How to get rid of freakin Fungus Gnats!

turbo574March 12, 2011

Hey guys,

I grow tomatoes and peppers indoors and I got a bad batch of soil that apparently had Fungus Gnat larvae in it...givien I am indoors in an APT they are all over the place flying everywhere...

Dishes of water/vinegar certainly kills a portion of them but not before they lay eggs in the soil and produce their own bumper crop!

I am tried of trying to kill the flies and I want to kill the larvae so they are gone for good! But I wanna keep my plants organic so not pesticides allowed....

I have used Thuricide (which is apparently a bacteria used for killing certain pests) and it has helped a little bit...but alas I look in the soil and I see the little larvae all over the place if I look closely...

Any ideas?

I have thought about putting sand over the soil so they can no longer lay eggs into it....I have also though about and heard about predatory nematodes...but do not know how good they are...

Any ideas?

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Sticky traps for the adults. Allow surface of plants to dry a bit as well. Use pyrethrin-based household insecticidal sprays too.

    Bookmark   March 12, 2011 at 10:29AM
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Check this link for the problems you are having with Gnats.
Good luck and Happy Gardening!

    Bookmark   March 12, 2011 at 10:45AM
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BTi is the best thing I have ever found for fungus gnats. You mix it with water, then water your plants with it. You have to do it several times to kill all of the larvae in their various stages. Yellow sticky traps will take care of the adults.
If you can't find BTi in a liquid, you can buy a package of Mosquito Dunks. Put one of these in a gallon of water overnight, then remove it and use the water on your plants. You can reuse the leftover Mosquito Dunk for your next batch. Do this several times a week for 3 weeks. You can also buy Mosquito Bits (or crumble up a Mosquito Dunk) and put it on top of your soil. BTi is harmless to humans and pets.

    Bookmark   March 12, 2011 at 11:20AM
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timmy1(6a ri)

Knatrol...And a foliar pyrethroid at 4-7 day interval 3 times to break life cycle. Gnats are constantly hatching from larvae below soil, so just spraying only kills adults. And they are laying eggs shortly after hatching so you would have to spray daily or even hourly to kill them off.

    Bookmark   March 12, 2011 at 11:24AM
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taz6122(N.W. AR.6b)

1/4 mosquito dunk to a gallon of water. Water you plants with it after it sets over night.
I'm surprised tommy didn't mention that???

No harmful chemicals like pyrethroids.

Careful vgary. That looks like SPAM to me.

    Bookmark   March 13, 2011 at 1:18AM
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The Thuricide is BT....

Thought it doesn't seem to be long does it take after water the soil and spraying the leaves to kill off an infestation?

    Bookmark   March 13, 2011 at 3:16AM
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taz6122(N.W. AR.6b)

That's BT(k), you need BT(i).

    Bookmark   March 13, 2011 at 3:34AM
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I the variation makes a big difference?

    Bookmark   March 13, 2011 at 3:58AM
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A couple weeks of vaccuming every other day took care of the problem for me a few years ago. I would bump the grow lights firmly and start to suck. I tried sticky traps with little success. Did not use Bt.

    Bookmark   April 12, 2011 at 8:35AM
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All our house plants have 1/2" to 1" of sand in the top of the pot like mulch. We did that 2 years ago and have never had a gnats again. We where told they couldn't lay eggs in the sand. Give it a try.

    Bookmark   April 13, 2011 at 4:51AM
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