For the last three years the fruit trees in the nearest orchard haven't been sprayed with any chemicals at all. Admittedly some of the apples, pears and plums get some blemishes on them but they still taste wonderful and and make fabulous jam and sauces. On a more banal note the grey blue lichen reminds me of the trees that used to be on model railway layouts in the big departmental stores when I was a small boy.
One bonus, well it's a bonus to me if not the fruit farmers, is the growth of lichen on the trees. I don't know if it harms the trees but the lichen growths have created another fascinating small world.
The the trouble with lichen for me is that I know very little about it, except that it is there on the trees, so a book will have to be purchased to increase the knowledge bank a little bit. There's always the chance that I could be like the scientist in the John Wyndham book, discovering a serum that halts the ageing process.
I'll buy two books.