Application of biocontrol agents to regulate grey mould and powdery mildew on strawberries

Regulation of important diseases by means of pesticides is highly limited in the ecological production of strawberries. Thus, the application of biocontrol agents (BCAs) can serve as an alternative to chemical fungicides to regulate diseases on organically grown strawberries. But, usually growers do not consider the use of biocontrol agents as a reliable means for the control of strawberry diseases under field conditions. Fluctuating environmental conditions may be the causes for the unreliable effectiveness of BCAs. In addition, antagonistic interactions between different BCAs may also contribute to their reduced efficacy.
Since 2009 the German Federal Agency for Agriculture and Food is funding a project to develop application strategies for an optimised regulation of diseases by biocontrol agents in the ecological production of strawberries. In the subproject conducted at the Geisenheim Research Center the main focus is on the diseases grey mould (Botrytis cinerea) and powdery mildew (Podosphaera aphanis). The efficiency of various micro-organisms against B. cinerea and P. aphanis is tested in vitro and on detached flowers and leaves. The compatibility of selected BCAs is examined in vitro. Further tests on detached flowers and leaves with BCA combinations towards grey mould and powdery mildew are performed. Greenhouse trials are conducted to show the efficacy of the selected BCAs and BCA combinations against grey mould and powdery mildew on the plant. Furthermore, several BCAs and combinations of BCAs are tested in a field experiment against these diseases. In this experiment also effects on postharvest quality and side effects on other pathogens and pests will be recorded. Additionally, effects of BCA applications on the natural microflora of the plant`s phyllosphere and fruits as well as the fate of applied BCAs will be analysed by microbiological and biomolecular techniques. Finally, optimised application strategies will be introduced to ecologically cropping strawberry farmers. The results of this project might contribute to a more effective control of pathogens and help to encourage the hesitant farmers to switch from conventional to ecological cropping of strawberries.


Dr. Erika Krüger

Tel. +49 6722 502 563
Fax +49 6722 502 560