A new isolate of Sweet potato feathery mottle virus (SPFMV) was obtained from Ipomoea batatas in Oita Prefecture in Japan. The symptoms of I. nil infected with this new isolate differed from those of plants infected with the severe (S), ordinary (O), or Tokushima (T) strains of SPFMV. In addition, reverse transcriptase-polymerase chain reaction-restriction fragment length polymorphism (RT-PCR-RFLP) analysis revealed that this isolate was distinct from these other three strains of SPFMV. The coat protein (CP) of this isolate is composed of 313 amino acids, which have over 90% homology with those in the CPs of SPFMV common strain (C), SPFMV-CH2, SPFMV6 and SPFMV-SOR. On the basis of a phylogenetic analysis of the amino acid sequences of the CP, the isolate was classified as a group C strain, among other strains of SPFMV isolated from sweet potato in other parts of the world. This is the first report on the detection of the SPFMV-C strain in Japan, and we have named this isolate SPFMV-Bungo.
Iron coating of rice seeds was originally developed as a seed preparation for direct sowing in flooded paddy fields to reduce the number of floating seedlings and injuries from birds. Here we examined the efficacy of iron coating of rice seeds in the control seed borne bacterial and fungus diseases, because metal ions (e.g., copper and silver) have antimicrobial activity and have been used as a seed disinfectant. When rice seeds inoculated with Burkholderia plantarii, B. glumae or Acidovorax avenae subsp. avenae were coated with iron powder just before seeding, the subsequent seedlings had not developed any disease symptoms by two weeks after seeding. Iron coating was also effective against “Bakanae” disease, brown spot and blast caused by fungi. Four kinds of iron powders were tested, and all were effective against bacterial seedling blight, bacterial grain rot and bacterial brown stripe. Iron coating of rice seeds is advantageous because it can be used for both direct sowing in paddy fields and raising seedlings in nursery boxes. Iron coating to control disease will be developed as a new seed disinfection method to reduce the use of agricultural chemicals.
Rape plants (Brassica napus), which are cultivated for their edible shoots, developed damping-off in Tsu city, Japan, in November 2007. Rhizoctonia solani AG-2-1 was isolated from the diseased seedlings, and the pathogenicity of the isolate was confirmed. Mycelial growth in culture on potato dextrose agar was optimal at 20°C. This is the first report on the disease of rape caused by R. solani in Japan.
Soft rotten fruits of balsam pear were found in orchards of Kanagawa and Okinawa prefecture, Japan in 2004 and 2005, respectively. The causal bacterium was identified as Erwinia carotovora subsp. carotovora according to its bacteriological characteristics. The name soft rot (Nampu byo) was proposed for this new disease.