Pseudomonas salomonii, another causal agent of garlic spring rot in Japan

In the 2010s, a sporadic garlic disease in Hokkaido and Kagawa, Japan caused browning and withering of leaves, collapse of aboveground parts, and discoloration of papery sheathing leaves of bulbs and cloves, consistent with the description of spring rot disease. However, the typical rot of storage leaves of cloves was not found. From diseased tissues, bacteria that formed pale-yellow colonies were isolated and demonstrated to be pathogenic on garlic after inoculation and reisolation of the isolates. The gram-negative, aerobic rods with one or two polar flagella were identified as Pseudomonas salomonii based on biochemical and physiological characterizations, PCR assays, phylogenetic analyses, and MALDI-TOF MS analysis. To the best of our knowledge, this study is the first report of P. salomonii in Japan. P. salomonii was originally described in France as the causal agent of café au lait disease of garlic, which can be considered as “a type of spring rot disease that does not rot storage leaves.” Therefore, we are treating the disease caused by P. salomonii in Hokkaido and Kagawa as “spring rot disease”.