Watch Your Conifers for Signs of Annosus Root Rot

3 February 2017
 Categories: , Blog


Coniferous trees are known for being pretty low-maintenance. You don't have to sweep up fallen leaves as you do with deciduous trees, and once they're a few years old, you don't typically have to prune them. However, there is one big threat to coniferous trees that you'll need to watch out for, whether you have longleaf pines, blue spruces, or any other species. Annosus root rot, a deadly disease, can attack conifers at any time.

What is annosus root rot?

Like most diseases that affect trees, annosus root rot is caused by a fungus. The species of fungus is called ARR, or Heterobasidion annosum. It is passed from tree to tree through connections in the root systems. If one tree has annosus root rot and its roots grow towards your tree, the fungus can be passed from the roots of the infected tree to those of the healthy tree.

What are the signs of annosus root rot?

Ultimately, a tree with annosus root rot will die. However, if you pay close attention to your conifers, you'll see signs of the disease long before this happens. Symptoms include:

  • Holes or cankers in the wood near the bottom of the trunk

  • The appearance of white, stringy wood near the bottom of the trunk and on any large roots that happen to be exposed

  • Resin-soaked, sappy patches near the roots

  • Certain branches seeming to die off with the appearance of brown, crumbly leaves

What should you do if you think your tree may have annosus root rot?

If you do notice signs of this disease, don't ignore it. Even though the tree will likely die within two or three years, it's best to call a tree service company and have the tree felled before that point. The sooner the tree is removed, the lower the risk of the disease spreading to other nearby conifers. Make sure the tree removal company disposes of the infected wood responsibly. It should be burned to kill any lingering fungi.

Can you protect your tree from this condition?

There's nothing you can do to 100% guarantee that your conifer won't come down with this condition. However, you can decrease the risk by keeping your tree in good health so it's better able to fight off the fungi when exposed. In periods of drought, water the tree. If you notice debris building up near its trunk, rake it away so moisture does not get trapped against the trunk.