Chinese Pistache Tree: Identifying White Spots and Branch Dieback

A homeowner in Dallas is concerned about their 19-year-old Chinese pistache (Pistacia chinensis). About 18 months ago, they noticed small, smooth white spots on the branches. The tree appeared healthy and full at the time, so the issue was dismissed. However, in late spring to early summer of the current year, several small branches became lifeless, and the canopy has thinned by roughly 25 percent. The trunk looks sound, and the tree holds sentimental value for the family.

Expert Assessment

The tree's foliage appears green and healthy overall. The white spots are lichens—a symbiotic organism of fungi and algae—and are harmless to the tree. Lichens often colonize bark when canopy density decreases, allowing more light to reach the trunk and branches. They are a symptom of thinning, not the cause.

Recommended Action

Begin a fertilization program next spring to boost overall vigor. Apply a balanced 10-10-10 fertilizer at a rate of 1 pound per inch of trunk diameter. Scatter evenly around the drip line and water in thoroughly; applying just before rainfall eliminates the need for supplemental watering. Fertilize after leaf-out in spring. This will encourage denser foliage, which naturally shades out lichens over time. Beyond that, the tree looks structurally sound.