Four Signs of Sickness in Trees

//Four Signs of Sickness in Trees

Trees are vulnerable to a variety of different pests, pathogens, and parasites, which can lead to serious illness and, in some cases, premature death. And while there are a few threats that fail to cause many obvious signs, most things that attack trees provide a few clues that are easy for homeowners and property managers to spot.

Be sure to inspect your trees regularly, and reach out for help if you notice any of the following signs or symptoms.

Crown Dieback

Crown dieback – the progressive death of the leaves, shoots, and branches in a tree’s crown – is one of the classic symptoms of illness or maladaptation in trees. Dieback can be diffuse, and occur throughout various portions of the tree’s canopy, or it can occur in a discrete section of the canopy, perhaps affecting only a single major branch.

Dieback is almost always indicative of a problem, and it will take the trained eye of an arborist to determine the cause. In some cases, the issue may be relatively minor, such as an insect infestation that is limited to a single branch, but at other times it may indicate the presence of a serious, systemic illness. In either case, prompt action is imperative if you are to have any chance of saving the tree.  

Premature Leaf Drop

In an effort to save water, many hardwoods (and a few conifers) shed their leaves as the weather turns chilly. However, sick or struggling trees may release their leaves while the weather is still warm. Leaves produce the food for trees; so, when they are shed prematurely, the tree is robbed of some of the resources it needs to thrive. If the problem is corrected and supportive strategies implemented, most trees can recover from a bout with premature leaf drop, but it is not a symptom to ignore.

Note that some trees are considered “facultatively deciduous,” meaning that while they normally retain their leaves, they may shed them in response to environmental stresses, such as drought. While leaf drop in these trees may indicate the need for supplemental water, it does not necessarily imply that they have contracted an illness.

Poor Fruit Production

Many of the common pests and pathogens that afflict trees survive by stealing some of the tree’s resources. Fruit production is very energy intensive for trees, and those who lack sufficient resources and vigor are unlikely to produce a healthy crop. This can manifest in a number of different ways: The fruit can be undersized, misshapen or occur in smaller numbers than normal. In some cases, a crop may not be produced at all.

Of course, some trees simply have bad or strange years and produce poor crops without it being indicative of illness. However, it can be difficult for the layperson to distinguish between the two cases, so it is wise to have an arborist assess trees that produce poor crops, particularly if the tree has produced substandard crops in subsequent years.  

Damaged Leaves

A variety of different fungal, bacterial and viral infections damage the leaves of trees, as do a few insects and arachnids who feed on the tissues of trees. Some of these organisms cause the leaves to die from the margins, while others produce blotchy patches of dead tissue in the leaves. Still, others cause yellowing of the leaves or a series of dark spots to appear on the surface.

Insects and arachnids typically destroy leaves via their feeding behaviors – typically located on the margins of the leaves or the petiole (stalk). However, other insects may “skeletonize” a leaf, by munching on the tissue between the leaf veins.


Note that even healthy trees display these types of symptoms from time to time, so don’t panic if you see a tree in your front yard with a bit of dead foliage. Instead, you should simply contact your friends at Trav’s Tree Service. We’ll have one of our experienced arborists inspect the tree and determine whether it requires supportive measures or removal. Just be sure to act quickly, as trees that receive prompt treatment are more likely to survive than those who are allowed to languish for weeks or months before being treated.

By | 2017-09-25T15:58:39+00:00 October 10th, 2017|Tree Health|Comments Off on Four Signs of Sickness in Trees