What kind of lichen? Are they cutting out light/air movement or????
I have lots of lichen on fruit trees here but never found them to be a
detriment. At one point I was convinced that they provided harboring
places for insect pests, but observation revealed that birds where
delighted to take care of that issue, and those trees with lichen have
consistently performed as have those without.
So am curious about why you'd fool with getting them off/out. We do
have different lichen here than down there, but the biggest differences
are in the ground/rock dwellers (almost no umbilicarias here, for
instance, and plenty more of 'red soldier' or 'British troop' types
here, sometimes covering an acre or so). We have in trees many of the
cup types and some of the 'beard' sorts, but they don't get as long as
in the south, although I think that is as much because the wind rips
them off as anything else; in areas protected from the wind they get
fairly long.