We all know trees can be affected by disease. But, did you know that if left untreated disease can spread throughout an entire tree and even to nearby trees? In severe cases, disease can kill off a tree. However, identifying diseased trees is not always easy. Diseased trees should always be treated by professionals, as it is not easy to tell to what extent the tree is damaged. Early detection can also get control of a situation before it spreads and has a wider impact on nearby trees.
Different Types of Tree Diseases
Fungi is the main culprit when it comes to most tree diseases. This microorganism comes in many forms and is typically involved in the decomposition of organic matter. When exposed to a tree’s vascular system, either at the roots or if the bark is damaged allowing the fungi access to the interior, disease can set in.
How to Identify Common Diseases
The easiest way to identify common diseases is to look for changes in the appearance of a tree. Changes to the foliage are a good indicator that something is wrong. The types of changes to look out for include foliage that does not fill in, leaves that change color or drop out of season, and any damage to leaves, such as holes or spots. Changes to the color, consistency and even presence of bark are also an indication that there is a problem. Let’s look at some of the fungal diseases common to trees:
Armillaria Root Rot
Armillaria root rot is caused by a variety of different fungi. This disease is named such because all of the different strains of fungi belonging to the genus Armillaria. Trees with Armillaria root rot may feature light or bleached wood, stunted leaves, branch dieback and even chlorosis, which is caused when not enough chlorophyll is produced and leaves and needles lack pigmentation. Conifers may produce excess resin. When Armillaria root rot is present, it is important to contain it and prevent the spread of the fungi. All infected material must be removed.
Another fungal disease is Verticillium wilt. This fungus lives in the soil and it enters plants through the roots and spreads throughout the entire tree. The leaves of trees affected by Verticillium will turn red or yellow and eventually brown, and wilt, curl and drop off. Twigs and branches will also experience dieback. Verticillium wilt can be controlled by maintaining a rigorous fertilization and water schedule. It is also necessary to remove sick areas.
Thousand Cankers Disease
Walnut twig beetles can become carriers of Geosmithia morbida fungus and imbed the fungus in specific types of walnut trees. As the fungus germinates and grows, it causes Thousand Cankers disease. This disease is marked by a rapid spread of dark colored, oval-shaped cankers. Tree cankers are areas of dead bark. In later stages of Thousand Cankers disease an amber discoloration forms on sections of dead bark.
Another fungus based disease is Dogwood Anthracnose. The early stages of Dogwood Anthracnose can be observed when leaves in the lower crown develop tan spots with purple rims. Necrotic, or dead spots eventually form on the leaves. These symptoms will spread throughout the tree. Cankers will develop on twigs and branches, which will eventually lead to dieback. If left untreated cankers will form at the base of dead branches, while bark will swell and split.
There are a variety of fungi that cause mildew, and often they are host specific. For instance, a mildew that forms on an oak tree may not impact other tree species. Mildew is found when the humidity is high, and can be identified by white patches or spots that form on leaves. To prevent the spread of mildew it is necessary to remove infected leaves. Dense canopies are more susceptible to mildew, so increasing airflow by pruning a tree will help prevent recurrences.
Hazards of Having Sick Trees
Diseased trees may lose limbs, or the entire tree could fall. Falling trees obviously pose a safety risk to people and pets, but may also damage homes, vehicles, and property. Oftentimes, if left untreated one sick tree can infect others. In severe cases, an entire grove or yard full of trees can become infected and be at risk.
How to Treat Diseased Trees
In most instances, diseased trees can be treated by removing damaged branches or sections. In extreme cases, it may be necessary to take a diseased tree down. When a fungus or insect is to blame it can be more challenging to eradicate the disease, which makes early detection all the more important.
Consulting a professional is the best course of action if you think you may have diseased trees on your property. A trained arborist can evaluate the trees and determine what the problem is and how best to resolve the issue. At Precision Tree Service our team is highly trained in how to identify and treat diseased trees. Contact us today and we can help you and your trees be more healthy!