Dear Sir/ Madam, I have plum tree with some kind of disease, I dont know what it's called or how I should treat it , I have attached photos so please could you help me and advise me what to do. Thank you. Maysa
Certified GKH Gardening Expert
This is not a disease, but Lichen growing on the bark of the tree.
Lichen is not generally harmful to the host plant, though it can be an indication of growing conditions for the tree.