Leaf dropping elm

[Damondog11]

Hi,

We have a large established Chinese Elm (I would guess about 50 ft.) in our front yard. For the past 3 years, it has been continuously dropping its leaves from the time the leaves develop in the spring all and continues doing it through out the summer and fall. It keeps growing new leaves all season, so it is still provides a good source of shade.

We have lived in this house for 20+ years and it has never done this before. We have it professionally treated for the elm leaf beetle every year so I am convinced it isn't' that. I don't see any bugs, but the leaves do get spotted.

Any ideas what this is and how to treat it?

Thanks....