P-446 - A New Botrytis Species Causing Blossom Blight on Blueberries in Michigan

Blueberries (Vaccinium spp.) are an economically important fruit crop worldwide, with Michigan being one of the largest producers of highbush blueberries. Botrytis blossom blight and fruit rot are major diseases affecting growers in the region. While Botrytis cinerea has long been considered the primary causal agent, a recent survey in Michigan identified a novel species as an additional pathogen of blossoms. This study aimed to characterize the new species formally using multilocus phylogenetic analysis (G3PDH, HSP60, RPB2, NEP1, and NEP2), morpho-cultural traits, and fungicide sensitivity. Phylogenetic analyses, using both individual and concatenated gene sequences, placed the new species in a distinct clade closely related to B. fabiopsis, B. caroliniana, and B. galanthina. The isolates exhibited diverse cultural and morphological characteristics on PDA. None of the isolates produced conidia on artificial media but developed typical Botrytis-like conidiophores and conidia on inoculated plant tissues, characterized by hyaline to pale brown, elliptical to ovoid conidia and branching conidiophore. Pathogenicity tests on blueberry tissues, green grapes, and white rose petals confirmed its ability to cause disease, with severity comparable to B. cinerea. Fungicide sensitivity assays revealed that the new species was sensitive to all tested fungicides except cyprodinil. These findings provide new insights into the Botrytis species complex affecting blueberries, management implications for growers, and highlights the need for further diversity studies.