Symptoms and Control Methods of Cattleya Leaf Spot Disease

① Harm: The host plants that this unidentified species of Cercospora fungus can infect include the following genera: Brassavola, Epicattleya, Epidendrum. ② Symptoms: The disease is characterized by slightly sunken, purplish-black minute lesions on the underside of the leaves, generally no more than 1mm in diameter. These lesions result from the pathogen entering through the stomata on the leaf underside. Often all leaves are affected, producing many discrete minute lesions, greatly reducing the vigor of the diseased leaves. The corresponding areas on the upper leaf surface appear pale yellow-green. Usually the oldest leaves are most severely infected, though leaves that are not yet fully mature may also be affected. Severely diseased leaves will drop off. ③ Control methods: Prepare a 1000-fold solution using benomyl 50% wettable powder, add a small amount of wetting agent, and spray. Apply once every 2 weeks for a total of 3 applications. Thereafter, if necessary, spray once a month. (Liu Zhongjian)