Abstract Canes obtained from one-year-old stems of the grapevine cultivars Cabernet Franc, Malbec, Merlot, Sauvignon Blanc and Syrah (all non-grafted) were used as models to test their susceptibility to Diplodia seriata and Diplodia mutila. The results showed that the mean length of lesions caused by D. mutila was 3.2 times larger than that produced by D. seriata. In addition, the Cabernet Franc and Syrah cultivars were the most susceptible to D. mutila, while Merlot and Malbec were the least susceptible. No significant differences were observed between cultivars inoculated with D. seriata. The results are discussed in terms of the susceptibility of the different grapevine cultivars to both pathogens.