Forestry 101: Everything to Know About Diseased Trees

Trees offer us various things. It’s something to keep us out of the rain, shade from the summer heat, color, privacy, and overall just being there. Like any other living thing, however, even trees can get diseases. Since diseased trees are plants, they can also die if not taken care of.

Various types of diseases can affect trees, and some might not even be too severe and might just be a nuisance, but others can be very destructive to trees. Trees with diseases can also help spread that disease to others if not treated. Additionally, it can still be very harmful to the trees’ health even if it’s already treated. For this reason, you need to be proactive in identifying these diseases.

This article will discuss diseased trees and what you can do about them. Read on below to get started.

Common Diseases in Trees

Pine Needle Diseases

Pine needle diseases are the single most dangerous disease to pine trees. However, only pine trees are affected by it, and there are two varieties of pine needle diseases. One of them is called the eastern white pine needle blight, which is more common. The other is called pitch canker, and it is less common. There are some differences between the two, but for the most part, the symptoms are similar.

Hardwood Leaf Diseases

The most common diseases that affect hardwood trees are various leaf diseases. They won’t kill the whole tree, so the damage might not be fatal, but it can weaken it considerably. It’s not an excellent way to have a tree die, but it is better than having the whole tree permanently damaged. Examples of leaf diseases include leaf scorch, leaf curl, leaf drop, leaf blisters, and leaf spots.

Stem Diseases

Stem diseases are considerably less common, but they can be more devastating because they affect the tree’s foundation. Some examples are cankers and galls. These are usually caused by fungus, bacteria, mites, or viruses. The infection will cause swelling on the stem, which can be very harmful.

Root Diseases

As the name suggests, these diseases affect the tree’s roots and cause the death or harm of the roots. They are most common in older trees, and they can spread. These are also some of the hardest to remove, and they can cause permanent damage to the tree if they aren’t treated.

Symptoms of Diseased Trees

Even if you are not a trained arborist, you can quickly identify some of the common symptoms of a diseased tree. We’ll go through some of them below.

  • Some plants are not affected and may provide good contrast.
  • The sapwood of the tree might turn reddish.
  • The tree’s roots will start to rot, and the woody area of the tree will begin to diminish.
  • The tree will lean and tend to break.
  • The tree starts to shrink.
  • The tree will have a hard time growing new leaves.
  • The inner bark will change color.
  • The outer bark will become loose and have cracks.
  • The inner bark will become discolored.
  • The tree will become sticky, which is how easily identified a diseased tree is.
  • The tree has a lot of dead branches, but the top of the tree still looks good.
  • The branches look withered, but the top of the tree is still in excellent condition.
  • The tree has brown or black spots.

After you’ve confirmed that the tree is showing symptoms, it is time to identify those symptoms. It’s a good idea to confirm it with a professional, but it’s also good to know what to look for so you can spot a diseased tree yourself.

Unfortunately, many people think that a diseased tree is an unhealthy tree and they can be dead wrong. Some trees are perfectly healthy, and they look like they are diseased. If you want to tell how bad a tree’s health is, you’ll need an expert to confirm it for you.

What You Can Do

There are things you can do to help treat a diseased tree. As a matter of fact, it’s easier to treat them than it is to treat other organisms that are affected by the disease. There are various treatments available for a diseased tree, and you can choose from them. You will need to consider how severe the disease is and the tree’s condition before deciding on your treatment.

If the disease is severe, you should have a professional handle the treatment. They have the right equipment to handle the treatment, so you don’t have to worry about it.


When you have a big tree on your property, you need to ensure its health. You will be able to identify diseased trees and what you can do about them. There are many things to consider when you are dealing with diseased trees, so having a professional do it is a good idea. This will ensure your trees stay healthy and won’t have any problems.

Need help? We’re experts in timber management. Contact us today.

Share this!