Changes to Soil Microbiome Resulting from Synergetic Effects of Fungistatic Compounds Pyrimethanil and Fluopyram in Lowbush Blueberry Agriculture, with Nine Fungicide Products Tested

Authors: LLOYD, AUSTIN - Dalhousie University; PERCIVAL, DAVID - Dalhousie University; LANGILLE, MORGAN - Dalhousie University; Yurgel, Svetlana

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2022
Publication Date: 2/6/2023
Citation: Lloyd, A.W., Percival, D., Langille, M.G., Yurgel, S. 2023. Changes to Soil Microbiome Resulting from Synergetic Effects of Fungistatic Compounds Pyrimethanil and Fluopyram in Lowbush Blueberry Agriculture, with Nine Fungicide Products Tested. Microorganisms. 11(2):410. https://doi.org/10.3390/microorganisms11020410.
DOI: https://doi.org/10.3390/microorganisms11020410

Interpretive Summary: Wild blueberries are an economically important crop in Atlantic Canada, Quebec, and Maine. The fruit is produced by managing naturally occurring plant populations. These plants have an intimate relationship with the soil microbiome and depend on it for their health and productivity. Fungicides are an important tool in fighting disease in the crop but pose potential risks to soil health. In this study, we used genetic markers to determine the effects of nine fungicides on the bacterial and fungal communities associated with wild blueberries and to study whether these effects led to significant outcomes for the plants themselves. One fungicide, Luna Tranquility, a combination of two active ingredients (fluopyram and pyrimethanil), was found to cause significant changes to bacterial and fungal soil population. Additionally, our research suggests that Luna Tranquility may lead to increased bacterial degradation of fungicide compounds, potentially reducing its effectiveness. The fact that Luna Tranquility led to significant changes to the soil ecosystem raises the possibility that its long-term use may have important ramifications for soil health.

Technical Abstract: Lowbush blueberries (Vaccinium spp.) are a crop of economic significance to Atlantic Canada, Quebec, and Maine. The fruit is produced by the management of naturally occurring plant populations. The plants have an intimate relationship with the soil microbiome and depend on it for their health and productivity. Fungicides are an important tool in combatting disease pressure but pose a potential risk to soil health. In this study, amplicon sequencing was used to determine the effects of nine fungicides on the bacterial and fungal microbiomes associated with lowbush blueberries and to study whether these effects are reflected in crop outcomes and plant phenotypes. One fungicide, Luna Tranquility, a combination of fluopyram and pyrimethanil, was found to impart significant effects to fungal and bacterial community structure, fungal taxonomic abundances, and bacterial functions relative to control. The two fungicides which contained fluopyram and pyrimethanil as single ingredients (Velum Prime and Scala, respectively) did not induce significant changes in any of these regards. These results suggest the possibility that these microbiome changes are the result of the synergistic effect of fluopyram and pyrimethanil on soil microbiomes. While these results suggest a significant disruption to the soil microbiome, no corresponding changes to crop disease levels and yield were found as a result of Luna Tranquility treatment. Ultimately, the majority of the fungicides analysed in this trial did not produce significant changes to the soil microbiome relative to the untreated group However, one of the fungicide treatments, Luna Tranquility, did produce significant changes to the soil ecosystem that could have longer-term effects on soil health and its future use may merit additional investigation onto its ecotoxicological properties.