Question
I was doing some research on lichens on Google and all I came across was how beneficial they were.  But I have these green looking what I call lichens that are starting to grow on my roof asbestos shingles and I would like to eliminate them without damaging the shingles.  Do you know how I can get rid of the ones of have?  I was thinking of using bleach, but didn't want to change the color of the shingles.  Thank you for your help.

Answer
No products are labeled for lichen control, but copper fungicides labeled for ball moss, or the home remedy of baking soda (sodium bicarbonate) for ball moss control (label pending) are detrimental. In pecan orchards, the fungicides used for scab and downy spot control reduce lichen numbers due to their effects on the fungal partners in lichens. I would not use bleach although a weak bleah solution is used to control mildew on painted outside sutfaces. You could try it on a small area to test if it would stain the roof. I think I would try baking soda or a copper fungicide first on a small area to make sure it did not stain the roof. Both should be ok and control the lichens.