Sick or Distressed Trees
Written by Matt Bertone, edited by Minda Daughtry
Trees are everywhere in North Carolina and provide numerous benefits, including shade, food for animals, and resources for humans. Although long-lived, trees are not immune to injury or disease.
The first step is knowing what a healthy individual of a particular species looks like.
Typically, trees have a full canopy of leaves or needles that are the correct size, shape, and color for that species or variety. While most trees have green leaves or needles, some varieties are paler or yellow, so note that even though it may look unhealthy, this is actually typical for that species or variety.
There are several symptoms of unhealthy, stressed, or dying trees. These may include:
- leaf or needle color changes, typically from green to yellow to brown, either with leaf drop or brown leaves remaining on the tree
- epicormic sprouts, (also known as “suckers” or “water sprouts”, growth that emerge from dormant buds along the trunk and branches of a tree)
- adventitious growth (The bud occurring elsewhere on the plant (such as on trunks, roots, or leaves) except from the leaf axils, stem tips, and plant apices)
- bark splitting, cracking or peeling
- growth of fungi or
- the presence of wood-boring insects
Overall discoloration of leaves or needles of an unhealthy tree is often a sign of something happening lower down, that is in the soil or the root system. There are various problems that can cause this. These issues at the base of the tree cut off the supply of nutrients and water to the top, which causes the color change in the leaves and the eventual death of the tree. Often times, these issues are very difficult to diagnose on your own, so it’s best to call a specialist or have the NC Plant Disease and Insect Clinic identify or diagnose those issues for a particular tree specimen.
These problems include:
- freeze damage
- physical damage to the base of the tree
- girdling roots
- soil quality issues
- root disease
Another symptom of an unhealthy or stressed tree is called dieback. This is where numerous twigs and branches lose their leaves and the canopy becomes thin. Dieback can be a result of stress or issues in the soil or roots, but also sometimes individual branches and twigs are affected by cankers or physical damage to them. This may be seen where multiple branches are healthy and others are not. The best way to find out which is which is to follow the unhealthy dead twigs and branches down to where they transition to the healthy tissue. There you will find either the physical damage, or if you cut on the bark and look for where the green turns to brown, you may find where disease canker has entered in, cutting off the supply of nutrients to the apical (uppermost) parts of that twig or branch.
In addition to dieback, unhealthy or stressed trees often grow branches in a non-typical place or places. This is called “epicormic” or “adventitious growth” as mentioned above. Sometimes you will see advanced dieback or many of the branches dead in the canopy of the tree, whereas the bottom of the tree was sprouting numerous branches. Even though it looks like it is still growing, this is a sign that the tree is unhealthy or stressed.
Splitting and sloughing off of bark and the presence of fungal growth are often symptoms of dead, dying, or unhealthy trees. Even if part of th4 tree seems alive and healthy still, other parts of the tree with wood decay fungal growth can weaken the tree and eventually cause damage to it. In addition to fungi, insects are often attracted to dead or dying trees, bore holes in there and the larvae feed on the wood. These insect pests are NOT the primary cause of the damage, but are secondary and should not be considered pests, but a sign that the tree is decaying or dying. In the animal kingdom they would be the vultures, not the lions.
It’s important to note that even evergreen trees will lose leaves or needles during certain types of the year. Other trees may keep brown, dead leaves on them, even over the winter, until the new green foliage emerges. Species like Southern Magnolias, hollies, and pines will have leaves yellow and drop, but this is natural.
If you think that you have a tree that’s unhealthy, stressed, or dying, you can always reach out to your local N.C. Cooperative Extension office, where the agents there are more than willing to help you identify the issues with your tree. There are also services like the NC State University Plant Disease and Insect Clinic where they help you identify from photos or from physical samples what may be going on with your tree. Finally, you can hire professionals like arborists or landscape companies that may be able to come out to your home, take a look at the trees and tell you what’s going on.