Why they paint tree trunks white

Dear Matthew Alice: Why are the bases of some trees (mostly palm trees) painted white? — Michelle S., Chula Vista

This mysterious arboreal graffiti actually has a practical purpose. In hot climates, white latex exterior house paint or whitewash is applied to protect tree bark from sun damage or stress, since it reflects the sun’s rays. In cold climates, it’s used mostly on fruit-tree trunks to keep winter sun from warming the dormant plants and sending them into early bloom and potential frost damage.