APS Abstracts of Presentations

Spore release of Phaeomoniella chlamydospora associated with grapevine cordons in California. A. ESKALEN, S. R. Latham, and W. D. Gubler. University of California, Davis, CA. Phytopathology 94:S28. Publication no. P-2004-0184-AMA.

The fungus Phaeomoniella chlamydospora causes Petri disease (syn. Young vine decline) and is also associated with esca (Black measles) of grapevines in California and many other grape production countries. Spore traps were placed in selected vineyards where Petri disease was known to occur. Spore trapping data were collected weekly throughout 2002 and 2003. Results showed that spores of Pa. Chlamydospora were trapped in Napa, Sonoma, Mendocino, Tulare, San Joaquin, San Luis Obispo, Madera and Solano Counties. Successful trapping of Pa. Chlamydospora in each case was correlated with rainfall events in each location. Pycnidia of Pa. Chlamydospora were found under exfoliating bark of grapevine cordons and on 2-3 year-old pruning wounds on cordon spurs. Spores from pycnidia were shown to be viable and pathogenic. These results showed conclusively that Pa. Chlamydospora has the ability to act as airborne inoculum in California vineyards during winter and spring rainfall. Pruning wounds were shown to be susceptible for up to 4 months.

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