Grey mold caused by Botrytis cinerea is a serious strawberry disease. Yield loss is prevented by repeated fungicide treatments during flowering which increases the risk of pesticide residues in berries. Fruit lesions are typically initiated from B. cinerea infected stamens or from dead infected petals adhering to the fruit or trapped under the calyx. To implement biological control agents (BCAs) as an alternative control measure, it is crucial that the BCAs are able to colonize flower parts rapidly to combat B. cinerea. The combination of fungicides with BCAs may enhance and stabilise the efficacy of BCAs. The underlying mechanism for such positive combination effects may be related to an improved establishment of the BCAs when their natural competitors have been adversely affected by the fungicide or that the B. cinerea infection has been slowed down.
The present work report results on 1) the interaction between BCAs and B. cinerea on strawberry flowers, 2) the sensitivity of BCAs to strawberry fungicides, and 3) the effect of combined BCA+fungicide treatment on BCAs and on the indigenous mycobiota.