Challenges for plant protection of berry crops in northern Europe

A cool climate has limited the berry species and cultivars grown, but also the spread and establishment of many berry pests. In Finland, the strawberry is the most important soft fruit crop, but currants and raspberry are also grown, mainly for fresh consumption. Increasing imports of plant material brings pests and diseases to new areas, and recently Phytophthora fragariae has been detected on strawberry, and P. rubi on raspberry, on Finnish berry farms. In northern areas, strawberry is grown as a perennial crop and soil-borne pathogens such as the Phytophthora species can be more damaging than in shorter rotations. The pests already present in production fields also benefit from warmer conditions. The strawberry tarsonemid mite (Phytonemus pallidus) is the most important pest on strawberry, and the two-spotted spider mite (Tetranychus urticae) is increasing in importance on all berry crops. The warming climate has increased thrips damage on strawberry fruits, and also favours the black vine weevil (Otiorhynchus sulcatus). On raspberry, increasing cultivation of a susceptible cultivar has increased the importance of raspberry leaf and bud mite (Phyllocoptes gracilis), the vector of Raspberry leaf blotch virus (RLBV). On strawberry, viruses and nematodes are potential emerging pests. In the warming climate, new berry species can be grown and bring new pest and disease problems, and changing production will challenge plant protection, in terms of both knowledge and techniques. Integrated pest management, mandatory in the European Union, benefits biological control.