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A Growers Journal: Turning to Gnatrol to get rid of fungus gnats

Turning to Gnatrol (Bti) to get rid of Fungus Gnats once and for all

If you recall, a few months ago I wrote of how Kmart sold me a bag of potting soil with fungus gnats, and soon every plant in my house and office seemed to be infested.

detailed every single tactic I found to try to get rid of them. I tried drying out the soil, but even after all the dirt was bone dry and the leaves started to wilt, watering seemed to bring back the gnats with a vengeance. I tried sprinkling cinnamon but gnats keep showing up. I bought 100 Yellow Sticky Traps, enough to put and put 1-2 on every single plant. While they do a great job of trapping adults they don't seem to be stopping new larvae (remember that it just take one gnat to get through the perimeter alive to lay 200-300 eggs). Finally, I went to both Gardener's Supply Company and Amazon to buy nematodes; none of them seemed to work the first time around which I attributed to them being fried during shipping. But even when I requested replacements, they didn't work either. Drenching the plants with Hydrogen Peroxide didn't seem to do much either.

No more Mr. Nice Guy. It was time for me to turn to Gnatrol. (I found Gnatrol for a reasonable price online) I've admittedly been resisting this option because I've heard that Gnatrol is a "pesticide", and I wasn't keen on adding "dangerous chemicals" to my plants. After all, the point of growing these plants is for me to clear the air, and the last thing I need is for my plants and soil to be poisoning me.

But that's when I did my research. At first glance, Gnatrol sounds scary. It's a "larvacide" with an active ingredient called "Bacillus thuringiensis subsp. israelensis", or Bti. Did I really want to put bacteria into all my houseplants? I mean, putting live parasites (the nematodes) was freaky enough an idea to get used to. The song "I know an old lady who swallowed a fly" kept ringing through my head.

But after reading more about it, Bti is as close to a miracle fix as modern science has come up with. First of all, what they sell isn't live, viable bacteria; the toxicant that kills the larvae is actually a part of the Bti spore. It was actually discovered in 1976 in Israel from scientists who isolated the bacteria from dead mosquito larvae. It's a substance that's deadly to mosquito larvae (as well as larvae of blackflies, midges, and fungus gnats). Specifcially, Bti releases special protein crystals. When the larvae eat them, the alkaline nature of their digestive system causes these crystals to dissolve and be converted into toxic protein molecules that destroy the inside of the larvae's stomach. Long story short, they can't eat and then they go off to that giant Golden Pothos in the sky.

Here's the cool thing about it--because humans, animals, birds, and fish have acidic and not alkaline digestive tracts, the Bti toxins don't have any effect on us. In fact, Bti is used in mass quantities by cities and municipalities worldwide to control mosquito populations. Because it's a bacteria that's found naturally in soils anyway, there's less fear of using it than more dangerous chemical solutions. Another thing that's nice about Bti is that once it's released, the active ingredient will dissipate after about 72 hours, so even if it were harmful to humans, the exposure is limited.

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