熊本県玉名郡岱明町と菊池市の桑樹萎縮病は圃場観察において外見的にまたその病徴発見過程において顕著な差異のあることはすでに明らかにされているが,これらは環境条件によって左右されるものではなく,その萎縮病における本質的なものと思考された。このことから両者は病原ウイルスの系統の異なるものとみて,前者を玉名系(Tamana severe strain),後者を菊池系(Kikuchi mild strain)とした。
Taphrina maculans Butlerによるウコン(Curcuma longa L.)斑点病の発生程度は,環境條件と土壌中の感染源の量とに影響されることが示された。葉令により感受性に多少の差異は認められたが,葉は長い間罹病性であって湿度條件に恵まれている間は感染がおこるので,葉令は重要な意味をもたなくなる。病気の発生時期の早さや激しさは,土壌中の有効感染源の密度によって左右される。当地方で8∼9月に多い25∼30°Cの気温と多湿で曇りの天候は本病の激発を助長する。
In a previous paper (Ann. Phytopath. Soc. Japan 25: 187, 1960), the writer reported a virus obtained from cabbage and rape plants showing mosaic symptom, and identified it as cauliflower mosaic virus (CAMV) described by Tompkins (1937). Electron microscopic examination of partially-purified virus preparations revealed two kinds of spherical particles differing in size, about 10∼13mμ and about 50mμ in diameter, respectively. As the larger particles were thought to be the aggregates of the smaller particles, the virus was reported to be spherical particle of about 10∼13mμ in diameter. In the same year, however, Day and Venables (1960) and Pirone et al. (1960) reported that CAMV was a spherical particle of about 50mμ in diameter. As it seemed likely that the writer's former conclusion was in error, re-examination using more purified preparation was made. Preparation made by the purification method already reported was further purified by sucrose density gradient centrifugation after Day and Venables and Pirone et al. Examination of the tube after density gradient centrifugation showed a distinct opalescent band in the middle and a barely discernible opalescent band near the top. The band at the top contained only smaller particles and was noninfectious. In inoculation tests, the middle band showed high infectivity, and electrom microscopic examination revealed the presence of uniformly-sized spherical particles of approximately 50mμ in diameter. The virus was therefore considered to be the spherical particles of about 50mμ, and the writer corrects his mistake in identification of the virus particles reported in his previous paper.