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 (‘Braeburn’, ‘Scilate’, ‘Fuji’, ‘Golden Delicious’, ‘Jonathan’ and ‘Royal Gala’) grafted onto two rootstocks (‘M793’ and ‘M9’) 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 ‘M793’ showed a significant wood age effect on disease incidence and lesion length, which was similar to cultivars grafted on ‘M9’. 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 ‘Royal Gala’ 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.