Hello, need help identifying what is killing my ornamental pear, and whether there is any treatment that will work. Here are pics of the leaves. This has happened several times, in fact, it is now basically continuous. I treat it with a systemic. It works for a month, then the disease returns. I've sprayed the tree all over, and done the soil drenching, and it still returns. Thanks in advance for your assistance. When I read about Anthracnose, it doesn't really sound exactly like the problem we are having, but I can't figure out what it is.

Image link: