Different Types of Tree Bark Diseases

There’s no doubt that gardening is one of the most rewarding experiences.

After all, there isn’t a soul who wouldn’t rejoice at the healthy growth of their plants. At the same time, it’s also important to be wary of the potential threats. Especially in the case of bigger trees, you would want to keep an eye on bark diseases.

So, in the following sections, we have listed some of the most common tree bark diseases and how to spot them.

Types Of Tree Bark Diseases

To start off on a positive note, we would say that just because your tree has a bark disease doesn’t mean it’s beyond saving. But even before you can think about treating it, you have to know about the different types of tree bark diseases, and that’s what you will find below.

Canker Disease

One of the most frequently occurring tree bark diseases is the canker disease. It’s usually caused by a fungal or bacterial pathogen entering the tree to block its vascular system. This, in turn, prevents the intake of water and necessary ingredients, thereby causing the branches to die.

Naturally, trees that are already stressed or damaged are more susceptible to this disease. Fungus or bacteria enter the trees through wounds from environmental stress or injury. You can prevent this disease by ensuring suitable and healthy growing conditions with all the required nutrients and moisture for the trees.

Canker disease can further be divided into:

Thousand Canker Disease

Thousand canker disease actually includes various other tree bark diseases (hence the name). It can be identified by numerous small cankers or blister-like growth on the tree bark. Additionally, you may notice a surrounding amber stain or cracked bark in some cases.

It’s generally caused by bark beetles, which damage the bark from underneath, allowing the fungus to enter. Moreover, a tree may have been infected for a long time before showing the above-mentioned signs.

Cytospora Canker Disease

Browning needles and dying branches in species like pine, spruce, poplar and willow trees may be due to the cytospora canker disease. Caused by a type of fungi, it predominantly attacks stressed trees, especially with root, drought, frost, or sunscald-related damages.

That said, different trees may exhibit different symptoms. For instance, some trees may rapidly change the bark color. If you remove the thin outer layer, it’s highly likely that the inner bark will develop a dark color.

Other symptoms include cracks near the cankers, resin-like patches, or small black bumps. Adequate watering is a good way to prevent this disease.

Bleeding Canker Disease

The bleeding canker disease mainly attacks maple trees, making the bark appear wet with a reddish ooze and dead wood underneath. It can also be identified by the bark coming away from the lower part of the tree trunk.

Dutch Elm Disease

The Dutch elm disease is essentially an invasive fungal infection that affects the American elm and other elm species. It’s caused by either the native or European elm bark beetles.

These beetles are covered in fungal spores and dig deep into the branches, eating through the healthy tree sap. They spread to the sap-conducting tissues and clog the vascular system, making it difficult for the crown part to receive water.

Besides causing wilting, it damages individual branches by causing the yellowing and curling of leaves, which is the first sign of the disease. All the leaves will eventually turn brown and fall off. Although pesticides are the most effective way to curb the disease, its fast progress can become irreversible if left unchecked for long.

Beech Bark Disease

The Beech Bark disease is a relatively new discovery for beech trees caused by a combination of the native nectria fungus and European beech scale insect. It begins with the latter borrowing into the bark for “finding food”. Once inside, the nectria fungus affects the interior of the tree.

As a result, cankers and oozing blisters cover the whole branch, while the foliage becomes sparse and yellow. However, if you don’t spot any such significant signs, there’s a good chance that the tree has weakened, thereby becoming more susceptible to other diseases.

There are multiple chemical treatments available to stop the spread of this disease from one tree to another.

Black Knot

Perhaps the black knot disease produces the most ugly-looking growths on fruit tree branches, but that’s not the only problem. This fungal infection (from the fungus Apiosporina morbosa) causes tarry, black swellings on the branches that ultimately kill the tree limbs.

They initially appear as greenish or greenish-brown spots on fruit trees like cherry, plum, apricot, etc., and may take up to 3 years to turn black and release the spores. Hence, it’s very easy to confuse them for harmless mold formation.

One of the most effective ways to combat it is by pruning the trees during late fall, winter, or early spring when they are dormant. Moreover, the blades must be properly disinfected to prevent the transmission of the fungi.

Black Rot

The black rot disease affects hardwood fruit tree branches, especially apples and plum trees. Similar to some other diseases, the fungus (Botryosphaeria obtusa) enters the branch through wounds caused by insects, improper pruning, or environmental damage. The bark usually appears reddish-brown at the start before turning black. It may also shrink and peel if left untreated.

Pruning to remove the infected branches will help you negate the risk, but make sure to dispose of the clippings as the fungus can survive on dead tissues.

Final Words

We hope that by the end of this post, you have gained sufficient knowledge on the prominent telling signs of the most common bark diseases. We would still recommend getting professional help if you’re a first-time gardener or have just ventured into large-scale gardening.