What is bacterial brown rot in orchids?

1. Damage: This bacterial disease is reported to occur only on orchids. The orchids infected by it include: Cypripedium spp., Paphiopedilum spp., Phalaenopsis spp., Mitassia and Phragmipedium, among others. The disease has been reported in the United States, Japan, and Taiwan, China. 2. Symptoms: At the beginning of the disease, small round to oval water-soaked yellow spots form mostly in the middle of the leaves. As the disease progresses, the color of the lesions changes from light brown to a very dark chestnut brown, and the leaves may take on a greasy appearance. The lesions can spread in all directions and eventually reach the growing point. After entering the growing point, the bacteria spread throughout the entire plant and cause the plant to become a shrunken mass of plant tissue. 3. Pathogen: The pathogen of this disease was identified as Cypripediumsoft rotErwinia cypripedii (Hori) Bergy et al. 4. Control methods: Separate diseased plants from healthy plants, destroy diseased leaves, and spray with Physan at a 2000-3000 times dilution, once a month or as many times as actually needed, which can effectively control the disease. If the plant also rots, soak the pot, the plant, and other items that can be treated in a 2000 times dilution of 8-hydroxyquinoline sulfate or sodium ortho-phenylphenate for 60 minutes to disinfect them. Liu Zhongjian