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

Green Flat Fungus on Oak Trunk: Likely Lichens—Harmless, but Photo Needed for Certainty

Initial Assessment

Flat green coating on 9-year-old oak trunk in Daytona Beach = probably lichens (harmless). But need close-up photo to rule out algae or early fungal canker.

What to Check

Tree vigor: yellowing leaves? abnormal drop?
Photo: sharp, close-up, preview on computer before sending.

Why It Matters

Lichens need light—common on exposed trunks. True pathogens show canopy symptoms. Photo confirms.

Plant Diseases: Sapsucker Damage on Oak Trees: Identification and Management; Oak Trunk Green/White Growth: Lichens, Not Disease; Woodpecker Damage and Borer Infestation in Willow Trees; Oak Leaf Galls: Wasp-Induced, Cosmetic Only; Evaluating Decay and Holes in an Old Oak Tree; Oak Trunk Fungus (Conks): Decay Fungi Management; Black Wet Areas on Oak Trunk: Borer Damage, Not Fatal; Dark Clusters on Oak Branches: Insect Galls, Not Fungus; Decay Fungus Conks on Red Oak: Not an Emergency; Orange Mushrooms on Oak Trunk: Decay Fungus, Not an Emergency

Garden Articles

Sapsucker Damage on Young Oak: Same Culprit, Different Tree

White Powdery Growth on Oak: Powdery Mildew or Insects?

Orange Bumps on Oak Leaves in Florida: Likely Gall Insects

Bark Lice on Florida Oaks: Harmless Webbing Insects

Silver Oak Termite Damage: Internal Decay Likely Terminal

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

Bark Lice Webbing on Oak Trees: Harmless but Startling

Plants

Is Your Old White Oak Tree Healthy? Understanding Loose Bark and Fern Growth

Lichens on Oak Trees: Harmless Epiphytes or a Sign of Stress?

Nuttall/Shumard Oak Lichen: Not Harmful but Indicates Stress

Oak Leaf Fungus at 5000 ft: Cosmetic Leaf Spot Management

Oak Twig Drop & Bark Discoloration: Twig Girdler/Pruner Beetles, Harmless Bark

Fungus on Carved Oak Stump: Slow Decay with Bleach Treatment

Oak Borer Infestation: Assessment and Neighboring Tree Protection