Disease and Pest Control of Wool Rhododendron

1. Brown spot disease

The disease may cause the woolly rhododendron to drop its leaves prematurely and wither and turn yellow, resulting in a decrease in its ornamental value. The disease starts at the bottom of the plant and then spreads to the leaves. In the early stage of the disease, a lot of reddish-brown spots will appear, which will then evolve into round shapes, and finally turn into dark-brown polygonal spots. The disease usually occurs in April and May, and the symptoms do not begin to subside until December. However, if azaleas are grown at warm room temperatures, the disease may occur throughout the year. This disease is particularly serious in the rainy season. After the rain, as long as there is still some water left on the leaves when night falls, it may cause the disease. When cultivating artificially, you can try to choose plants with stronger resistance for cultivation, or in winter and spring, pay attention to cleaning up stagnant water and diseased leaves in time.

2. Chlorosis

The main cause of this disease is the lack of iron in woolly azalea, which is also a common disease of azalea. When the plant develops this symptom, the leaves of the plant will turn white and thin. Then, as the disease progresses, the leaves may turn yellow or die. If we want to prevent and treat this disease, we need to choose acidic soil with mountain mud as the cultivation medium for planting at the beginning. When watering, we need to avoid using alkaline water, it is best to use normal rainwater. If it accidentally gets sick, we can irrigate it with black alum water, and use it again every time the leaves become wrinkled, repeating the cycle until it returns to normal.

3. Stem base rot

The main cause of the disease is that during the seedling stage, the workers repeatedly used the cultivation medium, which then produced pathogens, or because the pH value of the medium was too high, or because the wounds were not sterilized in time when the azalea was transplanted. This affects the growth and development of the plant and causes its leaves to fall off. The way to prevent this disease is to disinfect the substrate to be used and adjust its pH to around 5.0 before transplanting the azalea, and be careful not to let the bacteria invade through the wounds during transplantation.