野外地表で越冬させた本病罹病葉上に春季子のう盤を発見し,子のう胞子の分離培養および接種試験の結果から,これが本病の病原菌Marssonina coronaria (Ell. et J.J. Davis) J.J. Davisの完全時代であることを確認した。完全時代の形態はNannfeldt (1932)の分類に従うとHelotiales, DermateaceaeのDiplocarpon属に一致するが,本属のいずれの既知種とも形態および寄主において異なるので,本菌を新種と認めてDiplocarpon mali Y. Harada et K. Sawamuraの学名を与えた。
The pathogenicity of Pyricularia oryzae and the inhibitory activity of fungicides against it with barley were very comparable to those of rice plant. The use of barley may be convenient for investigating the relation between infection behavior of fungus and disease development.
Partially emerged panicles were frequently observed in the paday fields where the Fusarium leaf spot was severe. Such symptoms in panicles were reproduced by injecting conidial suspension or extract of the fungus into the sheath cavity at the booting stage. Abortive grains also increased highly by the injection.
Chestnut yellow was dsescribed as a graft-transmissible virus disease by Shimada and Kouda (1954). Electron microscopy revealed the presence of possible causal mycoplasmalike bodies in sieve tubes of diseased chestnut leaves.