Re: echinacea and slugs

david feix wrote:
> 
> --- Anthony Lyman-Dixon
> <lyman@lyman-dixon.freeserve.co.uk> wrote:
> 
> > Do you get slugs in California? they devour every
> > Echinacea we put out
> > in England and would love your mulch, but in one of
> > the tunnels that is
> > too dry for them, the Echinacea purpurea are more
> > than five feet tall.
> > Anthony
> >
> 
> We certainly do have slugs here in California, though
> they are less of a problem in hotter inland areas than
> nearer the coast where the fog keeps things moister.
> Here in my own Berkeley garden, I have noticed that
> since I put down new mulch in one virtually unwatered
> bed, that the slug numbers have increased explosively,
> such that I had to bait for the first time.  They were
> devouring my succulent Graptoverias, which perhaps
> were more prone to such damage for being grown in deep
> shade.  The same plant in same mulch conditions were
> untouched in full sun areas.  They were also eating
> the succulent Graptopetalum paraguayense, which is
> normally immune to attack.  I don't know about
> Echinacea being fatally attractive to slugs here, as I
> don't grow it.
> 
 David 
I wonder if there is a possibility that while mulching for the first
time would cause a sudden rise in the slug population, this might
correct itself naturally after a time.
 
I am lucky that slugs (or much more commonly snails) are only a very
occasional severe problem in my garden, especially on some of their
particularly favoured plants like Hostas and Arthropodiums and on things
in containers outdoors waiting till spring to be planted out (They can
shelter between the pots if one is not sufficiently diligent). In the
veg garden.  where I have mulched every bed (summer and winter)for
upwards of twenty years, I often find small snails or the odd slug
during winter sheltering in the folds of celery or under the leaves of
winter chard or other greens, but the only time in many years I can
recollect any serious sign of damage was one spring where I began to
lose young broccoli transplants bitten off near the base. I simply
applied a sprinkling of diatomaceous earth round the remaining plants
and saw no more damage.
 
A few of my observations on the frequency of snail attacks:-

1) In one particularly bad season, when in spite of traps my
Arthropodium plants (mulched) had their leaves shredded, the same
species in the gardens of Government House in Wellington (which I
visited that spring with the Institute of Horticulture) were equally
badly damaged although NOT  mulched.
This was also the season when I found literally hundreds of  (mainly
large) snails sheltering under the plastic covers of my compost bins and
duely made them into compost. What made tham so bad that year was a
mystery, as we had had a quite normal mostly dry summer. It was not that
spring eitheer but a later one, with little other trouble, that the
damage to the broccoli occurred.

For the following several years snails were at a low ebb regardless of
weather and mulching, but this winter there has been  a new buildup,
which I suppose one might ascribe to  an extremely unusual wet summer
followed by a normally wet but exceptionally mild winter. So far there
is little damage but baby snails are everywhere on the winter
vegetables. In addition a couple of months ago I began to see damage to
the fruits on the one tomato I grow in the glasshouse and a protracted
snail hunt over about four weeks finally rooted out the entire gang of
close on 200 small snails, which were hiding among the thick foliage.
Since then I have found a few stragglers, but at last I think I have
them all and general damage to other things in the house as well as  the
very last of the tomatoes thankfully seems to have ceased.

What I think I am trying to say is that, while one can in this patch
perhaps see some correlation between epidemics of molluscs and unusually
wet weather, I have no firm evdence that in my garden mulching actually
makes an appreciable difference. What is the real factor which causes
the level to fluctuate markedly from year to year I find quite unclear.

One other point, while there are native species of both slugs and snails
here, they almost never come into gardens, being  adapted to life in the
bush and most of these local snails are in any case carnivores.

So all snail and slug damage in gardens can be traced to imported pests,
and like most of such they came here without any natural enemies apart
from a few birds which were brought in also (but deliberately rather
than by accident!)..  What I am wondering is, if the slugs causing your
problems are indigenous, what creatures should be controlling them?
Perhaps it is one of these cases where civilization has destroyed the
natural checks and balances in your area.

Moira

-- 
Tony & Moira Ryan,
Wainuiomata, North Island, NZ, "two and a bit" islands surrounded 
by water in all directions - 5000 miles to Chile to the east,
Australia 1500 miles NW, South Africa 6000 miles to the west.
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