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Previous surveys conducted in commercial nurseries found that different wood fungi, namely Cylindrocarpon spp., Botryosphaeriaceae, Phomopsis viticola and Phaeomoniella chlamydospora infect grapevine cuttings. Two field trials were carried out to evaluate the effectiveness of cyprodinil + fludioxonil, pyraclostrobin + metiram, fludioxonil and cyprodinil to prevent or reduce natural infections caused by such fungi. Rootstock and scion cuttings were soaked in fungicidal suspensions for 50 min prior to grafting. After callusing, the grafted cuttings were planted in two commercial field nurseries with and without a previous history of grapevine cultivation. After nine months in the nursery, the plants were uprooted and analysed for the incidence and severity of the wood fungi. Plants uprooted from the field without a previous history of grapevine cultivation were generally less strongly infected by wood fungi. Under this condition, only the mixture cyprodinil + fludioxonil simultaneously reduced the incidence of Cylindrocarpon and Botryosphaeriaceae fungi, as well as the severity of Cylindrocarpon infections. Treatments did not produce significant differences in the incidence and severity of P. viticola, and Pa. chlamydospora. For plants grown in the field with a grapevine history, all fungicides except cyprodinil significantly reduced the incidence and severity of Cylindrocarpon fungi. Also, the incidence and severity of Botryosphaeriaceae pathogens were significantly decreased both by cyprodinil + fludioxonil and by cyprodinil. No significant differences were noticed for P. viticola incidence and severity, and Pa. chlamydospora was not detected again. These results suggest that the practice of soaking grapevine cuttings in selected fungicides prior to grafting significantly reduces Cylindrocarpon spp. and Botryosphaeriaceae infections, thus improving the quality of planting material.

Black foot disease of grapevine is caused by Cylindrocarpon spp., with C. destructans being the main pathogen isolated from vine cuttings and young vineyards in Portugal. Few recommendations for black foot disease control are presently available, and they are not easy to implement within commercial nurseries. In this study, 14 fungicides were evaluated for their effect on the mycelial growth and conidium germination of four field isolates of C. destructans. Mycelial growth of the pathogen was inhibited by DMI fungicides, prochloraz (EC50 values

Due to its fungistatic or fungicidal potential, chitosan, a high molecular-weight polymer that is non-toxic and biodegradable, has become an alternative to conventional fungicides. In addition, chitosan is reported to elicit defense mechanisms in plant tissues. In this study, we explored the in vitro fungicidal effect of chitosan on some of the most important grapevine wood fungi, such as Botryosphaeria sp. (dieback and cane blight), Phomopsis sp. (Phomopsis cane and leaf spot), Eutypa lata (eutypa dieback), Neonectria liriodendri (black foot disease), Phaeomoniella chlamydospora (Petri disease and esca) and Fomitiporia sp. (esca). Inhibition of mycelial growth was evaluated at five concentrations 50, 25, 5, 2.5 and 0.5 mg a.i. l-1 of chitosan. Chitosan was effective in reducing mycelial growth of all the fungi. The lowest EC50 values were obtained with Pa. chlamydospora, Fomitiporia sp. and Botryosphaeria sp., and the highest with Neon. liriodendri. All these were inferior to the maximum recommended field rate (8.33 mg a.i. l-1) with exception of the value obtained with Neon. liriodendri. Greenhouse experiments were carried out to evaluate the efficacy of foliar sprays of chitosan on potted grapevine plants (cultivar Castelão) growing in a substrate artificially infested with Pa. chlamydospora or Neon. liriodendri. The effect of chitosan against Neon. liriodendri was similar to that achieved with some selected fungicides (carbendazim+flusilazole, cyprodinil+fludioxonil and tebuconazole). Chitosan significantly improved plant growth (plant height and number of roots) and decreased disease incidence compared with untreated plants. As regards Pa. chlamydospora, chitosan only reduced the disease incidence caused by this fungus.