Question
Hi Jennifer,
As a hobby, I recently started taking care of a small pomegranate orchard in Lebanon (Mediterranean weather similar to Spain. I just noticed, now in march, that many small twigs and even branches of some trees are covered by a green moss like structure. One can easily mechanically remove it. It almost looks like the olive tree warts, except that it is green and more shallow. I cannot spot any insects.I don't know if these are new or not, as this is the first year I  take care of this orchard. What do you think?
Thanks.
Tony

Answer
Hi Tony,

It sounds like the structures you are describing are lichens.  These organisms are not plant pathogens and are simply living on the surface of the trees.  They do not harm the trees and their presence is not a problem.  Usually, they will grow on branches that are most exposed to sunlight.  They can take on many different shapes and colors.  

For more information, you can review the informational sheet at the following web address:
http://ohioline.osu.edu/hyg-fact/3000/pdf/HYG_3312_09.pdf

You can also simply type "lichens" into your search engine and look at images to see many different types.

Good luck with your trees!
--Jen