Verdigris? Lichen?

Hi!

First post!

We've a number of very well established azeleas, but some are affected in places with this stuff on the branches. On one or two of the bushes, the leaves have a bit of "blooming" on them too.




It can be brushed off with a bit of effort and doesn't seem to affect the plant in any other way. Is there some sort of treatment for this or will a good spray of tar wash once the leaves have fallen cure it?
We've a fair bit of water near these bushes, a 3000 gall koi pool so I guess there's quite a bit of moisture in the air, added to that we live south of Manchester, but the climate, though it is occasionally rainy, is quite mild.

Any advice would be appreciated.

 

Doghouse it is lichen and is quite harmless and non parasitic but can look unsightly,it is as you say encouraged through high humidity,better air circulation in the area would help by pruning or cutting back some growth,it has no recommended chemical treatments.

 

Thanks for that, you've confirmed my suspicions. I might try brushing the worst off later in the year.

Much obliged.