Cryptovalsa ampelina on Grapevines in N.E. Spain : Identification and Pathogenicity

Surveys conducted in diseased vineyards in Catalonia (N.E. Spain) showed that Cryptovalsa ampelina was very abundant on pruned canes, although it was isolated occasionally from necrotic wood of living plants. Identification of C. ampelina from the pruned canes was based on the morphology of the teleomorph. Its polysporous asci and pigmented allantoid ascospores distinguish it from Eutypa lata, the causal agent of eutypiose. However, cultures of C. ampelina are practically indistinguishable from cultures of other diatrypaceous species, therefore a PCR-based test was developed to identify cultures isolated from cankered wood. The designed species-specific primer pair (Camp- 1/Camp-2R) allowed for the unambiguous identification of C. ampelina in all tested cases involving cultures of diatrypaceous fungi. Additionally, the specificity of the primer pair to C. ampelina was confirmed by testing it on the host and on several other fungi known to occur on grapevine, namely species in the genera Botryosphaeria, Fomitiporia, Phaeoacremonium, Phaeomoniella and Phomopsis. The pathogenicity of C. ampelina on grapevine was confirmed through the observation of significant vascular lesions in artificial inoculations of grapevine plants, but the low frequencies of both mycelium reisolation and wound canker extension would suggest a low virulence for this fungus. Although C. ampelina does not appear to be a major pathogen of grapevine, its implication as a contributing factor to the decline of grapevines should deserve further investigations