APS Abstracts of Presentations

First report of Perithecia of Phaeoacremonium viticola on grapevine (Vitis vinifera) and ash (Fraxinus latifolia) in California
Presenter: A. Eskalen, Dept. of Plant Pathology, University of California, Davis, CA
Co-Author(s): S. Rooney-Latham, Dept. of Plant Pathology, University of California, Davis, CA; W. Gubler, Dept. of Plant Pathology, University of California, Davis, CA
Phytopathology 95:S28

Esca and Petri diseases on grapevine are caused by Phaeomoniella chlamydospora and species of Phaeoacremonium including P. aleophilum, P. viticola, P. angustius, P. parasiticum, P. inflatipes, P. rubrigenum, and P. mortoniae. The teleomorph of P. aleophilum and P. mortoniae have been recently confirmed in California as Togninia minima (Tul. & C. Tul.) Berl. and T. fraxinopennsylvanica (Hinds) Hausner, Eyjólfsdóttir & J. Reid respectively. Teleomorphs of other Phaeoacremonium species have not been identified. However, perithecia resembling those of T. minima and T. fraxinopennsylvanica were found on the surfaces of old pruning wounds and in the cracks of cordons and trunks on Vitis vinifera cultivars Thompson Seedless, Riesling, and Cabernet Sauvignon. Perithecia were observed on grapevines in vineyards in six out of nine counties surveyed, viz. Yolo, Mendocino, El Dorado, Tulare, Madera, and Sonoma. Perithecia were also observed in dead vascular tissue of declining ash tree branches (Fraxinus latifolia) located in the vicinity of vineyards in Sonoma and Yolo counties. When plated onto PDA-tet medium, ascospores formed colonies of Phaeoacremonium viticola after 10 days of incubation at room temperature. Molecular data confirmed that these perithecia were the teleomorph of P. viticola, a previously unknown teleomorph it is currently being identified.

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