Methods for Preventing and Controlling Pests and Diseases of the Rhododendron mucronulatum and Key Technical Points

1. Leaf gall disease

It generally mainly harms the flower buds, young leaves and new shoots of the Rhododendron mucronulatum. At first, pale yellow semi-transparent round spots appear on the upper surface of the leaves, and afterwards they turn yellow. They also sink in somewhat. This makes the leaves begin to wither and yellow, and they fall early. In severe cases it also causes patches of lesions to form on the petioles, which become very deformed and thickened.

Control method: Before the disease begins, especially when it is putting out shoots and unfolding leaves, some pesticide can be sprayed; if diseased leaves are found they must also be removed immediately. If the disease occurs before sprouting, some pesticide can likewise be sprayed for treatment, and after the disease occurs other pesticides should continue to be sprayed.

2. Leaf spot disease and brown spot disease

Both of these diseases directly affect its leaves, petioles and stems. The lesions on the leaves are round, and afterwards they gradually expand, showing irregular large lesions, and some concentric rings also form; then the lesions gradually change from reddish brown to dark brown, with grayish brown in the middle. Whichever of the two diseases it is, both can make the entire plant completely wither and yellow and die.

Control method: From May to August we can find some corresponding pesticides, mix them in a certain proportion, and then spray once about every 10 days, for a total of 7 to 8 sprayings before and after, and this can control the development of the disease very well. In order to keep some leaves from turning yellow, other solvents can also be added.

3. Sooty mold disease

It really sounds like a very strange disease. Generally, as long as they are damaged, the young branches and leaves will immediately be covered with relatively dense white or pink disease, most of which is caused by aphids.

Control method: First, those diseased leaves must be removed, then some agents should be sprayed on it; in addition, certain spraying techniques must be mastered, so that it will not easily have new disease again.