Efficient and Reliable Evaluation of Strawberry Grey Mould Resistance by Inoculation and The Strawberry Endophyte Content after Pseudomonas Fluorescens Application

Garden strawberry (Fragaria x ananassa Duch.) is one of the most important soft fruit crops in Finland. Every year, over ten thousand tonnes of strawberries are produced, but in many cases they are affected by grey mould disease (Botrytis cinerea Pers.). Grey mould disease is absolutely devastating for strawberry, as it can affect up to 80% of the yield. Although chemical fungicides are widely used in controlling the pathogen, there are increasing concerns about its safety and environmental impacts. The use of disease resistant cultivars and biological control agents (BCAs) are two of the alternative methods in controlling grey mould disease. However, the breeding progress of resistant cultivars is limited by the selection methods used, while the BCAs require more characterization. In this study, we evaluated strawberry grey mould resistance by inoculation, and tested the amount of Pseudomonas fluorescens in strawberry after biological control application. Inoculation of strawberry is feasible, efficient and reliable to replace the conventional grey mould evaluation method. Foliage application of P. fluorescens did not significantly change the endophyte content of strawberry, proposing that the use of the bacterium is safe from causing any bacterial contamination