WILD BLUEBERRY (Vaccinium spp.) - MICROBE INTERACTIONS AND BOTRYTIS BLIGHT MANAGEMENT

Abstract

Botrytis blight is an important disease and a major constraint to wild blueberry (Vaccinium angustifolium and V. myrtilloides) production. The aim of this research was to address the goals of improving yields, improving disease management, production sustainability, and reducing the cost of production partly through the understanding of molecular and polyphenol consequences of wild blueberry microbe interactions. A similar gene expression pattern was observed with both Botrytis cinerea and Serifel® (Bacillus amyloliquefaciens) inoculation. Maximum expression of PR genes varied and depending on the phenotype and the time of sample collection. Most of the flavonoid genes were suppressed at 12 hpi. The expression of flavonoid pathway genes and accumulation of phenolic compounds were phenotype-specific with their regulation pattern showing a temporal difference among the phenotypes. Flower interaction with microbes did not cause any changes in physiological parameters such as photosynthetic rate and stomatal conductance. For disease management, all the tested chemical fungicides reduced disease development by at least 47 % compared to the untreated control. The mean concentration of fungicides was highest in the corolla compared to the gynoecium and the androecium which is suggestive of limited mobility. Fungicides were sufficiently persistent to inhibit B. cinerea at fruit set. No residue was detected in harvested berries. The use of biofungicides provided intermediate levels of disease control with stand-alone applications of biofungicides whereas Switch® in rotation with biofungicides resulted in improved disease control. These results indicate that wild blueberries respond to microbes by the increased expression of PR genes and phenolic compounds, specifically PR3 and PR4. Additionally, two dose application of fungicides is adequate to control Botrytis blight with no residue concerns.