First report of Botrytis pseudocinerea causing gray mold on blueberry in North America.
Botrytis cinerea has previously been shown to consist of two sibling species, referred to as Group I and Group II, that can be differentiated by PCR-RFLP analysis of the Bc-hch gene, a vegetative incompatibility locus. Group I has recently been described as a new cryptic species, B. pseudocinerea. Gray mould caused by B. cinerea is a major postharvest disease of blueberries in the Central Valley of California, USA. In 2012 and 2013, blueberry fruit were sampled at harvest from various locations in the region and stored at 0 to 1°C for 5 weeks, and fungi were isolated from decayed fruit. In total, 526 isolates of Botrytis spp. were obtained. Genomic DNA was extracted and PCR-RFLP of a fragment of the Bc-hch gene was performed. Four isolates showed the distinctive restriction band pattern associated with Group I. Based on morphological, physiological and genetic characteristics, the four blueberry isolates were confirmed as B. pseudocinerea. These isolates were considered resistant to fenhexamid. It appeared that this species was present at very low frequency (0.76%) in blueberry fields in California. Previously, B. pseudocinerea has been reported from French, German, and New Zealand vineyards. This is thought to be the first report of B. pseudocinerea causing gray mould in blueberry in California and in North America.