Evaluation of fungicides for the management of Botryosphaeria dieback diseases of grapevines

BACKGROUND: A range of botryosphaeriaceous species can cause dieback and cankers in grapevines; however, different species most commonly affect the grapevines in different grape-growing regions and countries. They infect through wounds and sporulate on woody stems and green shoots throughout the year, so wound protection is the recommended control strategy. This research evaluated fungicides for their ability to reduce mycelial growth and conidial germination of three botryosphaeriaceous species and to protect pruning wounds against infection. RESULTS: In vitro experiments showed that nine out of 16 tested fungicides were effective at reducing mycelial growth and/or conidial germination of three isolates each of Neofusicoccum australe, N. luteum and Diplodia mutila. The species differed in their response to the fungicides, although N. luteum was usually the least sensitive. When nine selected fungicides were sprayed on cane pruning wounds on potted and field grapevines and subsequently inoculated with N. luteum conidia, some effectively protected them from infection. The most effective fungicides were flusilazole, carbendazim, tebuconazole, thiophanate-methyl and mancozeb, as they prevented the inoculated pathogen from infecting healthy wood in 100, 93, 87, 83 and 80% of field vines, respectively. CONCLUSION: This research has demonstrated that fungicides applied after winter pruning can protect vines from infection by conidia of three botryosphaeriaceous species. (C) 2012 Society of Chemical Industry