How to Kill Roof Lichens

Lichens, which are technically a symbiotic association of algae and fungi, are green growths that appear on tree bark and, more problematically, on rooftops and other structures. Although lichens by themselves do not pose a serious threat, they may be considered unsightly. As lichens consist of fungus and an algae that require each other to survive, if one is killed the other will die. Thus, the lichen can be destroyed with either a fungicide or a treatment for the algae.

Copper sulfate or zinc-copper sulfate mix powder
Water
Wet applicator (if desired)
Scraping tool

Instructions

- 1
  Wet the area with the lichens. This is unnecessary if the copper sulfate is being applied as a solution with a sprayer or wet applicator. Additionally, wetting is not necessary if the roof is wet immediately after a rain event or from dew.
- 2
  Sprinkle the copper sulfate on the problem area. Follow manufacturer instructions and take all safety precautions as instructed while using the powder. Or, apply the copper sulfate with the wet applicator. Leave the copper sulfate on the roof for an extended period. The copper sulfate may require several weeks to effectively kill all the lichens.
- 3
  Scrape off the lichens after they are dead and can flake off with minimal effort. The entire lichen growth may be removed easily or will fall off on its own within a few months.

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