April showers bring May flowers. We have had ample rain this spring and we can see the difference it has made in our plants and lawns. I have a climbing Hydrangea at my house that is attached to my privacy fence in the back yard. This is the first spring we have had blooms. It is wonderfully endowed with large white blossoms. Unfortunately all this rain can cause some issues. One of those issues is and increase in Anthracnose on Maple leaves.
Anthracnose is a fungal disease that infects the newly emerging foliage. Because it is a fungal disease, it is more prevalent during periods of moderate to heavy rain. The lesions that form on the leaves are large dark brown irregularly shaped areas of necrosis (death) that can be mistaken for tar spot. This fungus can also attack twigs and cause cankers that results in dieback.
Control of this pathogen is usually unwarranted. The lesions are usually only an aesthetic issue. One cultural practice that will reduce the amount of spores traveling around, is to pick up and dispose of any leaves that have fallen to the ground.
Tar spot is another fungal disease that effects Maples. It too is merely an aesthetic issue and does not require fungicide applications unless you really don’t like the way it looks.