First report of Pectobacterium carotovorum and Pectobacterium aroidearum causing bacterial soft rot on curly dwarf pak choy (Brassica rapa var. Chinensis) in Malaysia

摘要: Brassica rapa var. Chinensis (curly dwarf pak choy) is commonly grown in large-scale vertical farming aquaponic systems. In October 2022, soft rot symptoms and dark brown lesions were observed on B. rapa grown in a commercial aquaponic farm located in Perak, Malaysia. The infected stem appeared brown and water soaked. Severely infected plants produced creamy white ooze on the surface before collapsing entirely (Fig. 1A and B). Infected leaves displayed yellow-brown symptoms and eventually rotted (Fig. 1C); the healthy plants were symptomless (Fig. 1D). About 20% of the 20,000 B. rapa plants on the farm exhibited symptoms. Ten randomly selected symptomatic plants, five with infected stems and five with infected leaves, were surface sterilized. Each tissue (1.0 cm 2) was homogenized and suspended in a saline solution. The suspensions were then serially diluted and plated separately on Luria …