Ok, I live in Brazil, but I have noticed this in Hawaii as well as in pictures of India and the Philippines.
WHY DO THEY PAINT TREE TRUNKS WHITE?
Some answers I have gotten here are
Keeps ants out of the trees… White paint? HOW…
Keeps cars from crashing into them…It does not (sheesh)no better then no paint any way.
And if that’s why, how come the trees planted in high-rise apartment penthouses are also painted white.
It keeps rats out of the trees, again how… also, I understand there are no rats in Hawaii
Because the imported mongoose population did away with them.
It looks nice…Ok so folks who live in tropical countries have no taste, still there are
A few nature buffs I know who have painted trees in their front yards that would
Presumably prefer the natural look.
Re: #1 - It is possible there is some sort of insecticide mixed in with the paint. However, the paint likely clogs up insect holes and holes created by woodpeckers, nuthatches and other insectivores that drill into the tree trunk.
I do know, however, that the birds would hang around the white part of the tree more, since it was easier to spot insects crawling on the white-colored rather than the normal-colored sections, taking away some of the insects natural camoflage.
Re: #2 - Don’t know about the trees in the high-rises, but we had some of our trees trunks painted white to keep the cars from crashing into them. Many of the trees are close to the road; and our parking lot is in the midst of a forest, so people are parked between trees.
It is true that ants don’t like to cross a white line. I read about it somewhere else and it has been mentioned here before, and I for one have tested it. Of course, being the inconsiderate butthead that I am, I found a typical test subject on a sidewalk one fine day, and drew a 6-inch dia. chalk circle all the way around it. The ant did walk around the inside of the circle a few times (this took ~15 minutes), before carefully picking its way across a narrow part of the line.
As to the other reasons, If you paint trees white, I guess you can see 'em better at night, if you had to.
The rat thing I don’t know about. Around here, suburbanites call rats “nature”, except when one falls into the swimming pool. Farmers call rats “targets”.
It looks nice? I never seen anyone else paint their trees any other color. - MC
“Winter injury [to cherry trees] is indicated by long cracks in the bark, caused by sudden drops in temperature or very cold temperatures. These cracks serve as a source of infection, which can be prevented by painting the cracks with wound paint or by painting the trunks of young trees with white latex paint.”
“Tree wrap provides important protection against winter sunscald and is especially important for fruit trees and others with smooth bark. Put the papery wrap on just like a bandage beginning at the bottom of the tree. Some people prefer to paint their trees with white latex paint which serves the same purpose.”
“Sunscald on trees can be prevented by wrapping the trunks with a commercially available tree wrap or with burlap or agricultural fleece. You can also guard against sunscald by painting the bark of young trees with white interior latex paint mixed with water 1:1, in the fall. The light color reflects the sun’s rays and prevents sudden temperature changes.”
Protection against insects and sunscald seem to be the most common reasons for painting trees white, but references to links which are no longer available indicate two other reasons – to mark hiking trails, and to create a more formal, uniform appearance (as in a city park).
I can’t tell you about the countries you mentioned but in the USA, especially in the south, this was a fashion for a while. Seldom seen now, it used to be common to see white tree trunks in yards of the south. This was often accompanied by old car tires painted white and used for flower bed borders or to ring the bottom of the tree. People who went in for this style were also prone to add “yard art” in the form of statues of deer or a terra cotta squirrel clinging to the chimney. This has been called “white trash” landscaping. But that is not really true. Real white trash folks just have a few old Chevys up on blocks in the front yard.