First occurrence of blueberry anthracnose caused by Colletotrichum nymphaeae (an additional pathogen) and Colletotrichum fioriniae in Hokkaido.
Blueberry fruit rot accompanied by orange conidial mass was found in Hokkaido, Japan in August 2013. Two fungal isolates, one forming reddish reverse colonies and the other gray colonies, were obtained from diseased blueberries. The conidia of the former on potato dextrose agar were oblong to fusiform with dimensions of 7.4-12.6×2.8-4.6 µm and a length-to-breadth ratio(L/B)of 2.74. Those of the latter showed dimensions of 9.4-16.4×3.3-4.8 µm with an L/B of 3.10. The appressoria of the former were oblong to ovate with dimensions of 7.3-13.9×4.1-7.1 µm and those of the latter showed dimensions of 7.5-14.4×4.5-7.3 µm. The Colletotrichum acutatum species complex-specific primer pair amplified the expected PCR products from the DNAs of the two isolates. On the basis of conidial morphology, reverse colony color, and partial nucleotide sequence of the β-tubulin-2 gene, we identified the red-colony and gray-colony isolates as Colletotrichum fioriniae and Colletotrichum nymphaeae, respectively. The original symptoms were reproduced by inoculating blueberries with the isolates. The disease is new to Hokkaido, and C. nymphaeae was found to be a new pathogen of the disease in Japan; therefore, we propose to add it as the pathogens of blueberry anthracnose.