1. 1956年11月初旬京都府相楽郡笠置町, 同12月中旬京都市左京区徳善谷, 1957年5月初旬神戸市諏訪山の谷, 1958年11月中旬京都市北区鷹ケ峰において, Quercus glauca THUNB.の葉をひどく枯らす病葉を発見し, 更にその病原菌の純粋分離培養に成功した。2.本病菌の侵害を受けたアラカシ葉は同心輪紋状褐色, 又は灰褐色の病斑を形成し, その上に光沢ある黒褐色の小隆起(分生胞子堆)を散生する。分生胞子は通常有色細胞2つ, 稀に3つを有する。頭部に鞭毛2∿4本を有する。分生胞子の大さは12.4-15.5×5.3-6.2μである。3.本病原菌の菌糸発育最適温度は24℃附近, 最高発育限界温度は32℃より少し高い附近である。湿熱致死限界は50℃10分である。4.本病菌の発育に対する最適pHは4.8∿6.0の間にある。pH10.0附近では全然発育しない。5.本病菌は分離当時馬鈴薯煎汁寒天培地上で分生胞子堆の形成をしたが, その後形成を見ない。ところが紫外線を10分∿90分間照射した場合に, その無照射面に分生胞子堆の形成を見た。此の時は有色2細胞のが少く, 3細胞のが非常に増加していた。6.アラカシ, カシワ, クリ, スギ, チヤ, ビワ等に対する菌糸による接種試験では, 有傷区全部が陽性であつたが, カネ, イチヂク等は有傷, 無傷共に陰性であつた。7.本病害を学界未知のものと見做し, 「輪紋葉枯病」と命名し, その病原菌の学名をPestalotia kasagi ensis YEH et KATSURA sp. nov.とする。The authors founded a new disease of leaf on Quercus glauca THUNB., it caused by Pestalotia sp., and these speciemens were collected at Kasagicho prefectural Kyoto (Nov. 1956.), at Tokuzentani Sakyoku Kyoto (Dec. 1956.), at valley of Suwayama of Kobe (Mar. 1957.), at Takagamine Kitaku Kyoto (Nov. 1958.). This report was described with a morphological, physiological characters and the results of inoculation experiments of the causal fungus. The acervulus was formed in the ring spot on the epydermis of leaves, the conidia have brownish two cells at middle, rarely have three cells, and the flagella have length of almost two times to the conidia. On the potato agar medium the fungus formed hard conidial mass after culture for 20∿25 days only on cultures in short period since the fungus were isolate from the host, however, it did not form at all subcultures on the media used experiment thereafter, but it formed again on the culture of non-radiation side that perhaps received diffuse ray. The diffuse ray occurred when a half part of the cultures were radiated with ultora-violet ray. This result is only once experiment, so it is necessary reexperiment. The optimum temperature of growth to the fungus mycelium on potato agar medium seemed at about 24℃, and leathal temperature of the mycelium was at 50℃ for 10 minutes in water bath. On the pH of the medium the mycelium growth seemed vigorous at 4.8∿6.0. In the inoculation experiments mycelium of the causal fungus showed all positive only wounded leaves by needle on Quercus glauca THUNB., Q. dentata THUNB., Castanea pubinervis SCHNEID., Cryptomeria japonica D. DON., Theae sinensis L., Eriobotrya japonica L., but on the Diospyros Kaki THUNB., Ficus Carica L. showed all not phathogenicity. The authors named "Ring spot blight of Quercus glauca THUNB." and determined its species name as "Pestalotia kasagiensis YEH et KATSURA sp. nov.
