Control of Botrytis cinerea in strawberries with Gliocladium catenulatum vectored by bumblebees

Abstract

BACKGROUND: Grey mould Botrytis cinerea is the most common fruit rot disease in strawberries and shelf-life is often limited because of Botrytis. Generally the disease is controlled by spraying chemical products. OBJECTIVE: To prevent resistance and to produce strawberries with fewer residues, it is required to find alternatives. In this study, bumblebees were used as vector to transport the antagonistic fungus Gliocladium catenulatum J1446 to the flowers in order to control Botrytis. METHODS: A trial was conducted in strawberries grown in a plastic greenhouse. Bumblebees leaving the special hive become loaded with the microbial product. The following strategies were compared: untreated control, conventional chemical spray scheme, spray application with G. catenulatum or fenhexamid, G. catenulatum (vectored). The last strategy is also tested with an additional spraying with G. catenulatum (1x) or fenhexamid (1x). Botrytis infection and yield were evaluated. RESULTS: Spray applications with G. catenulatum (3x) or Teldor (1x) did not reduce the Botrytis infection in this trial. G. catenulatum vectored by bumblebees reduced grey mould, and was comparable with the conventional chemical treatment scheme. Additional sprayings with G. catenulatum or fenhexamid did not generate an additional reduction. CONCLUSIONS: This greenhouse trial demonstrates that G. catenulatum vectored by bumblebees can reduce Botrytis infection and improve shelf-life of strawberries at low to moderate disease pressure. This results in a more sustainable control with healthier strawberries with fewer residues.