Demonstration project “Exclusion netting for managing spotted wing drosophila in fruit crops”: results 2017

The invasive pest, Spotted Wing Drosophila Drosophila suzukii Matsumura (SWD), has become a substantial threat to European fruit cultivation. A technical possibility of control is the use of exclusion netting. In 2017, the BMEL-funded demonstration project has started, including 19 producers of cherry, raspberry, blackberry and blueberry. The cherry orchards were covered with foil canopies and netted laterally. Berry cultures were equipped with foil tunnels in combination with nets or nets only. The nets had different mesh sizes varying between 0.8 × 0.8 mm and 1.3 × 1.3 mm. Due to frost damages and late infestation pressure in 2017, the examination was limited. Yet, the positive effect of exclusion netting was evident. Despite of captures of Spotted Wing Drosophila outside of the netted crops no or only limited fruit infestation occurred within the exclusion nettings. In most cases higher temperatures and lower relative humidity was measured within exclusion netting, but to different extents in the course of the day. The first year showed that the differences in microclimate were mainly caused by the foil system and not by the net: larger differences were found in berry cultures protected with netted foil tunnels than in laterally netted foil canopies of cherries. Nevertheless, the differences in microclimate were negligible. The exclusion nets also reduced other pests like cherry fruit fly or summer fruit tortrix. Consideration must be borne in mind that if a pest can enter the exclusion netting system it can establish rapidly and hence, plant protection products may still be required. Furthermore, problems with the assembly of the nets and deficiency in pollination in some netted raspberry tunnels became apparent .