The occurrence of the soft rot disease of Chinese cabbages [Brassica chinensis] grown in sterilized soil
1998
Togashi, J. (Yamagata univ., Tsuruoka (Japan). Faculty of Agriculture) | Okamoto, K. | Namai, T.
The present study was performed to confirm the occurrence of soft rot of Chinese cabbage raised in sterilized soil. The soil was collected from Yamagata University Farm where chinese cabbages have been continuously grown over many years and was sterilized by autoclaving at 120 degrees C for 2 hours. Then the soil was distributed in clay pots (No.18) buried near to the soil level in the Farm. As control unsterilized soil was used. Chinese cabbages (Brassica campestris, pekinensis group, cv. Matsushimakohai Shin No.6) were seeded on May 9 (spring sowing) and August 5 (summer sowing), 1994. Soft rot bacteria grew exclusively in the rhizosphere and population level of 10(4)-10(6) CFU/g of dry soil was maintained in the sterilized and the unsterilized soil after the heading stage. The soft rot occurred in both soil. Also the soft rot bacteria isolated from the rhizosphere and the diseased tissues of the plant were identified as Erwinia carotovora subsp. carotovora. It was considered that there might be some infection routes such as insect transmission and wind dispersal of bacterial aerosols other than the direct contact of petioles of the plant at the soil which was contaminated with the organism
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