What are the possible treatments for a diseased tree?

Do you know how to tell what state of health your trees are in? There are various signs that allow you to determine if one of your trees has some sort of disease: dead or split branches, decaying branches, trunks or roots, white or black spots on the leaves, an insect infestation, fungus, abnormal tilting, etc.

The most common tree diseases in Quebec have diverse origins, so each one requires a specific kind of treatment. That’s why it’s important to properly identify the disease in question in order to determine what type of treatment should be applied to your sick tree.

Treating a sick tree: the most common diseases

Powdery mildew

This is a fungal disease that attacks the outer layer of the leaves, covering them with white spots that have a velvety appearance. The fungus appears in the summer and remains on the leaves until they fall off in the autumn. This disease only affects the growth of the tree. So the best treatment is to thin the tree to ensure that the branches have adequate aeration and, most importantly, to avoid watering it in the evening.

Beech bark disease

This is an exotic disease caused by a tiny insect (a cochineal) that takes malicious pleasure in boring holes in the bark of the tree. These holes consequently allow pathogenic fungi to take hold. You’ll notice blisters, as well as a sort of white waxy substance, on the bark. A more severe infestation will result in the discharge of a dark reddish-brown fluid.

If you believe that one of your trees is suffering from this disease, the best way to treat it is to spray or brush the bark with dormant oil.

Dutch elm disease

Unfortunately, this incurable disease has taken many victims, especially in Eastern Canada. During the summer, the leaves wilt, turn brown and then roll up on themselves before falling to the ground. The tree will die soon thereafter and will quickly contaminate the neighboring trees. To prevent the disease from propagating, the felled tree and any cut branches must be disposed off completely. Preventive treatments consist of pruning the trees and applying pesticides.

White pine blister rust

Of fungal origin, this disease can be recognized by the appearance of orangish patches that form on the trunk. Very widespread in Canada, white pine blister rust is also characterized by strangulation of the trunk, accompanied by the discharge of resin. The recommended treatment consists of removing the bark in and around the affected area.

Arborvitae leafminer

Commonly called “cedars” in Canada, arborvitae trees or thujas are coniferous trees that are commonly attacked by caterpillars. These pests damage the tips of new shoots, turning them yellow and subsequently causing them to wither. The preferred treatment is to cut off the new growth and then spray the tree with dormant oil.

Emerald ash borer

An insect originating in Asia, the emerald ash borer, appeared in Canada during the decade of 2000 and has since decimated millions of ash trees throughout the country. The insect destroys foliage and bark, and the larvae penetrate the living part of the tree, eventually killing it. If the leaves of your ash tree turn yellow or if there are serpentine tunnels visible underneath the bark, it’s very likely that the tree has been attacked. An arborist can advise you as to whether it’s possible to save the tree using a TreeAzin treatment or if the only recourse is to cut it down to prevent it from contaminating other trees.

Rely on the experience of a professional tree trimmer

To learn more about the treatments that should be administered to diseased trees, please don’t hesitate to contact the expert arborists at Émondage SBP. Day after day, our expertise, our extensive knowledge of trees and our state-of-the-art equipment all contribute to preserving your plant heritage!