Photo 2. Basal stem rot caused by Erwinia/Pseudomonas bacteria occurs often in small patches, perhaps indicating spread between adjacent plants.
Basal stem rot
Pectobacterium carotovorum subsp. carotovorum; previously, Erwinia carotovora subsp. carotovora, and Erwinia aroideae. Other bacteria species may also be present in the soft rots.
Worldwide. In warm and wet conditions. In Fiji, it is recorded on Chinese cabbage as Erwinia spp. In Papua New Guinea, Erwinia carotovora pv. carotovora causes a "leaf wilt and petiole base rot" of Chinese cabbage. In Solomon Islands, Erwinia carotovora pv. carotovora is the likely cause of a soft rot of taro corms in storage (see Fact Sheet no. 289), as well as Chinese cabbage stalk rot (unconfirmed). In Federated States of Micronesia, Palau and Marshall Islands, Erwinia carotovora pv. carotovora causes a soft rot of banana (see Fact Sheet no. 214). In American Samoa, Erwinia species are recorded on Chinese cabbage.
Chinese cabbage, and many other plants are hosts, e.g., banana, head cabbage, capsicum, carrot, celery, cucumber, lettuce, and potato.
The bacteria live in the soil. Infections occur through wounds made by insects, and those made at planting or when weeding. The disease usually starts on the underside of the lower leaves close to the soil. A grey watery rot develops rapidly with a strong smell (Photo 1). The rot spreads quickly to the entire plant and it collapses and dies. As the plants die the bacteria are released into the soil. The bacteria are also spread in rain splash. Spread occurs rapidly between plants (Photo 2).
A wet soft rot develops at the base of the leaf stalks. Serious losses can occur in Chinese cabbage crops, especially during hot wet weather. The disease also occurs on head cabbage (Photo 3).
Look for leaves that have wilted, and show grey rots at the base of the stems. This is called a water-soaked symptom. First, the outer leaves wilt, and then the whole plant.
Cultural practices are important in preventing outbreaks of this disease. There is no treatment for the affected crop, but for future crops carry out the following cultural practices:
The variety Pak Choy is especially susceptible to this disease, so try other varieties of Chinese cabbage.
This is not an option for this soil borne disease, unless the problem is associated with soil insects. In this case, use synthetic pyrethroids.
AUTHORS Helen Tsatsia & Grahame Jackson
Photo 3 Queensland Primary Industries and Fisheries, DAF Collection, Queensland, Australia.
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.
This fact sheet is a part of the app Pacific Pests and Pathogens
The mobile application is available from the Google Play Store and Apple iTunes.