Dormex is a very powerful PGR, and I would suspect has much more to do with any growth issues than a chloride problem. We have used Dormex on cherries for 20+ years, but the few times we tried it on plums it was a disaster. I can see that sections with over spray actually look a little nicer some years, so I would suggest applying a very light rate, if only in a section or a couple rows, and see if that helps. I would also suggest trying an earlier application day as a trial, since in our experience the bloom date for the treated area would be so much earlier is wouldn’t help with pollination. If you can have an overlapping bloom even with a Dormex application on one variety I would imagine you might be applying it to late, which would also kill a number of flowers before they bloom and leave you with a tree much like you described.