Four Things You Need To Know About Nectria Canker

Nectria canker, also called target canker, is a disease that can damage or even kill the trees on your property. Here are three things you need to know about nectria canker.

What trees are at risk?

Nectria canker affects hardwood trees like maple, honey locust, oak, walnut, birch and apple. It's an opportunistic fungi, so it tends to infect trees that are weakened due to various stressors. There are many things that can stress your trees and put them in a weakened state, including:

  • Drought or flooding;

  • Another fungal infection;

  • Improper pruning;

  • Cuts to the bark;

  • Root pruning;

  • Being transplanted;

  • Construction damage;

  • Deer browsing.

How does nectria canker spread?

Nectria canker is caused by Nectria cinnabarina, a type of fungus. This fungus is also known as coral spot. It lives in dead wood, and when spores become airborne, weakened trees in the area can become infected. Splashing water can also spread the spores from tree to tree, so infection can happen during any rainy part of the growing season in your region.

How is nectria canker identified?

If a tree is infected, you'll see orange-pink colored structures on the bark; these are the fungi's reproductive structures. If the fungi are able to get inside the tree, cankers—sunken lesions—will develop on the tree's bark. These lesions may be discolored. If these cankers are able to spread around the entire diameter of a section of the tree's trunk or limb, the tree may break in half at that weakened point. The tree can also die from the infection.

Can nectria canker be treated?

To treat your tree, the infected portions will need to be pruned. The diseased wood needs to be cut back to the healthy tissue. As you prune the tree, take precautions to avoid spreading the fungi to healthy parts of the infected tree. After each cut, dip your pruning shears in a bleach solution to disinfect them. This will slow you down, but it's an essential step. A tree trimming service can also handle this for you, if necessary.

Dispose of the pruned branches carefully to avoid spreading the fungi to healthy trees on your property. Ideally, these diseased branches should be burned, but if you're not able to do that, the next best thing is to place them in a plastic garbage bag and throw them in the garbage.

To protect your trees from nectria canker, reduce stressors that could weaken them. If your tree is stressed and you don't know why, consult with a tree service like Phoenix Tree Service.