1. Physiological diseases

Diseases caused by poor environment and insufficient nutrient elements are called physiological diseases. The whole plant will have obvious symptoms of this disease, and the symptoms are almost similar

This disease has yellowing disease, that is, Rhododendron needs a slightly acidic growth environment. If it is maintained in the north, our soil and water may be alkaline, resulting in leaf yellowing. There is also lobular disease, that is, lack of zinc and manganese, and lack of trace elements. Its leaves will become smaller and thicker, further affecting growth and flowering

The reason for the growth of Rhododendron can be adjusted. For example, if the environment is alkaline, use weak acid soil; If you are short of zinc and manganese, supplement it with zinc and manganese

2. Infectious disease

Diseases caused by pathogenic microorganisms are called infectious diseases, such as leaf spot, anthrax and gray mold. They have an important feature: that is, their symptoms spread from a central point to the surrounding, and the symptoms at the central point are more serious. If not handled, the expanded scope will gradually spread outward

Prevention and treatment methods: this disease also needs to be controlled with drugs, and appropriate drugs should be taken according to the etiology

3. Coal pollution disease

The coal fouling disease is not caused by a single fungus, but because there are stinging insects such as aphids and scabies on the leaves. In the process of stinging and sucking, they leave some excreta on the leaves, which infect the coal fouling pathogen to produce the disease

防治方法：先治虫，将害虫消灭掉，然后采用药剂杀掉煤污病病菌。