Colletotrichum chrysanthemi によるシュンギク炭疽病の北海道における発生

抄録

Leaf blight and leaf spot symptoms of garland chrysanthemum were observed in Hokkaido, Japan, between August and September, 2013. Four fungal isolates were obtained from diseased leaves. The original symptoms were reproduced after inoculation with the isolates. The conidia on potato dextrose agar were fusiform with dimensions of 6.4–13.1× 3.2–5.3 μm and a length-to-breadth ratio of 2.29–2.62. The appressoria were oblong to ovate with dimensions of 6.1–16.4 × 4.0–8.2 μm. The reverse colony color of the isolates was pale to dark brown. Colletotrichum acutatum species complex-specific primer pairs amplified the expected PCR products from the DNA of the four isolates. β-tubulin-2 gene sequences of the isolates showed 99.9% similarity with that of Colletotrichum chrysanthemi. Based on conidial morphology, reverse colony color, and sequence similarity, we identified the isolates as C. chrysanthemi. This is the first occurrence of anthracnose of garland chrysanthemum in Hokkaido.