Bacterial disease of orchid: Brown rot

1. Harm: this bacterial disease is reported to occur only in Orchidaceae, and the orchids infected by it include Cymbidium, Papiliopsis, Mitassia, Phragmipedium and so on. The disease has been reported in the United States, Japan and Taiwan.

2. Symptoms: at the beginning of the disease, there are round to oval water-stained yellow spots in the middle of the leaves. With the development of the disease, the color of the spot changes from light brown to dark chestnut brown, and the leaves may have an oily appearance. The disease spot can develop in all directions and finally reach the growth point. After entering the growth point, the bacteria develop to the whole plant and turn the plant into a dry pile of plant tissue.

3. Pathogen: the pathogen of the disease was identified as Erwinia cypripedii (Hori) Bergy et al.

4. Control methods: separate diseased plants from healthy plants, destroy diseased leaves, spray Physan 2000-300O liquid, use it once a month or determine the number of times according to actual needs, can effectively prevent and cure. If the plant is also rotten, the plant pot and other things that can be treated are soaked in 2000-fold solution of 8-hydroxyquinoline sulfate or o-phenylphenol sodium for 60 minutes.

Liu Zhongjian