The red turnip, Brassica campestris L. (rapifera group), “cv. Atsumi-kabu” grown in burnt fields in Atsumi-machi, Yamagata Prefecture, Japan, showed wilting followed by yellow discoloration of leaves from September to October in 1986. A few small, water-soaked soft-rot lesions were formed on the bases of leaf petioles and the roots. They gradually developed, and finally whole plants decayed. Soft-rot Erwinia-like bacteria were predominantly isolated from the diseased plants. Pathogenicities and bacteriological characteristics of the isolates were identical with those of Erwinia carotovora subsp. carotovora. From these results, the present symptoms on the red turnip, “Atsumi-kabu”, was suggested to be caused by E. carotovora subsp. carotovora. This is the first report on the occurrence of soft rot on the vegetables in burnt fields in Japan.
The causal bacterium entered lemmata and paleae through stomata, and multiplied in the intercellular space of the parenchyma. Stomata are mainly open on the inner surface of lemmata and paleae, few on outer surface of lemmata, and they are connected each other through the intercellular space of parenchyma. This infection site does not seem specific phenomenon with regard as in case of Erwinia herbicola. The bacterial grain rot caused by Pseudomonas glumae and the bacterial seedling blight caused by P. plantarii followed this infection pattern to the rice grain. It is suggested that the seed-borne bacterial disease of rice generally follow this course of life cycle. Browning occurred only on the inner surface and the parenchyma of the palea affected with E. herbicola, and is suspected to be one of the defensive reaction of the palea against E. herbicola.