Root rotting fungi making an appearance at a site near you.

Be on the lookout for mushrooms at the base of your trees.  After months of drought followed by the recent heavy rains, the conditions are ripe for the development of mushrooms near the base of woody plants. These mushrooms, known as fruiting bodies, are signs that your trees may already be infected by root rotting fungi.  The most dangerous of these is the Armillaria species.  Armillaria fungi are particularly lethal to hardwood deciduous trees such as oak, elm and honey locust.  These fungi create a hazardous problem for homeowners that have large mature trees near their home.

The fruiting bodies of these fungi are commonly called honey mushrooms because of their golden yellow color, but there is nothing sweet about them.  As Armillaria invade the wood of trees to extract nutrients for their survival, it degrades the structural integrity of the tree.  This often happens without any visible signs of infestation until mushrooms develop.  By then, the risk of tree failure is a reality.  There is very little that can be done for the infected tree.  Removal is usually the best option.  If the tree is allowed to remain, there is some chance that it could topple over onto a target such as your home, your car, or worse.  Contact a professional arborist immediately if you spot mushrooms at the base of your tree. 

Tree removal in this situation is not a job for the do-it-yourselfer.  Once a tree has lost its structural integrity its direction of fall, even in a controlled environment, becomes unpredictable.  Certified arborists receive special training to help mitigate the irregular behavior of trees with internal decay.  The most important reason to contact a certified arborist is to identify the pathogen and determine the best control measures to be taken. 

The loss of one tree by Armillaria could spell the beginning of disaster for your other trees.  Very often, the spread of a plant pest is checked once it destroys its host but Armillaria thrives on both living and dead wood and can remain active in your lawn long enough to attack healthy trees.  If removal is warranted, it should involve as much of the root system as is practical.  Of course you don’t need to rip out your entire lawn but you will want to remove as much of the infection as you can.

One of the very best ways to ensure a healthy tree is to keep it properly watered during drought so it can defend against invading pathogens.  By collecting rainwater, you may be able to capture enough supplemental water to keep your all of your plants healthy even during drought.