Yellowing between the vein is a symptom of iron deficiency which is usually caused by very high soil Ph. Some plants can take high Ph and some don't. Research Iron chlorosis on the web.

The nibbles by some insects are probably what you see with the notches in the leaves. Normal for this time of year and unless it gets to look like a real infestation, I don't think you have anything to worry about with that.

Thank you! After Googling my husband was positive we had verticillium wilt but the pictures didn't look quite right. When I google iron chlorosis it looks exactly like what we have. I'm glad I asked!

If you had verticillium wilt, you would know it!! There is no mistaking the very rapid effect of that pathogen.

Red maples (Acer rubrum), which is what you have, are very tolerant of a wide range of soil pH, more so than any other maple species. Your soils must be quite alkaline to result in that degree of chlorosis. You can address with a chelated iron product but that is only a temporary fix. Adjusting a high pH soil is a difficult thing to accomplish.

One other possibility...have you had exceptionally excessive rainfall this year? Highly saturated soil that persists can cause root die-back. The effects can show up as leaf chlorosis as well. Just a thought...