A rapid growing and easily-to-spread disease, trees all over the world host lichens--a common green fungus and mold-like growth. Over 13,500 species of lichens exist, thriving in the Polar Regions to the equator. Other green fungi and molds exist, but they either do not live on trees or are extremely rare or haven't been discovered yet.
Lichen is an algae and fungus working together to survive. The combination results in blue green tint or a greenish gray color. The growths resemble snowflakes, scales or antlers, depending on the species.
The lichens affect trees minimally. Non-parasitic, the lichens' presence indicates poor health and thin tree canopy.
Lichens spread by wind, making it hard to control and eliminate from trees. Lichens derive nutrients and minerals from the air.
Help your tree regain its vitality by putting 10-10-10 fertilizer around the base of the tree. Administer about one pound per inch of tree's diameter.
Add .4 pounds of baking soda to a gallon of water. Douse the affected area with the solution. This should kill the lichens. Moss-focused herbicide sprayed liberally over the affected area may also work.
Not all lichens mingle with green alga; lichen adaptability and diversity yield bright yellow and deep reds.