GardenBanter.co.uk - View Single Post

06-05-2006, 05:08 PM posted to uk.rec.gardening

The message
from (Nick Maclaren) contains these words:

In article ,
K writes:
|
| I have recently been told the same 'poisoning the ground' theory about
| horse chestnuts.

Which brings to mind the good ol' Yankee expression "horse puckey".

It is true to some extent for conifer and yew needles, and to a very
limited extent for some deciduous trees (e.g. SOME walnuts), but it
is a suburban myth to believe that it is a widespread phenomenon or
stops ALL plants from growing. Some plants will grow even under
conifers, though not in a conifer plantation.

Some trees and shrubs do manufacture and disperse (through fallen
leaves) chemicals which are toxic to other plant species and prevent
their seed germinating in the affected soil beneath. Rhododendron
ponticum, walnut and some eucalypts are in that category and I believe
horsechestnut are too. It's just one of the means that makes Rp such a
successful coloniser. Even if dense colonies of it are felled and
removed, it will be many years before the toxins fade sufficiently for
other species to seed into the bare soil left behind. (Rp seed is not
affected, of course).

Beech is not one of the trees that has that effect.

Janet