United Kingdom 
how do i treat lichen on magnolia
1 Jun, 2010
Answers
Why do you want to treat it? Lichen is a sign of clean air and does no harm to the plant. However, it could be a sign that the canopy is not thick enough and the tree isn't growing very strongly. Feed it with an ericaceous plant food.
1 Jun, 2010
You don't need to, its' not harmful, but if you don't like the look of it, gently clean it off.
1 Jun, 2010