I am sorry to be the bearer of bad news, but if you go to Howard's books and look up Bradford Pear, which I suspect your trees are, you will see that this is a tree that has problems in the North Texas area. They are short lived and are suseptible to soil born diseases.
I would suggest you replace them. I think Howard would give the same advice. I know it is hard to get rid of a tree that you have enjoyed for some time, but a better adapted tree is worth the trouble.
_________________ Tom and Diane Hodnett
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