SALEM — After autumn's end comes the problem of what to do with all those fallen leaves. Far too often, homeowners rake the leaves into big piles surrounding the trunks of their street and yard trees. Some of these piles resemble leaf volcanoes. Unfortunately for trees, those piles can be just as destructive as a volcano, according to Oregon Department of Forestry Community Assistance Forester Katie Lompa.
"Leaf volcanoes trap moisture against a tree's trunk, allowing fungi to flourish," said Lompa. "Peel back wet leaves that have been left against a tree trunk and you may see tell-tale white patches revealing the initial stages of rot."
The solution? "Leave a ring at least three or four inches from the trunk free of leaves," said Lompa.
Leaves are great for mulching around plants but first consider shredding or composting them, Lompa added. A thick layer of whole leaves can become compacted and create a barrier to air and water reaching the soil and plant roots. Mulching with organic material that is already broke down into smaller particles allows for more air and water movement, which helps reduce the risk of rot and other fungal diseases.
"Because leaves can drift in winter winds, some homeowners may choose to bag up their leaves. Before doing so, consider contacting your city or homeowners' association. Many Oregon communities have an urban forestry program that might include community yard debris composting. Even if you won't be using your leaves, someone else can."
Finally, certain diseases can overwinter on fallen leaves, Lompa noted. "So if you noticed powdery mildew or leaf spotting during the summer or fall on your deciduous trees, consider disposing of the old leaves to reduce the risk of infecting new leaves in the spring."