APS Abstracts of Presentations

Epiphytic occurrence of esca and Petri disease pathogens on grapevine tissues. A. ESKALEN, S. R. Latham, A. J. Feliciano, and W. D. Gubler. Dept. of Plant Pathology, University of Califonia, Davis, CA 95616. Phytopathology 93:S24. Publication no. P-2003-0172-AMA.

Spores of Phaeoacremonium spp. and Phaeomoniella chlamydospora have been successfully trapped in California vineyards. These fungi have been shown to cause infection by water splashing onto susceptible pruning wounds. Various grapevine tissues, soil samples and standing water were collected from different vineyards to test for the epiphytic presence of these fungi. All samples were washed in sterile distilled water and filtered before culturing them onto plates of potato dextrose agar amended with tetracyline. Pa. chlamydospora was isolated most commonly from the surface of spurs, cordons, trunks and old lignified tendrils. Phaeoacremonium spp. were also commonly isolated from the surfaces of spurs, surfaces of roots, leaves, clusters and in soil. It is possible that many of the positive isolations were from tissues previously infected and diseased. However, since many of the tissues were asymptomatic or were not positive for these fungi when surface sterilized and cultured, it is speculated that these fungi may have the ability to survive epiphytically on grapevines.