Leaf spot caused by Cercospora Fungi

Orchids harmed by the disease are: Cartland, Dendrobium, Laililan, Orchid, Oncidium and Orchid and so on. On Dendrobium, the symptoms are that tiny and sunken yellow disease spots appear on both sides of the leaves, and the spots quickly develop into round to oval or irregular shapes, dark brown to black, and some combine to form irregular spots. If the disease is serious, or at the base of the leaves, the leaves may fall off, and the conidia or fruiting body structure of fungi will be produced on the older disease spots and fallen leaves. It will become the source of infection of susceptible plants in the future.

The pathogen of the disease is Septoria selenophomoides. Make a 1000-fold solution with 50% wettable powder and spray with a little wetting agent, once every two weeks for a total of 3 times, and then use the medicine once a month if necessary. Fumi and chlorothalonil 2787 can also be used to protect plants against bacterial infection, the concentration of which is 8OO times solution. For Dendrobium orchid, the above two kinds of chemicals should be used one month before natural shedding, and all symptomatic fallen leaves should be destroyed centrally. In other seasons, the above two kinds of pesticides are good for both deciduous and evergreen Dendrobium. (Liu Zhongjian)