with Discula fraxinea from Maryland and Oregon. Isolates of D. fraxinea from Chionanthus retusis, green ash and white ash were inoculated and recovered on two and three year old trees of C. retusis and F. americana. This is the first report of Discula fraxinea on Chionanthus retusis. In addition, this is the first report of D. fraxinea on F. americana in Delaware. Chionanthus and Fraxinus are both members of the family Oleaceae. Plant pathologists and extension agents will use this research to determine the causal agent of anthracnose disease of Chinese fringe tree and white ash.

Technical Abstract: Leaf blight or anthracnose on Chinese fringe tree (Chionanthus retusis L.) appeared as irregular water-soaked lesions on leaves of the current year's growth. With time the lesions enlarged, turned darker brown, and coalesced, with necrotic areas turning dry and pale. Similar symptoms were observed on white ash (Fraxinus americana L.), from which a similar fungus was isolated. Isolates from both Chinese fringe tree and white ash were identified as Discula fraxinea (Peck)Redlin & Stack, an anamorph of Gnomoniella fraxinii Redlin & Stack (Gnomoniaceae, Diaporthales). Molecular data including DNA analysis of large subunit and ITS sequences indicated that the isolates from both Chionanthus and ash were conspecific with Discula fraxinea from Maryland and Oregon. Isolates of D. fraxinea from Chionanthus retusis, green ash and white ash were inoculated and recovered from two and three year old trees of C. retusis and F. americana. This is the first report of Discula fraxinea on Chionanthus retusis. In addition, this is the first report of D. fraxinea on F. americana in Delaware. Chionanthus and Fraxinus are both members of the family Oleaceae.