We have noticed these numerous brown 'blebs' on the stems of a young olive tree bought from a garden centre. I have no idea what they are. They are clearly not part of the tree stem itself. Could they be a type of 'scale insect' which I gather can affect Olive tree? (wild guess!!!) Are they harmful to the tree? Where do they come from? Do we need to get rid of them. It is very difficult to detect any morphology on removing them.