by Nancy Penrose

Root rot is a serious tree disease caused by fungi. It is usually found in mature trees or younger trees that have damaged roots.

Root rot can stunt the height and diameter of a tree. It can also cause dieback (the tree begins to die from the tip of its leaves or roots backwards), leaf discoloration and leaf loss. Indicators of root rot include yellow crown, a red-brown stain on the tree?s core and thinning leaves. When a tree has root rot, its overall health will begin to deteriorate. Eventually the tree will die.

There are many different types of root rot. In the Pacific Northwest, laminated, annosus and armillaria root rot are especially common.

Laminated root rot, also called yellow ring rot, is the most serious type of rot. It can infect fir, hemlock, larch, spruce and western red cedar trees. Most pines can tolerate or resist infection.

Healthy trees acquire laminated root rot by coming into contact with an infected tree. The rot destroys the tree?s roots, which can cause it to topple over during windy weather. The damaged roots can also make it difficult for the tree to absorb water and nutrients. Older trees can live with laminated root rot for many years, while younger trees will succumb quickly to the disease.

Annosus rot is a fungus disease that can reduce tree growth. It can also kill a tree. The rot can affect some pine tree species, as well as hemlocks and firs. The infection starts off as a red-brown stain inside the butts and roots. When the disease gets worse, brown lines will streak across the wood, and white lines will show up on the inner bark.

Armillaria root rot is another type of fungal infection. A tree with armillaria root rot will usually have mushrooms at its base. The fungi enters the tree through a wound and then grows into the roots. Trees can have the rot for up to six years without showing any signs of infection.

Give us a call if you are planning on purchasing a big tree for your landscape. We can give you tree care tips and show you how to prevent root rot and many other types of diseases that can affect trees.

Nancy Penrose is owner of Big Trees Inc. (, (tree nursery Snohomish, WA), one of the largest Seattle tree nurserys (see Big Trees planting services page at, specializing in large trees for sale and transplant tree service. For more tips on tree installation or care go to See our video at and connect with us on Facebook at

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