Web-blight of European pear (Pirus communis L. var. sativa de Candolle cultivar ‘Passe Crassen’ and ‘La France’) occurred in Okayama Prefecture, Japan, in July of 1989 and in October of 1993, respectively. The pathogen obtained from infested leaves and sclerotia was identified as Rhizoctonia solani AG1-IB in respect to hyphal anastomosis and culture's types. The common name of Web-blight (“Kumonosubyo” in Japanese) is proposed for this new disease of European pear.
Cystospores of Phytophthora syringae were able to germinate at temperatures between 0-25°C, with an optimum at 15-20°C, but failed to germinate at 30°C. The germ tube attained 50μm long or more after 6hr at 15-20°C. The fungus achieved invasion into lenticel tissue in 8hr at 15°C, when inoculated with zoospores. Under light microscope and scanning electron microscope, it was observed that the infection could occur, not only through lenticels but also through cracks in the cuticle.
A viroid was detected from coleus (Coleus blumei Benth.) in Japan, which was 1 nucleotide larger (249nt) than coleus blumei viroid 1 (CbVd1) and coleus yellow viroid (CYVd), indicating that the viroid was an isolate of CbVd1. Four species of plants in Labiatae (Mentha spicata, Mentha arvensis var. piperascens, Ocimum basilicum and Melissa officinalis), in addition to coleus, were first found to be infected with the CbVd1 without showing any detectable disease symptoms.
A disease of hydrangea was found in Niigata Prefecture, Japan, 1990. Dark green to graysh brown lesions appeared on the leaf blades and blooms of the plants. A species of Botrytis was isolated from those lesions. Conidia were obvoid to ellipsoid, 1-celled, hyaline or pale brown. The optimum temperature for mycelial growth was 20-25°C on PDA medium. The fungus isolated was pathogenic to fruits of eggplant, cucumber, green pepper and tomato. The causal agent was identified as Botrytis cinerea Persoon: Fries. Gray mold of hydrangea was proposed to the disease.