Impact of two-spotted spider mite Tetranychus urticae in soilless raspberry crops

Abstract: The two-spotted spider mite Tetranychus urticae Koch (TSSM) is a major pest onsoilless floricane-fruiting raspberries grown in plastic tunnels. The very favourable climaticconditions in tunnels can lead to big TSSM outbreaks. To minimize residues, pesticides areapplied before flowering and are based on an empirical threshold of 10% of terminal leafletsoccupied by at least one mobile TSSM form. However, this value is judged to be too high bymany growers. We studied the impact of various TSSM densities on the yield and fruit quality ofpotted raspberries (cv. Tulameen) in a plastic tunnel. TSSM reduced significantly yield and fruitquality. Thus, our first results stress the importance of a good mite control to ensure an optimalpayoff.