Susceptibility of pruning wounds to grapevine trunk disease pathogens Eutypa lata and Diplodia seriata in three climatic conditions in Australia

The grapevine trunk diseases Eutypa and Botryosphaeria dieback, caused by fungal species that infect pruning wounds, are a threat to vineyard longevity worldwide. This study evaluated the susceptibility of grapevine pruning wounds in three climatic regions of Australia. In field trials, wounds were made early, mid- and late winter, and inoculated with spores of Eutypa lata or Diplodia seriata at various times, from 1 to 112 days after pruning. For both pathogens, wounds were highly susceptible immediately after pruning, followed by a rapid decrease in susceptibility over the next 14 days in McLaren Vale and Adelaide Hills, South Australia, whereas the period of susceptibility was longer in Big Rivers, New South Wales, where high natural disease pressure of D. seriata confounded results. In the Adelaide Hills, delaying pruning to late winter may reduce the risk of infection by E. lata. A detached cane assay confirmed that the duration of susceptibility of six commonly grown cultivars to E. lata infection was similar.