Sainton's disease, caused by the fungus Colletotrichum morifolium Hara, belongs to the subphylum Deuteromycetes in the kingdom of fungi. The fungus exhibits a distinctive feature with small, black, and circular to oval-shaped pycnidia, measuring 55-300 micrometers in diameter. Initially, these pycnidia form beneath the plant's epidermis, and upon maturation, they pierce through it, revealing themselves externally. Surrounding the pycnidia, numerous slender, colorless, and 5-7x2.5-3 micrometers long hyphae emerge, bearing single-celled spores that are also colorless and shaped like a spindle or sickle, ranging from 20-40x3-5 micrometers.
Additionally, scattered between the hyphae and the edges of the pycnidia, you'll find inconspicuous, dark brown, needle-like setae. These setae are equipped with 1-4 septa, with a thicker base measuring 35-110x4-5 micrometers. These structures serve as a key characteristic of Colletotrichum morifolium Hara, the causative agent of the桑炭疽病.
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