Five Common Diseases of Avocado Trees

Thanks in part to the current popularity of avocados, many homeowners have begun growing their own avocado trees.

This is a great way to keep your kitchen stocked with the delicious and nutritious fruits, but the trees themselves are also quite desirable. They not only exhibit a handsome growth habit, but they also produce dense foliage, which can provide excellent shade. And because avocados grow well in Southern California, they’re likely to become even more common over time.

Diseases of Avocado Trees

Unfortunately, while avocado trees can provide substantial value to the average suburban property, they are susceptible to a variety of diseases. This includes generalist pathogens that afflict a variety of species as well as more targeted threats, which tend to harm avocado trees more than others.

We’ll talk about five of the most common diseases of avocado trees below and describe some of the most obvious symptoms they cause. This should help you spot the first signs of trouble so that you can get your trees the help they need.

1. Armillaria Root Rot

Armillaria root rot is a widespread disease that afflicts a number of tree species. In avocado trees, it generally manifests as reduced vigor and overall, generalized decline. The leaves of afflicted trees will usually look yellow, and many will fall off the tree prematurely.

2. Verticillium Wilt

Verticillium wilt is one of the easiest ailments to identify for avocado trees. Typically, the first obvious symptom involves the sudden wilting of foliage on one side of the tree. The leaves will quickly turn brown, but they won’t fall off the tree for some time. If any branches are removed from the tree, be sure to inspect them for gray-colored streaks, as this is another symptom that often suggests verticillium wilt.

3. Avocado Black Streak

Avocado black streak is a serious disease that often kills trees outright. In the early stages, the disease is often characterized by poor fruit production, blotchy markings on the leaves, and a general yellowing of the tree’s foliage. As the disease progresses, cankers often form on the trunk and branches, and new growth tends to die shortly after appearing.

4. Dothiorella Canker

Dothiorella canker is a relatively minor fungal problem that occasionally afflicts avocado trees. It usually begins with the formation of cankers on the trunk and primary branches. Over time, these cankers will eventually begin to discharge a white powder, and the bark on the trunk will begin to split and peel away from the tree. Over time, this disease often makes trees appear dead or nearly so but might recover with proper treatment.

5. Phytophthora Canker

Phytophthora canker is another serious disease that affects avocado trees. But while some trees die shortly after contracting the disease, others linger for months or years before succumbing. Phytophthora canker usually manifests as a series of lesions or cankers on the lower trunk. These dark-colored cankers often begin to leak a reddish sap-like fluid, which is often described as having a fruity odor. This disease often afflicts trees that are also infected with avocado root rot, which makes treatment particularly complex.


Fortunately, avocado trees are relatively hardy, and they can often survive pests and disease with proper treatment. Just remember to act quickly if you suspect that your avocado trees have contracted an infection – prompt action is the best way to give your trees the best chance of survival.

If you think that your avocado trees are suffering from one of the diseases discussed above (or they are failing to thrive for any reason), give your friends at Evergreen Arborist Consultants a call. One of our ISA-certified arborists will visit your property, inspect your trees and provide actionable advice for addressing the issue.