This seems to be a debatable topic with no perfect answer. I have been planting fruit trees for 5+ years and that is the extent of my personal experience. I live in the low desert and it gets very hot here for sure. Until a couple weeks ago I had never painted any of my trees.
However at the end of last summer I noticed several of my older trees had sun damage. Sure no big deal right? I mean the tree will live and still produce fruit. However the damaged areas are where pests attack and my choice not to paint them has made several of my trees more vulnerable to infestation. So I went down to the local Home Depot and purchased a brush and some Tree White and asked my son to paint my trees.

Any interior flat latex paint diluted 50% with water will work and is cheaper than Tree White.

The link below is from an authoritative SoCal source so check out the video.

Here is a link that might be useful: How to Paint Your Trees

I read somewhere, the Fedco catalog, I think, that if you mixed joint compound with white latex paint and put it on the lower trunks of apricot and peach trees, among others, it would help against borers. I mixed some up, and then since I had plenty leftover, I decided to paint all my 1-4 year old fruit trees (apples, pears, cherries, sweet cherries, plums, apricots) as high as I could reach. Now I am wondering if that might have been a bad idea, since I keep reading how one should dilute the latex paint. I applied this thin paste about 1/16 to 1/8 inch thick. Will the spring rains wash it off or soften it enough that it will expand or crack with the tree growth? Will it suffocate the tree? Should I do something about it? What do you think? northwoodswis