The effect of wood age on infection by <i>Neonectria ditissima</i> through artificial wounds on different apple cultivars
The age of apple wood may affect its susceptibility to European canker (Neonectria ditissima). Therefore, a glasshouse experiment was conducted with potted trees of six apple cultivars (â€˜Braeburnâ€™, â€˜Scilateâ€™, â€˜Fujiâ€™, â€˜Golden Deliciousâ€™, â€˜Jonathanâ€™ and â€˜Royal Galaâ€™) grafted onto two rootstocks (â€˜M793â€™ and â€˜M9â€™) to study the effect of 3-, 2- or 1-year-old wood on incidence and disease progression following inoculation with conidia of N. ditissima. Initial analyses of cultivars on â€˜M793â€™ showed a significant wood age effect on disease incidence and lesion length, which was similar to cultivars grafted on â€˜M9â€™. Three-year-old wood developed more and longer lesions than either the 2- or the 1-year-old wood. A significant cultivar effect was observed with â€˜Royal Galaâ€™ developing more lesions than the other cultivars tested. More than half of asymptomatic wounds placed onto apple sap-amended water agar for pathogen isolation yielded N. ditissima.