Control of Botrytis cinerea in strawberries by biological control agents applied as single or combined treatments

Abstract

There is little knowledge about the effects of simultaneously applied biological control agents (BCAs) on the incidence of grey mould (Botrytis cinerea) in strawberries under field conditions. Our objective was, therefore, to investigate the use of three BCAs (Bacillus amyloliquefaciens FZB42, Aureobasidium pullulans DSM 14940 and DSM 14941 and Beauveria bassiana ATCC 74040) with respect to their efficacy against B. cinerea in field grown strawberries following single compared to combined application. In two subsequent years (2011 and 2012), improved control of B. cinerea resulted from combined BCA treatments, whereas the single BCAs were not efficient. Efficient combinations of BCA treatments were not the same in 2011 and 2012, however. The development of B. cinerea was reduced by single treatments of B. amyloliquefaciens and A. pullulans as well as by most combined BCA treatments during storage for one of two fruit samples in 2011. In 2012, however, no effects on B. cinerea during storage resulted from BCA treatments. The results of the present study suggest that the use of combined BCA treatments only cannot overcome inconsistent efficacies of BCAs against strawberry grey mould under field conditions. Further investigations on the interactions between the BCAs in combined BCA treatments as well as between the BCAs and the pathogen in dependence on multiple factors prevailing in the phyllosphere, however, need to be included to tailor combined BCA treatments with constant efficacies in different years.

Combining biocontrol agents with different mechanisms of action in a strategy to control Botrytis cinerea on grapevine

“…For example, on the strawberry, combined treatments with Ba. amyloliquefaciens, A. pullulans and Beauveria bassiana resulted in improved control of grey mould on fruit, however the effective combinations varied in the trials and single biofungicides were not effective (Sylla et al, 2015). In addition, simultaneous application of incompatible biocontrol agents has sometimes resulted in impaired biocontrol of this disease The use of strategies involving application of each microbial biofungicide at the stage in which it is supposed to be the most effective has never been attempted on the grapevine to combat grey mould, and thus could offer a way of exploiting the different mechanisms of action of various microorganisms without posing problems in terms of their compatibility when used in tankmixtures.…”

“…One of the main practical constraints in the use of microbial biofungicides is their variable efficacy, which is mainly due to unfavourable environmental conditions impairing their survival in the canopy or the intrinsically lower level of disease control as compared to synthetic chemicals. To partially solve these problems, a mix of two or more microorganisms has been proposed (Sylla et al, 2015). Several studies have been carried out on combinations of two or more microorganisms in one treatment (Guetsky et al, 2002;Sylla et al, 2015;Xu et al, 2011) with differing results.…”

“…To partially solve these problems, a mix of two or more microorganisms has been proposed (Sylla et al, 2015). Several studies have been carried out on combinations of two or more microorganisms in one treatment (Guetsky et al, 2002;Sylla et al, 2015;Xu et al, 2011) with differing results. On the other hand, strategies in which different biocontrol agents are applied in sequence throughout the season have received little attention.…”

Biocontrol of strawberry fruit infected by Botrytis cinerea: Effects on the microbial communities on fruit assessed by next‐generation sequencing

“…In this regard, previous studies by Sylla et al. (), Sylla, Alsanius, Krüger, and Wohanka (); Hunter, Hand, Pink, Whipps, and Bending () recently assessed the effects of applying BCAs on the microbial communities of strawberry leaves infected with B. cinerea, using both culture‐dependent and independent methods. These studies detected no significant effect arising from applying a BCA on microbial populations (bacteria and fungi) present on strawberry leaves by a culture‐dependent approach.…”

“…In this regard, previous studies by Sylla et al (2013), Sylla, Alsanius, Krüger, and Wohanka (2015); Hunter, Hand, Pink, Whipps, and Bending (2010) recently assessed the effects of applying BCAs on the microbial communities of strawberry leaves infected with B. cinerea, using both culture-dependent and independent methods.…”