Effect of Fungicide Application on Lowbush Blueberries Soil Microbiome

Lowbush blueberries (Vaccinium sp.) are perennial crops produced throughout eastern Canada and Maine through management of wild populations. Given the constraints of this cropping system, the application of fungicides is critical to reducing disease pressure and ensuring consistent yields. However, as plant health is intertwined with soil health, it is important to consider the impact of fungicides on microbial communities. To understand the effects of fungicides in this context, bacterial and fungal microbial communities from fungicide-treated plots, as well as untreated control plots (UTG) were analyzed using amplicon sequencing. The fungicides, considered collectively as a combined treatment group (CTG), lead to a loss in fungal richness. One family, Clavariaceae, had an increased abundance under prothioconazole relative to UTG. This finding may be significant as taxa in Clavariaceae have been thought to potentially form ericoid mycorrhizae with Vaccinium. Five functional pathways and 74 enzymes differed significantly in relative abundance between CTG and UTG including enzymes associated with soil nutrient cycles. Most notably, enzymes corresponding to the breakdown of halogen-organic compounds had an increased abundance in CTG, suggesting bacterial fungicide degradation. Some enzymes associated with soil nutrient cycles differed significantly, possibly implying changes to nutrient pathways due to fungicide treatment.