The gray-green "moss" is lichen—a harmless symbiont of fungus and algae. Soap doesn't remove it. Lichens proliferate on declining trees but don't cause decline. Focus on tree health: fertilize, prune dead/crossing branches, improve air flow. For winter-dormant trees, tribasic copper sulfate (4 tsp/gal) with spreader-sticker can reduce lichens, but avoid evergreens.
Healthy, vigorous trees naturally support fewer lichens. Address underlying stress factors.
Blue-Gray Growth on Tree Trunks: Lichens—Harmless, Indicate Light, Not Cause of Fruit Tree Decline
Lichen Is Harmless; Fruit Tree Decline Stems from Water and Soil Issues
Red Leaf Blotches on Chanticleer Pear: Getting an Accurate Diagnosis
Pine Tree Black "Fungus": Likely Sooty Mold from Insect Honeydew
Hypoxylon Canker: A Fatal Stress Disease of Post Oaks
Lichen on Japanese Maple and New Trees: Harmless Epiphytes, No Treatment Needed
Lichens on Trees: Not the Killer You Fear
Hawthorn Roots Near House: Fibrous, Non-Damaging
Florida Native Trees: ~90 Species, Live Oak Most Common
Poplar Copper Nails & Fir Topping: Stop Deep Fertilizing, No Wound Paint
Pruning Hemlock Trees for Hedge Shape and Size
Strange Fungus in Antique Furniture: Identification and Safety
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