Botanic Garden >> Gardening > >> Question and Answer >> Plant Diseases

Lichens on Prairie Fire Crabapple: Cosmetic, Not Harmful

Crabapple Covered in Lichens and Silver Moss

Tree healthy and blooming, but owner worried about lichen/moss coverage.

Expert Explanation

Lichens are algae-fungi symbionts; epiphytes, not parasites. Three forms: crustose, foliose, fruticose. Common in high humidity. Slight negative effect: indicate thin canopy. Best control: improve tree vigor for denser shade, which suppresses lichen photosynthesis.

Fertilization Advice

Apply 10-10-10 at 1 lb per inch trunk diameter. Baking soda spray (0.4 lb/gal) mentioned but not recommended.

Plant Diseases: Lichen on Mulberry Tree: Symptom of Underlying Stress; Black Walnut Fern-Like Growth: Harmless Lichens, Not a Disease; Plum Tree Sudden Decline in Drought: Fire Blight or Borers?; Lichens on Trees: Harmless Indicators of Stress, Not Disease; Black Blotches on Mulberry Trunk: Likely Lichens, Not Disease; Sugar Maple Lightning Strike and Lichens: Damage Assessment; Fire Blight on Lemon Tree? Unlikely—Look for Other Causes; Green Shamrock-Like Growth on Trees: It’s Likely Lichen, Not a Threat; Lichen on Flowering Crabapple: Harmless Indicator of Tree Stress; Gray Marshmallow Masses on Tree: Harmless Lichens

Garden Articles

Blue-Gray Growth on Tree Trunks: Lichens—Harmless, Indicate Light, Not Cause of Fruit Tree Decline

Green Growth on Old Pecan Trees: Resurrection Fern or Lichens

Lichens on Weeping Cherry: Harmless Indicators of Thin Canopy

Christmas Tree Fire Damage: Water, Wait, Prune Dead Later

Lichens on Trees: Harmless Epiphytes or Hidden Threat?

Gray Fungus on Large Trees: Lichens, Not a Disease

Lichen on Orange Tree: Symptom, Not Cause

Plants

Fire Blight on Loquat: Pruning and Streptomycin Protocol

Green Growth on Fruitless Mulberry: Lichens Explained

Greenish-White Scale on Oak: Lichens, Not a Disease

Black Trunk on Live Oak: Natural Aging or Lichens?

Light Green Growth on Pineapple Guava Trunk: Likely Lichen

Magnolia Bloom Failure and Trunk Lichens: Nutrition & Cosmetics

Lichens on Crape Myrtle: Identification and Non-Chemical Management