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Organic insecticide help needed

Posted by mustgarden Zone 5 (My Page) on
Wed, Mar 7, 12 at 17:47

I have started hundreds of herbs and tomato plants under lights in my furnace room and all was going well until today, when a few little flying bugs turned into dozens. You can imagine what will be tomorrow if I don't act fast. I had been spraying a little insecticidal soap, but they're laughing at me. I read on this site that you might be able to use garlic in water or a little highly dilute?? horticultural oil. My plants are in the 1 centimeter to 3 inches range. Any suggestions?

Follow-Up Postings:

RE: Organic insecticide help needed

Beneficial Nematodes will eat the Fungus Gnat larvae.

Here is a link that might be useful:

RE: Organic insecticide help needed

Fungus gnats. Means the soil is being kept too wet. Are you using a fan for air circulation? If not you will find it helps a great deal in both keeping the gnats down. And, of course, cut way back on the watering. Most way over do it anyway and that is the most organic solution for eliminating the problem.

Otherwise several different organic based sprays are available including Dormant Oil spray (used only on the soil) and BTI (Bacillus thuringiensis israelensis) sold as Mosquito Dunks and Mosquito Bits under the Bonide brand.


RE: Organic insecticide help needed

  • Posted by morz8 Z8 Wa coast (My Page) on
    Wed, Mar 7, 12 at 19:21

mustgarden, if you have the fungus gnats now, I doubt if you will be able to let your seedlings dry out enough, for long enough, to get rid of the larvae without damaging the plants - better is to not keep your medium too wet to begin with.

I'd go with the BTi - Gnatrol, Knockout gnats, Bonide mosquito beater, or if you cannot find any of those locally, pick up some mosquito dunks and make your own solution - float a dunk or piece of dunk (no need to be precise) in a container of water overnight, then use that water to water your seedlings. It's not a 24 hour cure, it can take up to three weeks of consecutive use each time you water before you have broken the breeding cycle and are seeing no more gnats. Don't worry about the adults, they live just briefly, you want to stop their larvae, larvae that will feed on fine plant roots like the types seedlings are developing.

RE: Organic insecticide help needed

Thanks everyone. The fan is on and I will definitely be more stingy with the water. Tomorrow I'll see about finding one of the solutions you've suggested.

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