Hello Emily,

The red spots on the maple leaves are caused by Maple Bladder Gall. Read more here: https://extension.psu.edu/leaf-galls-on-maple#:~:text=Description,turn%20red%2C%20and%20eventually%20black

Bladder maple galls do not seriously affect the health of the tree. It is just a cosmetic issue.

However, the crown of your sunset maple is thinning out. It is difficult to determine the cause from the picture. It could be due to other insects or diseases or root problems such as girdling roots. Environmental problems may also cause it, such as herbicide application to the lawn.

A certified arborist will be able to properly assess your tree. To find one in your area, go to www.treesaregood.org the website of the International Society of Arboriculture.

Thank you for contacting Ask Extension.