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5 Avocado Tree Diseases and How To Treat Them

Avocados are one of the trendiest and most popular fruits on the market right now. People are discovering the many different health qualities that avocados have and different ways to prepare them, which has led to a spike in their popularity.

Traditionally, avocados have only been grown by mass producers and then sold in grocery stores. Because of how expensive they are and how hard it is to find great avocados, many people are planting their own avocado trees. However, it’s essential that you’re aware of the common avocado tree diseases they’re prone to so you can avoid them.

In this article, we’re going to look at the five most common avocado tree diseases you could run into. Not to worry, though; we’ll also explain how to treat each disease to help you save your avocados!

Closeup of a diseased avocado tree trunk.

What are the Most Common Avocado Tree Diseases?

Avocados are an example of a commodity that produces excellent fruit, but that also comes with definite risks. While avocado trees are fairly hearty plants, they’re prone to certain diseases.

Armillaria Root Rot

Closeup of Armillaria Root Rot, a common avocado tree disease.

This is a fairly common disease, not just with avocado trees but also with many different trees. A healthy avocado tree should have red leaves at a young age, which then change into various colors of green. A healthy avocado tree will have leaves with a solid color and will not appear splotchy. Armillaria root rot will cause the leaves of an avocado tree to turn yellow, and they will fall off of the tree prematurely. A tree suffering from this disease will produce less fruit than it should and die prematurely.

Treatment/Prevention

Armillaria root rot is a fast-spreading disease, and there is no known cure for it. The best way to treat the condition is to keep it from happening in the first place. Here are some things you can do to prevent armillaria root rot from harming your trees.

  • Keep your trees adequately watered.
  • Mulch the area around your trees.
  • Set up fencing or barriers to keep your trees from getting damaged by lawn mowers or weed eaters.

It’s also important to note that this disease can spread from tree to tree. If you have one tree with armillaria root rot, you should remove that tree and as much of the stump and root system as possible.

Verticillium Wilt

Closeup of a black currant leaf infected with Verticillium Wilt, another common avocado tree disease.
Verticillium wilt on black currant leaves.

Verticillium Wilt is another deadly and common avocado tree disease that doesn’t have a cure. The disease manifests itself once again by causing the leaves of afflicted trees to turn brown and fall off prematurely. Verticillium Wilt is one of the easiest diseases to spot, and it’s also one of the most deadly. It’s a fungal disease that grows in the soil that your tree is planted in and infests itself within its root system.

Treatment/Prevention

As previously mentioned, verticillium wilt doesn’t have any known cures, and if you see a tree infected with it, you should remove that tree immediately. However, you can prevent the disease by taking preemptive measures such as watering the tree, pruning it regularly, and providing afternoon shade for it. There are also special fertilizers and additives for the soil you plant your tree in to help prevent verticillium wilt.

While verticillium wilt is a chronic and fatal disease to avocado trees, you can enjoy your tree for as long as possible by doing the preventative things listed above.

Avocado Black Streak

Avocado black streak is another deadly avocado tree disease that causes short-term and long-term damage to avocado trees. Much like the effects of armillaria root rot, avocado black streak causes the leaves of avocado trees to turn yellow and brown. It also causes poor fruit production and often results in smaller and less delicious avocados. Unfortunately, it’s unknown what causes the manifestation of avocado black streak, which means it’s difficult to know exactly what to do to prevent it.

While many of the signs and symptoms of avocado black streak are similar to other diseases, it does have one distinct characteristic. In the later stages of the disease, your tree will start to develop cankers and sores. These cankers develop on the tree’s trunk, branches, and wooded parts and often kill new fruit soon after it grows.

Treatment/Prevention

While it’s unknown what causes avocado black streak or fully how to prevent it, or even how to cure it, there are things you can do to ease the pain. By carefully and regularly watering your tree, maintaining healthy soil near the tree, and reducing as much stress to the tree as possible, you can prolong the life and production of an avocado tree.

Dothiorella Canker

An avocado branch with dead leaves which can be caused by several avocado tree disease including avocado black streak
Dead leaves can be a symptom of several avocado tree diseases.

Dothiorella canker, much like each of the other avocado tree diseases, attacks the leaves of avocado trees and turns them yellow and brown before eventually killing them. However, dothiorella canker also attacks the trunk and branches of the tree and produces their trademark cankers. It causes a reddish sap to seep out of the tree that eventually dries up and turns to a brownish or whitish powdery substance. It can then cause cracking or discoloration in the bark and ends up affecting every part of your avocado tree.

If dothiorella canker infects branches that have already produced fruit, it will cause that fruit to shrivel and dry up. You’ll notice surface lesions and brown streaks on your fruit which eventually lead to plant death. Dothiorella canker truly is a detrimental and terrible disease for avocado trees.

Treatment/Prevention

Luckily, as long as your tree is strong and healthy, dothiorella canker isn’t usually a deadly disease for them. In fact, for strong and healthy trees with proper maintenance, dothiorella canker can be done away with as easy as a common cold in humans. If your tree has dothiorella canker, make sure to cut off any of the affected branches and dispose of them.

You should also get rid of any leaves or fruit that look infected. If you can trim away the dead parts of the tree, and you water and maintain your tree with a good fertilizer, there’s no reason why it shouldn’t fully recover. Water and special fertilizers that are resistant to dothiorella canker are the best solutions to promote a full recovery.

Phytophthora Canker

Closeup of a tree infected with Phytophthora Canker, a common avocado tree disease.

Phytophthora canker is an avocado tree disease that often comes in conjunction with other diseases such as root rot. It usually results because of damage to the roots from a pre-existing condition or from an accident that has cut or broken part of the root. Phytophthora canker in itself usually isn’t enough to kill a tree, but it can make root rot and similar disease more complicated to treat.

A few of the symptoms of this disease include reddish sap seeping out of the tree and cankers of strange colors developing on infected bark. When the root or trunk of the tree is damaged and exposed to the elements, rainwater or unhealthy soil can infiltrate it and result in Phytophthora canker.

Treatment/Prevention

While Phytophthora canker is a nasty and damaging disease, it’s manageable, treatable, and doesn’t spread from tree to tree. To start with, you should apply phosphorous acid to any areas affected by the canker. Make sure that you only apply this treatment to the trunk during the spring when the tree is ready to start its growing season. Otherwise, performing the basics such as proper watering and soil nourishment is extremely helpful. It’s also a good idea to erect barriers around your tree so that you don’t damage it with weed-eaters or lawnmowers.

Frequently Asked Questions

How long does an avocado tree live?

Avocado trees have an incredible lifespan when it comes to fruit producing trees. There are some species in Mexico and Florida that have been producing fruit for 400 years or more. Avocado trees can live hundreds of years if you and your ancestors care for them and maintain them.

How many avocados does the average tree produce?

When properly cared for, an avocado tree can produce as many as 150 avocados per year. However, some species of avocado trees have been known to produce up to 500 avocados per year.

How tall do avocado trees get?

Avocado trees have a wide growth range and can get as tall as 80 feet, or they can be as short as 10 feet. It all depends on what type of tree you have and how well you care for it.

Final Thoughts

An avocado tree with branches showing signs of disease.
Avocado tree diseases often show up in a tree’s branches.

Avocado trees are a great commodity and producer of fruits, but they’re also tough to cultivate and maintain. It’s important that you know the risks to avocado trees before you start your planting process. By making sure that you’re planting in healthy soil and ensuring that you properly protect the tree, you can prevent the most frequently occurring avocado tree diseases.

You should also make sure to keep your avocado tree watered and supplied with adequate shade. As long as you take care of your tree and maintain it vigilantly, an avocado tree can have a long and full life and give you a ton of great avocados!

If you’re a fan of the avocado, then click here to read our other avocado-related blog articles.