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

Abstract: Grey mould Botrytis cinerea is the most common fruit rot disease in strawberries and shelf-life is often limited because of Botrytis infections. To control this disease, bumblebees (Bombus terrestris) were used as vector to transport the antagonistic fungus Gliocladium catenulatum J1446 (Verdera B4) to the flowers using the Flying Doctors® system (Biobest). This system consists of a bumblebee hive with an integrated product dispenser. Bumblebees leaving the hive walk through the dispenser filled with Verdera B4 and become loaded with the microbial product. The following treatments were compared to test the impact of G. catenulatum vectored by bumblebees: untreated control, conventional chemical spray scheme, conventional spray application together with G. catenulatum. In addition, it was investigated whether the efficacy of Verdera B4 (vectored) could be improved by combined spraying with G. catenulatum (1x) or Teldor (1x). Botrytis infection pre- and post harvest, and yield were evaluated. This greenhouse trial demonstrated that G. catenulatum vectored by bumblebees reduced Botrytis infection and improved shelf-life of strawberries, comparable with a conventional chemical treatment scheme. This resulted in a more sustainable control with healthier strawberries with fewer residues.