Alan, this is based on a very old study from the early 1900’s. There was a thread about it that you may have missed:
White paint is the way to go but I wasn’t sure if it would clean up out of my sprayer so I decided to just use Surround with a massive sticker. Whitewash also could be a good option but I didn’t have the kind of lime needed handy. I was also too late in the season to do it and the Surround will stay on long enough. If we get another early spring next year I will be painting all my apricots and Jap. plums white in February, either with whitewash or dilute paint I expect.