The problem is that the DE sold for filtration purposes has usually been
thoroughly cleaned before packaging, and the washing rounds off the sharps
edges and points.

--

Ray Barkalow First Rays Orchids
http://www.firstrays.com
Secure Online Ordering & Lots of Free Info!


"Al" wrote in message
...
This is good advice for anybody building a greenhouse or an outdoor grow
area. It will help lower the numbers of many types of pests which find
food
and shelter in your orchids. Not just slugs, but mites and thrip numbers
can be lowered by a cleanzone. Keep brush and grass clear of greenhouse
for
several feet around it as part of an overall IPM strategy.

Of course, the material that you cover this cleanzone with is important.
If
you use mulch you are probably adding breeding spaces for snails and slugs
even if the lack of grass and plant material there will help keep down
thrip
and mite levels. Gravel would be the same, maybe a little better, since
slugs and snails will also make food of decomposing plant matter.
However,
either is better than plants or grass grown right up to the greenhouse
wall.

I use mulch in my cleanzone but I always poison it too. Several times a
year when it is really damp. I also spread bait and poison under the
benches for slugs that manage to get passed the cleanzone. Yet a few
always
do and always will.

Diatomaceous earth is suppose to work for two reason, I have heard. One,
it
has a lot of sharp areas which irritate the foot of slugs and snails who
might choose another direction if they encounter too much of it. And two,
it is made of a material which itself is an irritant to their tissue:
limestone and calcium. The problem with it, I suspect, is that it is too
low a concentration of "diatoms" and too high a concentration of "earth"
and
the slugs just go around the irritating part.

I have heard a good material for floors and cleanzones is crushed sea
shell.
Not just a mix of earth and shells but a real thick mulch of it. I think
this might be a more effective deterrent than diatomaceous earth, because
it
is just more of the same stuff that the organisms don't like walking on.

And all of these materials are only deterrents after all. They are a sign
that say, "slugs not welcomed here, go visit Al who just uses mulch for a
welcome mat." Diatomaceous earth and crushed sea shells are not poison.
They don't kill. They just irritate and make you seem an inhospitable
host
even if you are offering orchids and pepper plants for dinner and an
enclosed protected space where your monoped guests don't need to worry
about
critters that eat them, like birds and garter snakes.

100% eradication (control) is not possible even with a poison, of course.

For slugs and snails along the east coast this spring, while all the
conditions are right for a slug and snail population explosion and the
little fiends come bearing box cutters and explosives in their shoe, you
will probably need to use a whole arsenal of controls to keep their
numbers
down.

How does iron phosphate work on them? Is it a poison to them?

I am thinking that the damage to my garden from Japanese Beetles will be
much lower this year due to all this water. I figure a whole lot of grubs
have drowned this spring. Just looking for the bright side...



"K Barrett" wrote in message
et...
So I left a
clear zone of 2-3 feet around the GH so slugs would dehydrate before
ever
crossing this desert zone. Low and behold, they still made it in. The
suckers must pack for the journey.