A Detailed Guide to Common Walnut Diseases and Their Control Methods

Walnut, together with almond, cashew and hazelnut, is known as one of the world's four major dried fruits. It has a wide range of uses and is an economic crop valued both as food and as medicine, and it is grown across an extremely large area in China. However, what affects its growth and yield is pests and diseases, which cause farmers huge losses. So what pests and diseases affect walnut? Below, Qinnong Network brings you the common walnut diseases and their control methods.

1. Walnut powdery mildew

Powdery mildew mainly harms young buds and leaf tips, causing leaves to drop early, and in severe cases it can cause the plant to die. In the early stage, the leaves begin to fade and turn yellow, then gradually the leaves begin to distort, white powder starts to appear, and in the later stage brown or black granules appear within the white powder.

Control methods: When disease is found, promptly remove the diseased leaves and branches and burn them in a centralized manner to prevent spread to other parts, and spray with specialized chemicals for control.

2. Walnut anthracnose

Anthracnose mainly harms the fruit, and it occurs mostly during the rainy season and on plants with weaker vigor. When the disease develops, the pathogen enters through wounds, and brown or black lesions appear at the affected sites. In severe cases the fruit rots and drops off, and the leaves wither and turn yellow.

Control methods: Likewise, remove the diseased leaves and branches and burn them in a centralized manner, strengthen management, prune overly dense plants, improve ventilation, and reduce the growing environment for the pathogen. During the rainy season, promptly spray Bordeaux mixture to prevent the disease. When disease is found, carbendazim or chlorothalonil can be sprayed to eliminate it.

3. Walnut rot disease

Rot disease mainly harms the branches and trunk. If it occurs on the trunk, it is not easy to detect. If a branch is infected, first it loses color and the branch withers, and second there are obvious lesions at the wound, gradually spreading along the branch. In the later stage of the disease, the branch loses water and rots.

Control methods: This disease spreads mainly through spores, so the soil and growing environment should be improved to increase the plant's disease resistance. If the disease is found in time, the lesions can be scraped off and then sprayed with thiophanate-methyl. In winter, the trunk can be whitewashed, which both prevents freezing and prevents the occurrence and spread of this disease.

4. Pests

Walnut has many pests, but as long as they are not large-scale infestations, the harm to the plant is not great. The main pests are: scale insects, longhorn beetles, scarab beetles and various moth species.

Control methods: In spring, collect all fallen leaves or fallen branches and burn them, crush all the eggs found, and when pests occur they can be caught by hand. If that is too troublesome, specialized insecticides can be sprayed to kill them.

The above are the common walnut diseases and their control methods brought to you by Qinnong Network. Walnut pests and diseases are unavoidable, so management should be strengthened and careful maintenance provided; it should not be left to grow freely, otherwise relatively large losses will result.