Brown spot disease of Polygonum erythrorhizon and its control

Symptoms of brown spot disease of Polygonum erythrorhizome

Brown spot disease is a common disease of Polygonum multiflorum. Generally, if brown spot disease occurs, it will appear on the leaves. Spots will appear on both sides of the leaves. Most of them are circular or quasi-circular patches. In severe cases, black mold will appear, which is the fungal spores.

The brown spot disease of Polygonum erythrorhizome is mostly caused by a fungus commonly known as Polygonum cercosporum. This fungus gathers on both sides of the leaves of Polygonum erythrorhizome, produces spores and continuously divides, making the disease worse.

Conditions for the occurrence of brown spot disease of Polygonum erythrorhizon

The brown spot disease of red polygonum is caused by the fungus Cercospora. For this disease to occur, the first thing needed is suitable conditions for the growth and reproduction of the fungus. Generally, Cercospora will overwinter in the diseased remains of the infected red polygonum in the form of mycelium. In the spring of the following year, as long as the environmental conditions are suitable for the growth of Cercospora, it will begin to grow and reproduce, producing a large number of spores, which will then be spread with the help of natural wind, rain, or watering. Sometimes secondary transmission may occur, increasing the chance of infection of the plant.

Note that in North China and Northeast China, brown spot disease may occur in August.

Prevention and control methods of red Polygonum brown spot disease

Before the brown spot disease occurs, the diseased residues remaining in the plants can be removed in late autumn and early winter to reduce the root causes of the disease and reduce the occurrence of brown spot disease.

In the early stages of black spot disease, drug treatment can be adopted. Spraying 1500 times diluted 50% benomyl wettable powder can have a certain preventive effect.