Thursday, April 11, 2013

Snail & Slug Prevention AKA DIE SLUGS DIE!!!

Snails and slugs are an annual problem for gardeners.  Your plants are looking great one day and the next they're full of holes and slime trails, and tender fruits like strawberries are devoured.  On the list of gardening things that anger me, these bastards are near the top.  (Rabbits are still worse, they start out all cute, fuzzy, and innocent until one day... BAM!  Just like that they become crazed mammalian plant destroying machines.  But that's a topic for another time.)

How to control them is the big question.  There are lots of answers.  Personally, I don't have time to mess with beer traps or night-time forays into the garden to hand pick them from plants.  Not that I mind night-time forays into the garden, but I'm not doing it to pick slugs.  I'd rather pick strawberries.

Being a Hosta guy with over 300 varieties, controlling these evil menaces to society is important to me.  I want people to come over and say, "hey, nice Hostas" rather than "oh, you have slugs eh?"  In the ornamental gardens, I use Sluggo Plus or Espoma Earth Tone Bug & Slug Control.  They are basically the same product, containing Iron Phostphate and Spinosad as active ingredients, I generally find the Sluggo brand to be cheaper.  Spinosad helps to get rid of other pests such as earwigs as well. 

This year spring is behind a bit, so I haven't done an application yet.  Generally I apply the granular baits as soon as the snow is completely thawed.  This is usually mid-late March here.  An early application like this will kill snails and slugs when they start to become active, before they have the chance to create more little hellions.  I do a 2nd application in early May, to kill any survivors of my initial onslaught.  Usually this will keep the population down through the summer, though new snails and slugs may migrate from the surrounding areas.  I also do a fall application in September to knock down the population of new snails and slugs that may decide my gardens make a great place to overwinter.  Welcome to the Bates Mollusk Motel.

Both of these products are OMRI listed organic and advertised as safe for kids and pets, but there is some debate to whether they are actually safe or not.  One of the unlisted inactive ingredients is EDTA.  EDTA is a chelating agent used widely in cosmetics, the medical field, and even in food items; by itself it has a fairly low acute toxicity and a low incidence of organic pollution.  Iron phosphate, one of the listed active ingredients, is even safer for use and is present in large amounts in the environment and generally considered non-toxic.  It's even non-toxic to snails and slugs.  So how does it work as the active ingredient?  By combining it with EDTA, the combination breaks down in the gut of the organism that ate it, releasing a lethal dose of iron in the form of FE3+.  There's a long and interesting article about it here.

The other active ingredient, Spinosad, is an insecticide that is derived from bacteria and has a unique mode of action.  I won't get into the boring details, but unique modes of action are generally a good thing in the pesticide world.  It tends to be difficult for insects to develop resistance to such insecticides.  Spinosad is highly toxic to bees when sprayed directly on them, but dried residue shows very low toxicity.  Spinosad has high efficacy, a broad insect pest spectrum, low mammalian toxicity, and a good environmental profile.  There has been one study that showed an increase in mutagenic tendencies in rats given a daily oral dose of 37.38 mg for 60 days.  It should be noted that this is far above the acceptable daily intake of .02 mg.  I'll still happily use spinosad for organic gardening after reading the above study.

So what about vegetable gardens?  Well, if you don't have kids or pets and you don't accidentally ingest these baits, you should be fine.  They will still break down to fairly harmless organic chemicals in the environment.  For our vegetable garden, we use Diatamaceous Earth.  DE is the fossilized remains of a specific group of algae.  These fossilized remains are very sharp and will slice into the soft bodies of snails and slugs, as well as deter harder bodied pests.  It's a very satisfying thought isn't it?  It's been fairly effective for us and it's affordable and easy to apply. 

So what's your favorite method of snail and slug eradication?

1 comment:

  1. The slugs are already out like crazy. Was very surprised today when we moved some wood that had laid on the ground since Mon/Tue and some of the pieces were COVERED in those nasty lil things!

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