Claviceps yanagawaensis TOGASHI distributes very commonly in the Zoysia-growing region of the northern range of Honshu and probably far to the southern, occurring at least in Nagano Prefecture. In certain range, 40% or more of the Zoysia spikes are attacked by the fungus, the ergot yield being estimated as 150 g to 400 g in 400 square meters. In the northern districts, the blooming period of Zoysia japonica extends from the middle of June to the first 10 days of July, during which high moist weather continues for several days and air temperature mostly fluctuates between 15° and 20°C., the meteorological conditions are apparently quite favorable to the formation of sphaeridia and to the infection of the fungus. The sclerotia mature at the end of September, showing the mean values of 6.35±0.05 mm in length, 0.81±0.003 mm in width, and 2.26±0.02 mg in weight. Generally, one sphaeridium is produced from one sclerotium with a variation of 1-7. The biometrical means of the sphaeridia, perithecia, asci, and ascospores are 1.08±0.01×1.22±0.01 mm, 244.9±1.8×130.6±1.4μ, 145.3±1.1×5.15±0.03μ, and 124.4±0.8×1.32±0.02μ, respectively. The conidia are very variable in shape, showing ellipsoidal, ovoidal, spindle-shaped, etc., colorless, and measure 11.03±0.05×5.35±0.02μ.
A disease of Hibiscus syriacus interested the author, since the causal fungus has been thought to belong to a rarely known, but an important fungal genus. The disease spots appear on the leaves first in summer, but it becomes severe in autumn. The spots are subcircular, at first light brown, discolor to dark brown, then greyish brown. It is caused by a fungus Corynespora Hibisci nov. spec. Since the genus Corynespora was established by GÜSSOW in 1906, it has long included one species only. In some cases even the existence of the genus was doubted. C. Hibisci, the causal fungus of the brown spot disease, is the second species in this genus. Isolation and inoculation of the causal fugnus has been carried out and the pathogenic nature of this fungus has been ascertained. Germ-tubes are sent from the distal or proximal end of the conidia. At the tip of the germ-tubes an appressorium is formed, and an infection hypha is sent, which penetrates the epidermis at the anticlinal wall of the epidermal cells. Soon a necrosis occurs in the host tissues. A detailed comparison of the causal fungus with related fungi and its technical description have been given.