Shiro and Methley Plum Trees losing leaves
Hi Everyone. I thought I'd posted a message on May 5th, but cannot find it. So I'm trying again. I have 2 Methley and 1 Shiro Plum trees that are 4 years old. One of the Methley's is doing okay, but the other and the Shiro (that are next to each other) are suffering from.....? They blossomed out but then began losing leaves like crazy, maybe half. The leaves first dried out real bad then fell. I checked for insects, but couldn't find any. Some of the leaves had holes. The bark on the trunk of the Shiro is split and last year it oozed. Local coop ext. said this isn't a problem. I painted the trunk with latex. I have babied these trees, including mulch, compost, dormant spraying for insects, fungus, etc., and dormant oil spraying. I'd hate to lose them! Could this be a bacterial canker? Shothole? A virus? What's the treatment, and how does one know for sure? I showed photos to two coop extension folks and 3 master gardeners, and they all had different opinions. Yikes! I welcome any feedback. Thanks!