1994年の秋に宮崎県高千穂町で発見したトマトの果実,葉,茎の褐色病斑から分離した菌をPhoma lycopersici Cookeと同定し,トマトの果実,葉,茎等に対する病原性を確認した.これまで,わが国においては,実腐病,茎腐病と輪状斑点病がPhoma属菌によるトマトの病害として記載されているが,いずれの記載も古く,現在のPhoma属とその近縁菌類の分類学的研究と照らし合わせると疑問が生じた.そのため,トマトのPhoma属菌による病害とそれらの病名について検討した.その結果を踏まえて,トマトのPhoma属菌による病害の病名を統一して円紋病とし,その病原をP. destructiva Plowright, P. exigua Desmazières, P. lycopersiciとすることを提案したい.
An attenuated strain of Japanese yam mosaic virus, selected from the fields and referred to as JYMV-M, caused no symptoms on Japanese yam plants throughout the growing season. The purified virus preparation was highly infective, and the virus was easily transmitted by aphids. An RT-PCR-RFLP assay was used in cross-protection tests to discriminate JYMV-M from other severe strains. Pre-inoculation of yam plants with JYMV-M remarkably protected them from infection with severe strains. JYMV-M infection did not affect either the quality and quantity of yam production.
In April 1998, powdery mildew was found on two species of citrus (tankan mandarin and mandarin orange) in Kagoshima prefecture, Japan. White, powdery mycelial colonies appeared on leaves and young shoots. Young leaves specially were damaged severely, infected leaves eventually fell. Conidia were ovoid to cylindric, 25.0-41.6×12.5-18.7(-27.1)μm in size, borne singly on conidiophores erected on aerial mycelium. Appressoria on germ tubes were lobed. Cleistothecia were not observed. On the basis of the morphological characters of the conidial state, the fungus was proposed as an Oidium sp. of the Erysiphe polygoni type.
The pathogenicity and serological properties of Bean yellow mosaic virus (BYMV) isolates from both cultivated and naturalized gladioli in Kagoshima prefecture were investigated. According to the method of Sasaya et al. (1998), 64 BYMV isolates from gladiolus were classified as pathotype I or IV, whereas five BYMV isolates from broad bean were classified as pathotype II. The serological relationships among the BYMV isolates were determined with DAS-ELISA and the improved Ouchterlony double-diffusion test using antisera to isolates S-22N (pathotype I) and S-22C (pathotype IV) originating from a gladiolus source, and Sb-50C (pathotype II) from broad bean. The gladiolus isolates (S-22N and S-22C) differed serologically from the broad bean isolate (Sb-50C).