Abstract
Eight hundred and thirty-nine isolates of soft rot bacteria were collected from 17 kinds of diseased vegetables in the Tsuruoka District, Yamagata Prefecture, Japan, in 1984-1986. Their sensitivity to 10 phage isolates tentatively named as a to j was then tested by means of the drop method. The phages, which were collected from soft rot lesions of the plants in the same district in 1984, were different each other in the host range. The phage-sensitive isolates of the bacteria were classified into 10 groups tentatively named as A to J according to the bases of susceptibility to the phages. Some of the bacterial isolates showed a different reaction to the phages from that of the isolates belonging to groups A to J. In 1984, 60 (22.0%) out of 272 isolates were sensitive to the phages and 43 of them belonged to these 10 groups (A-J). In 1985, 119 (43.1%) out of 276 isolates were sensitive to some phages and 113 of them belonged to 5 groups. And in 1986, 112 (38.4%) out of 291 isolates were sensitive to some phages and 106 of them belonged to 7 groups. Though there was no predominant group in 1984, the isolates belonging to group G occurred predominantly in 1985 and 1986. They accounted for 84.1% and 74.1% of the phage-sensitive isolates, respectively. Also, there was no definite correlation between the percentages of the phage-sensitive isolates, predominant group of the soft rot bacteria and species of the plants.
