In my experience, and it would seem our climate is fairly similar, Chinese Elms seem to do better for me if their soil is a little dry in our crappy "spring". Damp soil and chilly nights seem to cause these flair-ups. And there has been plenty of those...like for two and half months!
I've killed about 6-7 and my buddy killed his a couple years ago with a badly timed re-pot. I always seem to get useless "sub-tropical" varieties...they can't handle the massive temp swings we get in the northeast these days....
As mentioned, might be holding some water in the soil....
Still got one Elm though!