Does apple canker develop independently on leaf scars of a single apple shoot?

European apple canker, caused by Neonectria ditissima, causes serious damage to trees, particularly young trees. Canker management is difficult because of the limited availability effective fungicides, long latency period, inoculum abundance and host resistance in commercial cultivars as well need for costly manual pruning interventions. To understand disease aggregation more management, we assessed whether canker infection subsequent lesion development on leaf scars are independent from each other same shoot. Four inoculation experiments were conducted: one glasshouse, three orchards. On shoot, 10 consecutive inoculated visible cankers over time situ. Number developed per shoot spatial distribution these within a was statistically analysed. Most data number lesions single failed fit binomial distributions (indicator independence) fitted much better beta distributions. In cases (4–20%), there appeared be positive association between neighbouring scars. However, experiment where laboratory incubation isolation N. ditissima but asymptomatic (after eight months’ field incubation) used results suggested independence We conclude that apparent individual shoots likely originate responses. Such should taken into consideration assessment management.