Disease prone?

Chitalpa tashkentensis

Has anyone got any info about this cross between Catalpa bignonioides (Southern catalpa), not the most desirable shade tree, and Chilopsis linearis, (Desert willow)? It isn't strictly a native, but people are using it since it is a "son of" and supposedly resistant to mildew.

I decided to grow one in my garden, and it did wind up getting mildew late last year - I think, though, it was because I had just planted a number of new one-gallon and 4 inch potted plants around it and there may have been extra moisture in the air.

Somewhere on the listserv I thought someone had said there were disease problems?

Any info, ideas or help?