A common question I've had from many property owners this past summer relates to mushrooms growing on trees. Why are we seeing excessive growth of mushrooms on trees now?
Mushrooms are referred to as the fruiting bodies of fungi, and they typically occur on the bark and branches of trees that are under stress, or in many instances, on trees that are slowly dying. It is important to know tree mushrooms produce very small spores that are released into the air -- usually by the wind -- to produce new generations of fungi. The mushroom itself is produced by a network of very fine, threadlike, structures that are collectively called mycelium. These fine threads work their way through the decomposing portions of trees, especially on bark and wood, and other organic matter associated with trees.
The mycelium threads act like rootlets to absorb decomposed nutrient material from the decaying wood. However, mushrooms are even far more complex than I have described simply previously. When you see those growths -- often white or brown or grey in colour -- on your tree, the mushrooms are consuming that portion of your tree. But remember, they are not edible. They are working to reduce a tree back to the soil to start the natural cycle of life.
Apple trees have had a great deal of this fungal growth this past year. Air humidity has often been higher during this past summer than in previous summers. Higher humidity tends to favour the development of the fungi. I have included some sample images of these fungal growths. Mind you, the fungi do not grow on healthy twigs, branches and trunk bark. They grow on woody matter that is dying or dead.
In a large number of yards I visit, the homeowner has asked about these mushrooms, wondering if the mushrooms are they killing the tree. As previously stated, the mushrooms are there because parts of the trees are either dying or dead. The more mushroom growth that is present on the tree, the more the tree is telling the homeowner it is dying. I see this fungal growth on many apple trees, especially this year throughout southern Manitoba. Apple trees over the past few years have been infected with diseases such as fire blight and black rot. These are deadly diseases that are either very difficult to control, or simply impossible to control.
Annual infections of these diseases gradually stress and ultimately kill susceptible parts of the trees. People simply do not realize that their trees are slowly dying and simply do nothing. It is at the advanced stages of this disease I am usually called in to diagnose what is going on with the sick tree.
Decay fungi are nature's way of recycling a dead and dying tree into organic matter that is further broken up in the soil. You may not be very assured by the appearance of mushrooms, but they are simply a small part of the life-and-death cycles that serve important functions in the complexity of life on Earth.
viburnumtrees@shaw.ca
