Chandler Walnut Tree Diseases And Pests

Chandler walnut is a very popular variety that’s commonly used in confectionery and baking. Besides, the timer is highly valued in the furniture industry in some parts of the world. The kernels can also be used to extract oil or as animal food. Still, like other varieties, a walnut tree disease can significantly reduce the number of walnuts produced. This is why it is important to know what you’re dealing with. 

Keep reading to learn more about walnut tree pests and diseases to be able to recognize them!

Walnut Tree Disease – Causes, Symptoms, and Management

1. Anthracnose 

Anthracnose is caused by the fungus Gnomonia leptostyla. The main symptoms are black and brown lesions on shoots, petioles, and leaves. They fade towards the center and are frequently surrounded by a halo. Large necrotic patches are also very common. These are formed when spots coalesce and are usually located close to leaf margins. Lesions on leaf midribs, petioles, and shoots are sunken and elongated. 

This walnut tree disease can be treated with the proper application of fungicide. Also, some good cultural practices can significantly reduce the severity of it, like spacing trees adequately, avoiding wetting foliage, and removing leaf debris. Tree services Arizona recommend using a nitrogen fertilizer to reduce lesion development and delay leaf maturity. 

2. Armillaria Root Rot

Also known as just root rot, is a disease caused by a fungus Armillaria mellea usually carried by Walnut tree pests. One of the common symptoms is premature defoliation of small, discolored leaves. Additionally, the disease will cause dead branches, clusters of mushrooms at the base, and eventually death if left untreated. 

The fungus will survive in the soil even if the root system dies, and can easily be transmitted from there. However, this disease can be effectively controlled even after becoming established. Make sure to carefully remove dead or diseased plants from the orchard. Also, one of the most effective methods of preventing the disease is to plant resistant rootstocks. 

3. Blackline Disease

Blackline is a virus-caused disease that results in a gradual reduction in tree vigor. Also, the disease can cause dropping and yellow leaves, premature defoliation, and dieback of terminal shoots. Underlying tissue may be discolored and small cracks and holes may be present too. 

The virus is usually introduced from infected pollen, graft wood, or some of the walnut tree pests. Using a virus-free graft is the best way to lower the chances of even developing the disease. Immediate removal will sometimes be required to prevent further spread. 

4. Crown Gall

The main cause of Crown gall is the bacteria Agrobacterium tumefaciens. It causes galls of various sizes on the root crown and the roots themselves. Sometimes, they will even grow on the trunk. Initially, they will show as light-colored bulges and will slowly get darker and larger. Also, they are either hard or spongy and soft. 

The bacterium is usually introduced through wounds on the stressed trees. Tree service Arizona companies recommend planting your trees in well-draining soils and avoid wounding your Chandler walnuts as much as possible. 

5. Walnut Blight

Walnut blight is another disease caused by a bacteria, but a different one – Xanthomonas campestris. It is characterized by small spots on young fruit that rapidly enlarge and get darker. The kernels will shrivel if the infection occurs before shell hardening. On the other hand, if the infection happens later it can cause kernel discoloration.

The main method of controlling this disease is by applying the proper bactericides. They are usually applied once a week during periods of wet weather.


Q: What diseases do walnut trees get?

A: Walnut trees in Arizona are susceptible to diseases caused by fungi, bacteria, and viruses. These are usually transmitted by pests, insects, or pollination. Diseases such as anthracnose, root rot, and crown gall are the most common ones among walnut trees.

Q: How do you treat walnut blight?

A; The primary method of treating walnut blight in Arizona is by applying the proper type of copper bactericides at the right time. Usually, since the disease is caused by bacteria, the owners will spray the bactericide at least once a week during wet periods.

Q: Why is my walnut tree dying?

A: There are many reasons why a walnut tree may be dying in Arizona. Common causes are bacteria, fungi, viruses, or pest infestation. Also, stressed trees are more prone to these infestations, so these are usually caused by the lack of water, sun, or bad soil. 

Local Tree Experts Overview

Usually, it is not that hard to determine what walnut tree disease are you dealing with. Still, since symptoms overlap, you may be confused with what treatment to apply. This is why we recommend having your local arborist with you if you ever notice any strange symptoms on your Chandler walnuts!

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