Infection biology as the basis of integrated control of apple canker (Neonectria ditissima) in Northern Europe

Abstract Background European canker, caused by Neonectria ditissima , is a disease of worldwide importance in apple production, yet knowledge about it limited, highly regional and sometimes contradictory. This an obstacle to successful management. Key aspects for Northern Europe are reviewed, based on research results from Germany Norway international literature data. Main topics Trunk cankers developing young trees within the first 1–3 seasons explanting can often be traced back latent infections initiated nurseries. The most important nursery infection lateral canker main trunk ‘knip’ trees, which standard tree type Europe. In strongly affected batches, up 25% have uprooted after growing season due such cankers. establishment maintenance healthy orchards requires clean material, especially case susceptible cultivars. Germany, commercial proceed through wounds fruit picking or leaf fall autumn, as shown appearance following spring high efficacy fungicide treatments at fall. Ascospores, commonly thought relevant long-distance spread infections, not released until end even wet autumn Germany. Therefore, their role remains unclear. Strong nitrogen-induced vegetative growth favours canker. field trials conducted under conditions current practices, autumnal sprays with copper hydroxide oxide were consistently more efficacious than oxychloride captan preventing new infections. Conclusions Restricted fertilisation other measures curb excessive during few years orchard, repeated pruning well-timed effective fungicides essential IPM Nonetheless, capable severely impairing success cultivars regions climates if all available taken. opens long-term perspectives breeding resistant