Peter Jason wrote:
Thanks. I do know about the Clorox method and the other which is the
application of C12 quaternary compound (supposed to leave a retardant film
on the slate surface), but the only reason I have not tried these is
because I fear my gutters corroding. But I will try the Clorox method after
the Roundup (applied yesterday) works or not works. ncidently I have just
had my drains routed for roots (there were plenty) and the plumber said that
the terra-cotta drains were cracked and that I should flush some copper
salts down the toilet to dissuade future root infiltration. Before the
plumber arrived and while the drain was still backed up I emptied some
Roundup into it in the hope this might kill a large length of root.
Anyway, now I have a bag of copper sulfate next to the toilet and I throw
about half a kilo down the bowl twice a week followed by a half flush.

Do you know if this sort of thing works well?

Copper sulfate is the best thing for roots
in the drainpipe. It does work, though it's
illegal in many places here in the US.

Marine life is highly sensitive to copper and
since treatment plants don't remove it, so
keep that in mind and don't use more than
necessary.

I think that Roundup has to be applied to green
leaves and activated by sunlight. I doubt it
did anything in the drain.

My parents lived on the Pacific coast and had
a big moss problem on their roof. My dad used
rock salt and said it worked well.