Fungal organisms associated with postharvest fruit rots on blueberry in Georgia (U.S.A.) surveyed over two growing seasons

Blueberry is consistently the top fruit crop in Georgia (U.S.A.) for both conventional and organic production, and Georgia leads the U.S. in cultivated blueberry acreage. Among the major concerns for Georgia blueberry growers are postharvest fruit rots caused by fungal pathogens including Alternaria spp., Botrytis spp., and Colletotrichum spp. Postharvest fruit rots can cause significant fruit loss, with severe cases resulting in up to 100% losses in storage. To better understand the primary fungal organisms causing postharvest rots of blueberries in Georgia, a survey was conducted during the 2021 and 2022 growing seasons. In total, 836 fungal isolates were cultured from rotting blueberry fruit collected from 46 different locations within Georgia’s blueberry production region. Isolates were initially identified on the basis of morphology, and genetic identification was subsequently carried out via DNA extraction and sequencing of the internal transcribed spacer (ITS) region from each isolate. Amongst the identified isolates, Alternaria spp., Botrytis spp., Colletotrichum spp., Neopestalotiopsis spp., and Aureobasidium spp. were found to be the most prevalent fungal genera across surveyed sites. Of these, Colletotrichum spp. had the highest overall prevalence, being isolated from sites in all six counties and from a majority of the 46 sites surveyed. Overall, this survey provides valuable information regarding the identity of major fungal groups associated with blueberry fruit rots within Georgia’s blueberry production region.