Diseases of Dogwood

Dogwood and Angular Leaf Spot

Angular leaf spot mainly harms leaves, causing leaf wilt, leaf fall, and premature aging of the tree. This disease can cause serious damage to Cornus officinalis plants. Generally, the more rainfall there is, the more serious the damage will be.

When angular leaf spot disease occurs in Cornus officinalis, management can be strengthened to improve disease resistance. Fallen leaves under the tree should be removed before budding in spring to reduce the source of infection. 400-500 times of mancozeb can also be sprayed for prevention and control.

Dogwood and Anthracnose

Anthracnose is relatively common and mainly harms the fruits of Cornus officinalis. When the fruits are infected, they initially appear as brown spots, which gradually expand. The fruit may become rigid and fall off or not fall off. The pathogen of anthracnose is spread by wind and rain. The severity of the disease is related to the planting density, terrain and topography. The disease is more serious under the shade of trees, in damp areas with poor drainage, and poor ventilation and light transmission. The peak period of the disease is generally July and August with abundant rain and high temperatures.

Generally, after the fruits of Cornus officinalis are harvested in autumn, the diseased branches should be cut off, the diseased fruits should be picked off, and they should be buried deep in a concentrated area, or more phosphorus and potassium fertilizers should be applied, and field management should be strengthened to prevent anthracnose.

You can also spray 800-1000 times of 50% carbendazim diluted once every half a month for two consecutive times, or spray 1000 times of 25% cypermethrin emulsifiable concentrate or 1000~2000 times of 50% cypermethrin wettable powder for prevention and control.

Dogwood and Powdery Mildew

Powdery mildew mainly harms leaves. Generally, after the leaves become infected, they gradually lose their green color from the tip to the inside, the front side turns into gray-brown or yellowish-brown spots, and the back side has white powdery spots, which are then scattered with small brown to black particles, and finally the leaves dry up and die.

For the prevention and control of powdery mildew of Cornus officinalis, it is generally necessary to plant them at a reasonable density during planting to ensure that the forest is ventilated and light-permeable and the plants are strong, or to spray 1000 times diluted 50% thiophanate for treatment in the early stage of the disease.

Dogwood and Gray Plaster Disease

This disease mainly affects branches and trunks. A circular, oval or irregular thick film is formed on the cortex, resembling a plaster. So, call it gray plaster disease. Occurs on adult plants, usually affecting both living and dead branches. After being harmed, the tree will weaken and even die.

When gray plaster disease occurs on Cornus officinalis, you can apply lime milk or spray 5 degrees Baume lime sulfur mixture on the branches for protection. In the early stage of the disease, spray 1:1:100 Bordeaux mixture for treatment, once every 7 to 10 days, for 3 to 4 consecutive times.