In message m, Scoby
writes
Our neighbour recently had a horse chestnut removed, now we keep
continuously getting growth (suckers) on our side of the fence.
Any ideas on how to kill it off short of excavating my garden to 10ft
and digging out the roots?

Try Ammonium sulphamate into the main stump -
Rootout (or something like that as a brandname).

Decomposes to fairly harmless nitrogenous fertiliser afterwards but be
sure to observe all the safety warnings on the packaging. Simple
chemicals that can kill entire trees are *not* user friendly. Tree roots
can be similar sizes to the obvious stuff you see up in the air. There
is a lot of stored energy.

Horse chestnuts are vulnerable to some nasty fungal infections which in
Belgium is causing an alarming number of old growth trees ( 100 years
old ) to fall down onto major roads. Not helped by Napoleons tree lined
road strategy.

Regards,
--
Martin Brown