A new bacterial disease of bellflower was found in Mie Prefecture, Japan, in the autumn of 1997. Brown spots on leaf blades and necrotic stripes on leaf petioles characterized the disease. Bacterial strains from bellflower induced symptoms the same as those on naturally infected plants and also induced the same symptoms found with lettuce bacterial varnish spot disease caused by Pseudomonas cichorii. On the basis of bacteriological characteristics, the bacterium was identified as Pseudomonas cichorii. This is the first report of bacterial brown spot disease of bellflower.
Gray mold was found on petioles and stems of Mitsuba (Cryptotaenia japonica Hassk.) growing in hydroponics in the summer of 1998. A Botrytis species was isolated from the infected plants. Based on the morphology and the growth temperature, this fungus was identified as Botrytis cinerea Persoon: Fries. Because a cooled nutrient solution was circulated in the hydroponic system in summer, temperature at the base of the Mitsuba plants was kept on rather lower temperature in this season. Cool weather, therefore, is required for this disease to occur during the season.
Several strains of Burkholderia glumae formed yellowish orange colonies on agar plates containing saccharides, such as glucose, ribose and arabinose. These colonies formed at 35°C or 30°C turned violet immediately after exposure to ammonia. This phenomenon was observed only in these pigment-producing strains, but not in other plant pathogenic bacteria, indicating that these strains can be used for monitoring B. glumae in ecological studies.
The full nucleotide sequence of the S RNA segment of Melon yellow spot virus (MYSV) was determined to be 3232 nucleotides long and to have every feature of the S RNAs of tospoviruses reported so far. From an amino acid sequence comparison of nonstructural proteins (NSs), MYSV is most closely related to two tospoviruses in serogroup IV. MYSV had nucleotide and amino acid sequence identities over 96% with Physalis severe mottle virus in all regions of S RNA except in an intergenic region and in deduced open reading frames, including that on complementary strand RNA.