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Togninia minima is an important pathogen causing esca and grapevine declines worldwide. Although perithecia of T. minima have been produced in the laboratory, their presence in diseased vineyards has not been shown. In our study, perithecia of T. minima were found on grapevines in the field in five California counties. Perithecia were clustered on dead vascular tissue in deep cracks along trunks and cordons or on the surfaces of decayed pruning wounds. Field-collected perithecia were characteristic of T. minima perithecia previously produced in vitro and molecular sequence analysis of the internal transcribed spacer region of the nuclear ribosomal DNA additionally confirmed their identity. Ascospores from perithecia germinated on agar medium and formed colonies typical of T. minima. This is the first report of Z minima perithecia in diseased vineyards and suggests ascospores as an additional source of inoculum for new grapevine infections. [ABSTRACT FROM AUTHOR]

Reports on the occurrence of Togninia fraxinopennsylvanica on California's Esca-diseased grapevines and declining ash trees. Research findings; Research applications; Implications on studies of plant diseases.

From December 2004 through May 2009, samples were collected from California nurseries and wild lands to survey for Phytophthora ramorum and comply with federal regulations of nursery stock. Samples were prescreened by an enzyme-linked immunosorbent assay (ELISA) that detects Phytophthora spp. and tested by culture, P. ramorum-specific real-time polymerase chain reaction (PCR), and nested PCR. Yearly percentages of infected samples ranged from 0.6 to 2.3%. Camellia spp., Rhododendron spp., Magnolia spp., Pieris spp., and Laurus nobilis tested positive the most frequently in the nurseries and Lithocarpus densiflorus, Umbellularia californica, and Quercus agrifolia tested positive most often from wild lands. Of the 118,410 samples isolated onto PARP media, 0.8% was identified as P. ramorum. Of 115,056 samples tested by ELISA, 5.9% tested positive for Phytophthora spp. Of the 6,520 samples tested by PCR, 12.4% tested positive for P. ramorum. The false-negative, positive, and internal control failure rates of the assays are discussed. After removing the seasonal effect of sampling strategy, isolation of the pathogen into culture was found to be seasonally dependent whereas detectability by PCR and ELISA was not. To our knowledge, this is the first evaluation of a regulatory testing program for a plant pathogen on this scale using standardized assays. [ABSTRACT FROM AUTHOR]