Bacterial brown spot

Distribution: Worldwide; more common in Asia, USA.

Pathogen: Pseudomonas catleyae, Pseudomonas Cypripedii, etc.

Parasitic: It is very extensive, mainly including Ascocentrum, Aerides, Cattleya, Cymbidium, Cypripedium, Dendrobium, Gastrochilus, Paphiopedilum, Phalaenopsis, Vanda and so on.

Symptoms: Soft, water-like spots on leaves that develop into well-defined, depressed, brown or black spots. In Phalaenopsis, the spot is blister-like, rapidly expanding, united, and surrounded by a yellow or light green halo. Usually the disease develops rapidly and causes the death of the entire plant.

Prevention and control: pay attention to ventilation and environmental hygiene, avoid pouring water, because damp and warm environment is most likely to cause this disease. If diseased plants are found, infected organs or whole plants can be cut off according to the situation, and then sprayed with 0.5% Bordeaux mixture or 200mg/L agricultural streptomycin or soaked in 0.1% potassium permanganate solution for 5 minutes, washed and dried before planting. (Chen Xinqi, Ji Zhanhe)