Armillaria Root Rot: A Deadly Tree Disease To Watch Out For

Trees are prone to a number of fungal infections, but few are as serious as armillaria root rot. This condition, which can affect most any species of tree, causes the tree's tissue to essentially rot from the inside out, beginning in the roots. If you have trees on your property, it is important to be aware of the signs of this disease so you can act appropriately if it does appear.

What are the signs of armillaria root rot?

In its earliest stages, trees with this condition show no obvious signs of symptoms since the fungi are still deep within their roots. By the time the tree starts showing symptoms, it has been infected for quite a while. These symptoms include:

  • The appearance of "mushrooms" at or near the base of the tree
  • A string-like appearance of the wood in the lower stem once the bark has been peeled away
  • Dieback of foliage; the leaves typically turn yellow and then fall away
  • In coniferous trees, the production of an extraordinarily large number of cones
  • The secretion of a large amount of resin from the lower trunk of the tree

Symptoms vary somewhat between tree species, so a tree infection with armillaria root rot may show any or all of the symptoms listed above.

How is the disease spread?

Armillaria root rot is spread from tree to tree through the roots. When an uninfected tree's roots come into contact with roots that do harbor the fungus, fungal spores are passed on to the previously uninfected tree. They work their way into the interior of the roots and begin to replicate, eventually causing a full-blown infection.

What should you do if you suspect your tree has armillaria root rot?

The first thing you should do is call a tree care expert. Several other tree diseases, including thousand cankers disease and black canker, can mimic armillaria root rot, and a tree care expert can confirm your diagnosis to ensure you approach the situation properly.

The tree will die from this disease, so there are no treatment options. However, it is often recommended that you have the tree removed from your property rather than leaving it to die (and potentially fall, causing damage) on its own. A tree service, like Desert Gardens Outdoor Services, Inc., will also likely want to fumigate the stump of the removed tree in order to kill any fungi that are left behind and reduce the chances of spreading root rot to other trees in the area.