Hi,

This appears to be Anthracnose, which is a common disease that is occurring right now on many shade trees.

It is mostly seen on Oak, Maple, Sycamore and other shade trees. In most cases it isn't a major health concern to the tree and new growth will push out the older leaves - if they are still attached- as the season progresses. Usually the symptoms clear up with weather changes into the summer too. It will not transfer to the turf grass.

It helps trees to recover if you can lesson their stress symptoms. With the drought weather and going into the summer, if you can supplement watering when it doesn't rain, that should help as well. Water deeply so it can soak into the entire root zone of the tree.

To be proactive for next year, you can rake up and discard any fallen leaves which will help with the overwintering of the disease and also make sure to rake and dispose of leaves this fall as well.

You shouldn't need to use additional fertilizer and this could be excessive. The tree is capable of getting enough nutrients from the area soils anyways. If you use leaf litter (that is not infected with anthracnose) or mulch once a year to help keep soil moisture and add decomposing organic matter back into the root area, that is usually sufficient.

Let us know if you have further questions with this.

Emily