Disease and Pest Control of Rhododendron serrata

1. Brown spot disease

One of the most common diseases of rhododendron is brown spot disease, which usually occurs more frequently in late spring and summer. When the disease first starts, many small brown spots will appear on the leaves of the azalea, and then these spots will gradually expand and turn dark brown. Sometimes some black mold layers will form on the spots on the diseased leaves, eventually causing the diseased leaves to wilt and fall off.

Prevention and control methods: First, remove all infected leaves and burn them to prevent the bacteria from infecting healthy branches and leaves again. Spray the plants with thiophanate-methyl solution to sterilize and prevent the spread of pathogens.

2. Leaf swelling

The disease mainly occurs on young branches and leaves. The transition between spring and summer and between autumn and winter is the peak period of leaf swelling. After becoming infected, the leaves swell and form spherical bumps on the leaves. Sometimes some white powdery substances will appear on the infected parts. In the later stage, the area of ​​the bumps gradually expands, and finally causes the leaves to curl and fall off.

Prevention and control methods: Cut off all infected leaves and branches and burn them before white powder appears, then spray the plants with Jinzhongling for sterilization treatment.

3. Blossom rot

Blossom rot is a disease that seriously harms flowers. Once infected, the color of the petals will fade to a translucent state, and then the lesions will begin to turn brown and gradually rot, causing the flowers to wither and fall prematurely, greatly shortening the flowering period.

Prevention and control methods: Spray with thiophanate-methyl solution for sterilization during flowering, and cut off the remaining flowers as soon as possible after flowering.

4. Tip dieback

The disease is caused by a fungus and is difficult to treat. After infection, the branches, leaves and new shoots will gradually change color and wither, the leaves will fall off, and finally the plant will die.

Prevention and control methods: Disinfect the soil before planting, and pay attention to maintaining the looseness and good drainage of the soil. It can be prevented by spraying with soil bacteria and disinfectant.

5. Pests

Staghorn azalea is often attacked by pests such as aphids, armyworms, short-palped mites, and scale insects. The pests generally gather on the leaves to suck juice, causing infection in the leaf wounds, resulting in the leaves withering and falling off, seriously endangering the growth and flowering of the flowers.

Prevention and control methods: Pests tend to multiply in large numbers in the hot and humid summer. They can be killed with drugs or manually removed. Usually, we should pay attention to the ventilation and air permeability of the breeding environment, spray drugs in time to kill bacteria and insects, and carry out reasonable maintenance and prevention.