Leaf spot disease can be caused by fungi of the genus Diplodia

This disease was found on Cattleya in the United States. Its occurrence is not severe, and it usually appears on weak-growing or injured leaves. At the beginning of infection, small yellow areas appear on the underside or upper side of the leaves. As the disease progresses, the diseased areas turn brown and finally become black, oily-looking areas. On older lesions, black raised fungal fruiting structures appear, which are the pycnidia of the pathogen. The pathogen was identified as Diplodia laeliocattleyae. Because this disease is not often found, no effective control measures have yet been found. Generally speaking, the only option is to remove and destroy all diseased leaves to reduce the source of infection. Considering that infection of other plants by Diplodia fungi occurs through wounds, fororchidsthe same may also be true, so care must be taken to avoid injuring the plants. (Liu Zhongjian)