Lichen on Mulberry Tree: Symptom of Underlying Stress

Lichen on Mulberry Tree: Symptom of Underlying Stress

A 3–4-year-old fruitless mulberry has white spots on the trunk and slow growth (2–3 ft in 3 years vs. 30 ft for an older tree).

White spots on trunk

Close-up of lichen

The Spots Are Lichens

Lichens are harmless epiphytes—a fungus + alga partnership. They photosynthesize their own food.

Why They're There

• The tree has a thin canopy, allowing light to reach the bark.
• Lichens indicate reduced vigor, not cause it.
• The older tree's dense canopy shades the trunk, suppressing lichens.

How to Improve Growth and Suppress Lichens

1. Fertilize: 10-10-10 at 1 lb per inch of trunk diameter, spread to drip line, water in. Best applied just before rain.
2. Water deeply during dry spells (1 inch per week).
3. Avoid "weed and feed" lawn products near the tree—they contain herbicides that harm broadleaf trees.
4. Mulch properly (2–3 inches, not touching trunk) to conserve moisture and reduce grass competition.

Outlook

With improved vigor, the canopy will densify, shade the trunk, and lichens will naturally decline. The tree is not dying—it's just underperforming due to resource limitation.