Coal pollution disease of orchid

The disease can damage Orchid, Dendrobium and Cartland. Because the pathogen is only attached to the leaf surface and does not invade the epidermis, it does little harm to the orchid, but because it is covered with a layer of coal ash on the leaf surface, it affects its ornamental value. and because the cover of the pathogen on the leaf surface affects its normal photosynthesis and thus interferes with its normal growth. The symptom is that both sides of the leaf and the pseudobulb are covered with a layer of coal ash disease spot, its edge boundary is not clear, dark black or gray, the size is uncertain, the general diameter is in 2~5cm. A single spot tends to be round, but it may also be oval or irregular. Often several disease spots are combined to form large irregular spots.

The pathogen of the disease was identified as Gloeodes pomigena. Because the disease mostly occurs in the shady part of the orchid room, measures such as providing sufficient light, moderate heat preservation and promoting faster drying of leaves are helpful to the control of the disease. Wipe the affected area with a damp cloth to get rid of epiphytic germs. (Liu Zhongjian)