Aside from esthetics, if you like the look of white trunks; it is only a method to protect sensitive trunks from sunburn, especially in young citrus and walnuts and cherries. If you decide to paint them, use a cheap white latex paint diluted 1 to 1 with water.

I agree with MrsG, not one orchard or yard in my area has painted the trees. I think that it looks ugly. I am not a commercial orchard so it does not matter but I would rather take my chances than to have White sticks in my otherwise pretty landscape.

Here in the desert it is certain death for exposed bark (and occasionally death for painted bark). Your sun may not be as intense.

Applenut

It all depends on what the weather is like where you live. If you get freezing nights followed by warm days in your area then damage can occur to the tree trunk on the southwest facing side of the trunk.

Where I live it is not uncommon for it to get down into the 30s at night and then reach the 70s during the day.

I decided not to paint my tree trunks last year. About 20% of my trunks split wide open on the southwest facing sides.

Six year old trees don't need painting young seedling get turned as transplanted like north side turned to southwest.
Paint does not need 50/50 with water color can be any you choose. 50/50 limit to make more paint volume.

I painted mine in hopes that peach tree borers would leave them alone.

Southwest injury aside

The paint does make it much easier to spot borer presence and act early.

OK gotcha, I now have seven possibilites! Wow! Thanks all. Mrs. G

I used to see even large established trees in countryside yards painted white up to maybe six feet. These yards were of simple homes or farmhouses where vehicles were often parked in the yard. I guessed then that perhaps it was to make the trees visible at night. This was in the era a single porch light and not the large yard security light now commonly seen. Yards were dark.

In our cold climate with late frosts, anything we can do to retard blossom development would be beneficial. Certainly protection against SW injury is important. Probably the labor intensive part of this idea is why more don't do it. Adding materials to the paint almost certainly would deter borers IMHO.

I don't mind the looks one bit. Have had none tree folks compliment me on their looks too. I'll venture a guess that orchard people aren't to willing to accept the expense of doing so on a large scale. Especially if not a major threat to them.

The main reason for white painting is of course being for hopefully some SWD protection. Maybe this isn't as big of a problem in your zone though? You may have noticed in a recent thread post of mine, that I continued higher up into some secondary branching as well. I had a problem going off the main trunk, so figured I just as well keep going, as am on a ladder at this point anyway.

Any delay in breaking dormancy by deflecting some heat of the sun will be a huge plus most likely as well. Especially the way that this Winter is going. Things will most likely be early regardless. Any late frost are bound to cause some misery.

As an added precaution, I paint it on at the base like some others here in the hopes of thwarting the borers. But I put it on extra thick in case this night give extra protection. Don't know for a fact this will help, but hopefully won't hurt anything either. So far so good.

I like the suggestions to put it thick on the base. I added diatomaceous earth to the mix, but will not dilute it this year. I painted after June borer egg laying so ended up getting pulling out 2 larvae on a wire per peach tree (Thanks Mrs G. and all).

Any other additive ideas out there to deter borers? Bits of fiberglass insulation? (Boy would that keep the heat off too!)

I paint the trunks white when the trees are young - use leftover paint - we have a lot of light blue. I wonder if I could use that instead of white? It would match our buildings! As far as appearance - I am more concerned about having healthy trees. Unhealthy trees don't look so good. After a few years the paint is less visible anyway.

Any light,(light enough to reflect the sun), color paint will do so use the light blue if you like it. Preventing the sunscald damage also helps keep the borers away-they like the weakened, damaged bark. You can add repellent if vermin are a problem in your yard. Just be sure to use interior, latex paint. Exterior paints could have (harmful)fungicides in them. Happy painting!

It's really up to you, I don't paint the trunks on my fruit-trees here in town and they do OK. The harsh sunlight is somewhat broken up with houses fence and trees.
The orchard out on my hobby farm is a different story, it's too open and the sun can beat down all day, I do paint them there, about every two or three years, I mix allot of water into the paint until it can be sprayed with a pump sprayer,...because I have allot of trees.

Thank you all, sincerely, Mrs. G

Another post mentioned adding joint compound to the paint to help with borers.
Dan

Wouldn't that wash off easy with rain?

No, the latex binders hold it all just fine. It gets mixed in about 50% to a thick slurry.

I have only seen this recommended for apple borers. I tried it for a few years but noticed no difference over straight latex paint myself.

I am not convinced either does much to deter them, but it sure makes it easy to spot their presence right away so you can dig them out. The ooze and frass shout out against the white.
some folks say if you time the painting to just after peak egglaying you can smother larva with a thick coat.