The garden still looks pretty good this spring, its mostly later-flowering species which are being damaged. |
Until this spring
I don't think I had understood just how damaging slugs and snails
could be. I mean, like most gardeners, I have had to fight the little
******s off vegetable seedlings and the occasional emerging
perennial, but never the wholesale onslaught the garden has suffered
this spring.
Prof. James
Hitchmough, up at Sheffield, always went on about them, a bit
obsessively, I thought. Now I see why. I remember Tony Kendle, an
academic botanist who went on to work at the Eden Project in
Cornwall, once telling me that he thought that localized extinctions
of native species could be caused by molluscs. So, they really can
have an ecological impact.
In my last garden,
we had very little problem, and in this one, not much of a problem
until last autumn when numbers began to build up. This spring the
numbers of the things are incredible, and exacerbated by a long cold
spring, in which the animals can operate, but many perennials are
growly only slowly, so they can be continually grazed as they emerge.
I am convinced now that they are capable of killing established
perennial clumps in these conditions.
They are highly
selective, and in fact the number of vulnerable species is actually
quite limited. I had already resigned myself to regarding some genera
as almost ungrowable because of them – Helenium might be one,
Asclepias certainly. Most of what I grow is actually unaffected. This
year though they have really gone for Veronica austriaca, many
asters, nepetas, aconitums, coreopsis, ligularia (well known snack) ,
baptisia, and most devastatingly, as it is an iconic plant in our
garden, joe pye weeds – Eupatorium fistulosum/maculatum.
It
is pretty obvious they can't eat anything with hairy leaves, but
there must be chemical defences some plants have which means they
don't get touched. Aquilegia and Thalictrum look very juicy and
defenceless but seem ok. Aster are odd: A. laevis for
e.g. is badly affected, but A. puniceus, novi-belgii,
novi-angliae all look fine,
Since some of these, like novi-belgii
and a couple of odd American species I am trialling are very
aggressive spreaders, they are going to have a clear ecological
advantage here.
What
to do? I'm very glad I did some research ages ago on good
old-fashioned metaldehyde slug pellets, as they are far the simplest,
cheapest and most effective way, and I can use them without feeling
eco-guilt. Several years ago, at a time when I was also questioning
the organic movement, I became suspicious that there was little
evidence of them being harmful to wildlife, I had phoned round
several conservation organisations, and none of them could come up
with any real links to wildlife deaths, Government statistics on
wildlife poisonings drew a blank too. Another eco-myth? James
Hitchmough was pretty sanguine about using them too, having looked at
the academic literature – he'd even done a research project which
involved students catching and identifying them at night (the things
you can make students do). Metaldehyde doesn't hang around in the
soil either. So a few pellets (you don't actually need very many) in
the crowns of vulnerable plants, leads to a satisfying array of dying
slugs the next day. Best in dry weather so they dry out quickly and
die 100%. Late evening slug hunts and lots of vindictive stamping are
effective too.
Longer
term, I think we may have to get the chickens in. Once vulnerable
seedlings are up and running, I'm hoping Jo will let the chickens
have free rein of the garden, and they can go round and gobble up the
next generation before they breed. But next spring I shall be ready
and waiting.