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How Do You Know Your Tree is Rotting?

Varnish Fungus

It’s easy to miss tell-tale signs of serious decay in your large trees. Big trees can feel like permanent fixtures in the landscape that don’t need much attention or care. However, fungal decay can set in on large trees and before you know it you have a hazard situation on your property.

While inspecting a landscape recently, we came across a tree with an unusual looking red fungus growing at the base. This particular fungus is called “varnish fungus”, or Ganoderma lucidum. This fungus is a pathogen that lives in the soil, feeding on decaying matter. It enters into openings of the root systems of trees and shrubs such as oak, pecan, cedar elm, and pear trees, and large shrubs such as photinia.

Old landscape edging and hardscape damaged the base of this tree’s trunk, allowing for the fungal infection.

Varnish fungus is a slow growing fungus that can take years to completely kill a tree. It attacks the structural root systems; once infected and roots begin to die off, the tree becomes unstable and may fall during a storm or heavy winds. Often, when trees fall during a storm in North Texas, the roots are found to have been destroyed by varnish fungus.

Signs of Decay

Once infected, you might see a fruiting structure or a fungal conk, at the tree’s base. This is the most obvious sign of the disease. The fruiting structures vary in color, but tend to be a deep orange-red or rust color with shiny surface. Once the fruiting conk appears, it typically means the fungus has already damaged the tree’s roots.

Aside from the fruiting conk other symptoms your tree may be infected with varnish fungus might be difficult to assess, as they can mimic other issues. For example, infected trees can have large scale defoliation or large branches may die back.  However these symptoms could be related to other disease issues or physical damage. You’ll need to consult with an experienced and certified arborist for a proper diagnosis.

Prevention is Your Best Option

Because the varnish fungus pathogen enters into the tree by way of cuts in the roots, it’s important to protect the base of your trees. Never operate mowers and weedeaters against or near the base of your trees. Damage to bark at this level can create entry points for the fungus. Trees planted too deep or damaged by improper pruning practices can also be infected. If there is construction on your property be sure trees are properly protected. Always work with a qualified tree care company for diagnosis and care.

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