Abstract
1. The present paper deals with a study carried out by the writer on some characters of a new fungus which causes an anthracnose of azuki bean.
2. The disease first appears on the under surface of the leaves of the host, as circular, reddish-brown spots. Pale-coloured specks are produced just opposite them, which later become conspicuously brown.
3. Artificial infection with this fungus was secured on azuki bean, cowpea and kidney bean.
4. A certain fungus isolated from cow-pea was found by the writer to be identical with the present fungus.
5. As the causal fungus of this disease is hitherto undescribed, the name of Colletotrichum phaseolorum is proposed for this organism.
Colletotrichum phaseolorum n. sp.
Acervuli which are imperfect and subepidermal rupture and compose irregular or hemisphaerical mycelial mass in which setae surrounded by conidia are formed. Conidia are mostly fusiform, 17-20×3-7μ in size, rarely cylindrical or spindle-shaped. Conidiophores are short; setae are dark brown, one to three celled, 60-110×3-4μ (on Phaseolus radiatus, L. var. aurea, PRAIN.), 60-120×3-4μ (on Vigna Catiang, var. sinensis, KING.), one to several from an acervulus. On potato agar black coriaceous colony is formed. Temperature for growth ranges between 9-36°C, optimum 30°C. It is parasitic on Azuki bean (Phaseolus radiatus, L. var. aurea, PRAIN.), cow-pea (Vigna Caliang, var. sinensis, KING.) and Kidney beau (Phaseolus vulgaris, L.)
Type specimens are collected in Nakahara, Kasuyagun, Hukuoka Pref., June 1922, Oonomura, Tikusigun, Hukuoka Pref., Aug. 1933 on Azuki bean, and in Hakozaki, Kasuyagun, Hukuoka Pref., Sept. 1924, Sept. 1925, Aug. 1933 on cow-pea
