Fruit tree canker, caused by the fungus Neonectria ditissima, has become a threat for Swedish apple production. No efficient protective measures are available and no complete genetic resistance is known in apple. However, apple genotypes differ in the level of partial resistance which must be fully exploited. We aim to use recent advances in phenotyping for canker resistance to reveal genetic differences among rootstocks and clarify the impact of a rootstock on scion’s ability to resist the infection. Furthermore, we aim to enhance cultivars’ and rootstocks' genetic resistance with cultivation practices such as Ca fertilization. By that we will produce important knowledge and develop efficient tools for reducing canker damages in apple orchards, in Sweden and internationally. This knowledge will also be applicable for other tree species. The project will be performed by an international research team in collaboration with Äppelriket Österlen Ek. För.