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厌气诱发24～48小时后,大白菜叶柄上可以出现由潜伏侵染的软腐欧氏杆菌(Erwinia carotovora subsp.carotovora)引起的水渍状浸离斑。对病斑的邻近组织(病斑以上1～5毫米)断面进行电镜扫描观察,结果指出,病原细菌最初是潜伏在维管束的导管中的。这些细菌生长繁殖后可以消解螺纹导管间的薄壁部分,最后使螺纹松驰解体,再进一步扩展到邻近的薄壁组织为害,表现症状。叶柄表面没有任何自然孔口,但有自然形成的不规则细微裂痕。细菌在完好的叶柄表面不进行分裂繁殖,但在裂痕附近有繁殖和堆积现象。细菌在叶片上的气孔附近没有明显的聚集和繁殖迹象。有菌的气孔会由于被刺激产生的胶状分泌物而阻塞。
After anaerobic induction for 24 to 48 hours, water-stain leaching spots caused by latent infection of Erwinia carotovora subsp. Carotovora may appear on the petiole of Chinese cabbage. The lesion adjacent tissue (lesions above 1 to 5 mm) cross-sectional scanning electron microscopy showed that pathogenic bacteria initially lurking in the vascular bundle catheter. The growth of these bacteria can digest the thin-walled part of the thread between the catheter, the final relaxation of the thread disintegration, and further extended to adjacent parenchyma damage, the performance of symptoms. Petiole surface without any natural orifice, but there are naturally formed irregular fine cracks. Bacteria do not propagate in intact petiole but multiply and accumulate near the fissure. Bacteria did not show any significant accumulation and reproduction near the stomata on the leaves. Stomata with bacteria can be blocked by the gut secretions that are irritated.