Please see the photos below. These leaf depictions are a result of Anthracnose Fungus which manifests itself in a few different ways.
These are Maple leaves. This situation may or may not be evident just yet but a lot of trees will display similar damage over the coming month. Maple, Oak and a few other tree varieties can get Anthracnose. The wetter the Spring, the more issues there will be with all varieties of fungus and we all know just how wet this Spring has been in the Chicago suburbs.
Anthracnose is an airborne spore which blows onto susceptible trees and even some shrubs. We do ‘not’ recommend treating for this particular fungus because it is ‘not’ a yearly occurrence like it is with Apple Scab Fungus on Crabs or more recently, Rhizosphaera Needle Cast Fungus on Spruce trees. The extent to which Anthracnose Fungus will affect trees is an unknown in any given year. We must be ‘proactive’ in treating for any fungus and once a fungal condition begins to show visible signs, it is already too late to treat for that season. Why spend money on a treatment that is only an issue on occasion?
This next photo shows seemingly healthy green Ash leaves strewn about on a brick patio.This situation is also a result of Anthracnose Fungus. In the case of Ash trees, Anthracnose attacks leaf stems causing them to weaken and disconnect from the branch. As a result, individual leaves or clusters of leaves fall to the ground. Other than being unsightly, this condition should stop occurring after a few weeks. In a bad year, an Ash can lose up to 75% of its leaves but the tree will re-foliate as the Summer progresses. Your tree will not die due to this condition.