Distribution of Kouyawarabi (Onoclea sensibilis L.) Infested with Pseudomonas plantarii in Yamagata Prefecture and Survival of the Bacterium in Plants

Abstract

We investigated the distribution of Kouyawarabi plants (Onoclea sensibilis L.) infested with Pseudomonas plantarii in Yamagata prefecture and confirmed survival activity of the overwintered bacterium in the plants. Of 239 samples collected from 19 locations in the prefecture, 77 leaf samples were infested with the bacterium. The leaf samples collected from Mogami-machi were highly infested with P. plantarii. High infestation rate of bacterial seedling blight of rice was also observed in Mogami-machi area. The plants were artificially inoculated with the organism and exposed outdoors in summer. In the following spring, the bacteria were re-isolated from the leaves, stems and rhizomes of the plants. The pathogenic bacteria were successfully re-isolated from the overwintered whole plants at the level of 1.2×10⁴-3.4×10⁶cfu/g. Because the organism appears to survive in Kouyawarabi plants under natural conditions in Yamagata prefecture, the plants are considered to be an important infection source of the disease.