PLANT PROTECTION CHALLENGES IN STRAWBERRY PRODUCTION IN NORTHERN EUROPE

Strawberry is cultivated in north Europe, also in the higher latitudes and it is the most important soft fruit crop in Finland. The cool climate has limited the spread of many strawberry pests to Finland, but this is now changing. Benefiting from the warming climate, strawberry tarsonemid mite (Tarsonemus pallidus) continues to be the most important pest. Biological control by use of predatory mites is widely adopted by growers. Two-spotted spider mite (Tetranychus urticae) is favoured by use of fibre cloth used to protect plants during winter and spring. Strawberry blossom weevil (Anthonomus rubi) and European tarnished plant bug (Lygus rugulipennis) are among the key pests, and in northern Finland strawberry leaf beetles (Galerucella spp.) can cause severe damage. Monitoring methods have been developed for these pests. Warming climate has increased thrips damage on fruits, and favours also the black vine weevil (Otiorhynchus sulcatus). Grey mould (Botrytis cinerea) is the main disease, and controlled with fungicides. Recently, also biological control has become more popular. Crown rot (Phytophthora cactorum) has spread to production fields. However, anthracnose (Colletotrichum acutatum) has not established itself in production fields. Leaf diseases (Mycosphaerella fragariae, Diplocarpon earlianum and Gnomonia comari) are quite common and powdery mildew (Podosphaera aphanis) has not been an important disease in open field. The main vector of strawberry viruses, strawberry aphid (Chaetosiphon fragaefolii), occurs not yet in Finland. In the future, mites are expected to be more harmful and also thrips and black vine weevil are favoured by warmer conditions. Considering diseases, Phytophthora species can be expected to increase in Finnish strawberry fields.