On 07 Oct 2006 23:37:19 GMT, (Andrew
Gabriel) wrote:

In article ,
marvelus writes:
On Fri, 6 Oct 2006 13:42:35 +0100, "Andrew Mawson"
wrote:

However if you can get someone to install a thin taut bare copper wire
either side of the ridge, rain (which is slightly acidic) will form
copper salts which washing down the roof will kill the lichen

This is a myth.

Nope. There was a brilliant example next door to my grand parents.
Their bare phone wires passed over the roof of next door bungalow.
There was a very straight line across the roof some ~5' under the
phone wires were any drips would land. From that line all the way
down the the gutter, the roof was completely clear of moss and lichen.
Above that line, it was covered in both. That was the first time I
noticed the effect, long before I ever read or heard about it
anywhere else.


There is no evidence to support this nonsence. If you have any other
than some unsuported anecdote please share it. Otherwise there is no
way some insignificant dilutions of copper salts, which would be
washed away by the same rain thats supposed to be spreading them,
could act as a weed killer. The same sort of people who believe in
this probably also believe in homeopathy. Maybe your auntys neigbours
friends mother has a rabits foot tied to the tv ariel to kill the
moss.