Hypoxylon Canker

Hypoxylon Canker

Hypoxylon Canker is an extremely destructive fungal disease that targets trees that are already weakened.

What is Hypoxylon Canker?

Hypoxylon canker is a fungal disease that affects trees, particularly hardwood trees such as oak, maple, and ash. It is caused by the fungus Hypoxylon mammatum, which is found in most temperate regions of the world.

The fungus infects the tree through wounds or natural openings, such as leaf scars or lenticels. It then grows within the tree’s tissues, causing the tree to produce abnormal amounts of lignin, a chemical compound that gives wood its strength and rigidity. This overproduction of lignin causes the tree’s tissues to become thick and woody, leading to the formation of cankers on the tree’s branches and trunk.

Cankers are small, sunken areas on the tree’s bark that are often surrounded by a ridge of swollen tissue. They are usually dark in color and may be surrounded by yellow or brown discoloration. The fungus may also produce fruiting bodies, which are small, black, spore-producing structures that can be seen on the surface of the canker.

Common Hypoxylon Canker Symptoms

The symptoms of hypoxylon canker vary depending on the tree species and the stage of the disease. In the early stages, the tree may exhibit yellow or brown leaves, premature leaf drop, or thinning of the canopy. As the disease progresses, the tree may develop dead branches or a thinning canopy. In severe cases, the tree may die.

  • Dark spots on tree bark.
  • Yellow or brown leaves.
  • Premature leaf drop.
  • Thinning of the canopy.
  • Dead branches.

How Does It Spread?

One of the most common ways that hypoxylon canker spreads is through the movement of infected wood or debris. For example, if an infected tree is cut down and the wood is used to make firewood or wood chips, the fungus can spread to other trees through contact with these materials.

Prevention and Treatment

To prevent the spread of hypoxylon canker, it is important to practice proper tree care and maintenance. This includes avoiding wounding trees unnecessarily, such as by pruning branches too close to the trunk or driving nails into the tree. It is also important to properly sterilize pruning tools between uses to prevent the spread of the fungus from one tree to another.

If a tree is infected with hypoxylon canker, it may be possible to slow the spread of the disease through the use of fungicides. However, treatment is often expensive and may not be effective if the tree is already heavily infected. In such cases, the best course of action may be to remove the infected tree to prevent the spread of the disease to other trees.


In conclusion, hypoxylon canker is a serious fungal disease that can cause significant damage to trees. It is important to practice proper tree care and maintenance in order to prevent the spread of the disease, and if a tree is infected, it may be necessary to remove it in order to protect other trees. Looking for other Tree Diseases?

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