My Least Favorite Pesticide

People often ask me about the most dangerous pesticides — the ones which they should be careful to avoid.  There are lots to choose from:  Di-syston (aka disulfoton) is really bad.  Rotenone has some potential problems that make it scary, as does copper sulfate.  But for my money the worst thing out there is something that isn’t even supposed to be used as a pesticide (at least not anymore) but which finds its way into our gardens thanks to recommendations from people like Jerry Baker:  Tobacco.

Despite its obviously “natural” origins, tobacco isn’t allowed by organic growers because of its drawbacks which I’ll mention below, but because it finds its way into so many “how-to” books it’s definitely worth knowing about this beast.

It’s easy to buy chewing tobacco, mix it with a little water, and apply it to whatever aphids or other insects that you see.  What’s even better is that tobacco really does work (just like Jerry says!).  In fact, for some things it works great.  For example, I’ve tried all kinds of barriers against slugs, and tobacco is the one that works the best, hands down — copper is kinda OK, diatomaceous earth takes a while but works fine — but man, tobacco really throws slugs for a loop.  Watching a slug try to go through a pile of tobacco is terrible (and yet morbidly entertaining!)  First, the slug approaches the tobacco at a snails pace (the snail is a close relative of the slug!)  Then the slug touches the tobacco….and then the fun begins!  The slug starts to move really fast — literally mouse walking pace — and then it stops — and then it shakes — and then it dies.  This all happens within four minutes.  The slugs in the picture below are all dead.

Despite my success I have a hard time recommending tobacco for slugs for two reasons.  The first is that it can carry plant diseases which can cause some major problems, and the second is that some dogs like to nibble at the tobacco — and they won’t let you know they’ve nibbled it until you let them back into the house (if you know what I mean)!

When a tobacco spray is used for insects the process is a bit different than just placing tobacco on the ground.  First, you mix tobacco with water, let it soak for awhile, filter the water out, and then spray it on the insects.  In the old days — the 1800s when this type of spray was popular — they would mix about a pound of tobacco with a gallon of water.  Jerry usually recommends much less.  The problem with recommending less than this is that at lower concentrations it doesn’t work nearly as well — but you really wouldn’t want to apply more because then the spray starts to get dangerous (because of higher nicotine concentrations).  So it’s a catch-22.  Don’t underestimate the toxicity of nicotine!  Also avoid underestimating the nastiness of the plant viruses that this stuff carries.

So what should you use instead?  A good insecticidal soap, or a spray with water are what I like to recommend.  If you must use something stronger then look for an insecticide with the active ingredient permethrin and follow the labeled instructions carefully (also make sure that the insect you want to control is on the label — if you can’t identify the insect you’re trying to control, or if that insect isn’t on the label, then don’t use a pesticide).  For slugs my favorite pesticide uses the active ingredient iron-phosphate.

14 thoughts on “My Least Favorite Pesticide”

  1. It continues to amaze me that people think because something is "natural" that means it's "safe." Plants have to use biochemical warfare to survive – because they can't run away. Nice post, Jeff…though your description of slug death by nicotine made me laugh even though I knew better. Kind of like a Tarantino movie.

  2. I've used the copper stripping technique on my vegetable beds to great effect! Due to my ethical philosophies I prefer not to kill pests in my garden at all – encouraging a diverse ecosystem is by far the best pesticide one can introduce into their garden!

  3. This message just can't seem to be said enough to reach people. Nicotine is a poison (I tell people it was a popular method in English murder mysteries). Jerry Baker is a retired cop – definitely not a horticulturist, or even a real master gardener. Homemade concoctions are often either dangerous, damaging to plants, ineffective, or more expensive. Oh, and plants really aren't like people at all! /rant

  4. I've noticed that my hostas are less slug-prone when I've put down a fresh layer of wood chips in the spring. I think the rough texture might encourage them to visit the neighbors' gardens instead.

  5. Jimbo,I wish everyone were like you! Things which are rough sometimes seem to slow down slugs, and sometimes they don't. Besides diatomaceous earth I don't know of any sharp object which can really hurt a slug (they can crawl right over a razor blade). I've tested many things as slug barriers. The only ones that work consistently are diatomaceous earth and tobacco. Even copper fails as often as it succeeds. One thing that I should note is that slugs usually work in cycles. One year an infestation will be bad followed by two or three good years (this is probably because of a buildup of natural predators/disease). Lots of people interpret this to mean that their techniques are working when they aren't (I had one person tell me that lint worked! — I tried it — it doesn't — in fact, they seemed to like it…)

  6. Jeff, I'm wondering about parasites or egg predators of slugs? I see so few now that I'm wondering if my lovely mulch is supporting slug controllers. I just don't know much about what eats slug eggs, or parasitizes adults.

  7. Oooof! You're asking the wrong person…I can certainly speak to their cycles (my garden and many others in the area have them), but I'm not sure about exactly what kills them (I also wonder what the differences are between WA and MN…).

  8. Great comment about not using a pesticide if you can't identify a supposed pest. I've had someone tell me they could recommend an herbicide for that broad leaf weed in my lawn while pointing to my (deliberately planted) clover!

    As far as slug predators I know of at least two – brown snakes and opossums.

    I heard about a study out of (I think) Wake Forest University that showed that the number of brown snakes increased after the accidental introduction of a European garden slug. The European variety caused an increase in the total number of slugs and the snakes followed.

    Opossums will eat slugs and snails (and that's a funny sounds to hear after dark – the crunching of snail shells between opossum teeth). The best thing about opossums is that they are not territorial and will generally move on in a few days. So they'll swoop in, reduce the number of slugs and snails (and snarf up any overripe fruit or pet food left outside) and then they're gone.

  9. I like "Sluggo" too — iron phosphate with malt (? I think?) but I usually use it only in spring when foliage is emerging. Once the plants are large enough, slugs aren't as much of a problem.

    I also get regular nighttime visits from skunks and I believe they eat slugs. (At least I hope they do — thinking so certainly helps with odor tolerance!)

  10. You must be from WVA! Sadly I have no idea what folks mean when they say "If you know what I mean." Say it! What do you mean?

  11. No, not from WVA (Minnesota actually — haven't you ever heard of Minnesota nice?), but I'm happy to clue you in — and sorry that I didn't make myself clear in the first place — diarrhea and/or vomiting is common in dogs that have eaten chewing tobacco — and worse is possible depending on how much they eat.

  12. I am a major predator of slug eggs when I empty containers and leave all the slug eggs on the driveway for any critter that comes by. Regular fall exercise.

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