Lichens on Orange Trees: Cosmetic, Not Harmful

Green Blotches on Citrus Bark: Lichens, Not Disease

The greenish crusty growth on your orange trees is lichens—symbiotic algae+fungi. They're epiphytes (air-fed), not parasites.

Impact

• Slight negative effect only (shade reduction).
• Indicator of thin canopy (lichens need light).
• Not the cause of poor health.

Management

• Best control: Fertilize for dense canopy (10-10-10 at 1 lb/inch trunk diameter). Shade limits lichen photosynthesis.
• Don't use baking soda sprays—messy, ineffective.
• Don't scrub bark—damages cambium.

Healthy canopy = fewer lichens naturally.