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Thread: Is Neem oil Root drench suitable answer for fungus gnats?

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    Is Neem oil Root drench suitable answer for fungus gnats?

    So now I just saw 2 little black flies in my grow room. I am almost positive they are fungus gnats.

    I have read a lot about getting rid of these guys. However a lot of what I read was speaking about gnatcontrol or other products.

    I was wondering if a Neem Oil drench is a good fix to these bastards.

    I hit the plants with a neem oil spray 3 days ago when i was invaded by 15 or so ants. Then two days after the first spray I saw two gnats.

    How should I proceed.

    Can anyone tell me the ratio to use in my Neem Oil drench? If neem oil can be used to fight the gnats.



    Edit: I was reading about using potato slices to monitor the gnat larva in the medium. If I were to take action against these gnats. Is it best to do all the pots or only the ones I believe to be infected? I was thinking of using the potatos to find which pots actually have larva. However they say this could take up a to a week to start seeing larva in the potatoes.

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    420 Member Tmac12's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    Gnats are tuff. They fly around and lay eggs, the damper the soil the better for them. They actually crawl up the holes in the bottom of the pots and lay eggs. The eggs hatch into these tiny tiny maggots, that change into the flys. I have used sand, neem, DE and am still fighting these. Now using permetrol. YOU HAVE TO TREAT EVERYTHING, ALL POTS OF ANY KIND OF PLANTS. When you treat you are only killing the live gnat and larva. You still have to deal with the eggs, gotta keep watch and retreat as soon as you see some gnats. Not sure my plant will make it at this point. It is a vicious circle!! Hope some of this helps.

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    420 Member airavata's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    Hey, Bill. The bottle your neem oil comes in should tell you what rate you should mix it at. I've been mixing it at one oz. per gallon. I'm dealing with gnats too. A root drench with neem shouldn't give you any trouble. It may or may not kill all the gnats in your room. I've heard a lot of people say this or that brand is the only one that works. I've never heard anyone mention the brand I use and it kills most of them. In veg, I spray all the foliage as well to make the environment as inhospitable as possible for them. You should spray them with water the next day to unclog their stomata. You will want to repeat the process in 3-5 days to get any newly hatched larvae. In my experience this doesn't remedy the problem completely but it does keep populations in check.

    Other methods I've heard work well but haven't had the chance to try are:

    -beneficial insects that feed on gnat larvae (parasitic nematodes, ladybugs, certain flies)
    -sprays that disrupt the insects' life cycle (I haven't looked into the safety of this, personally)
    -pantyhose around the bottoms of your pots with a layer of perlite covering the soil at the top is supposed to keep gnats from getting into the soil to lay eggs
    -diatomaceous earth can be dusted on your foliage and will kill gnats that walk across it due to its physical structure and is non-toxic (so I hear)

    I would suggest supplementing the neem method with one or more of the other options I've listed. It is definitely a good idea to be proactive. Gnats can be a serious problem.

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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    Thx Air,

    Yea I had a bottle of 70% neem solution from a previous grow.......however the label kinda peeled off and the company website wasn't very helpful.

    Right now Im spraying everything every 3 days........Ive killed a total of 4 gnats so far spread over 6 days and havent seen anymore. Im just going to keep spraying for a couple more weeks if this doesnt work then I will probably do a root drench and buy some other stuff.

    I think I might retry the potato thing again........however I really didnt like the idea of rotting potatoes in my garden.

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    420 Member airavata's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    No problem. Sounds like you've got it under control. Just keep in mind that if you start seeing their numbers increase, that they're breeding in your soil and their larvae are destroying your roots. It doesn't sound like you're facing nearly as bad an infestation as I had BUT once you realize you have an all-out infestation, your plants' root structure is already severely compromised. Personally, I would err on the side of caution and do the root drench.....maybe 3 times over the course of a week and a half. It won't hurt them. You can probably mix your solution at just under 1.5 oz (1.3 oz. to be more precise) per gallon of water. I wouldn't try the potato thing, but that's just me.

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    420 Member Tmac12's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    I think I actually have some new growth on Sassy. Again no gnats this morning. I should get my azamax today in case they hatch again. Gonna take some photos and post them in a little while.

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    420 Member GreenChrome's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    I have these gnats too, I transplanted 4 out of 5 plants to smart pots (no holes in the bottom) and the population mostly died off. The remaining guys have ben hanging around the drainholes on the remaining pot, so I transplanted that one today and used the same root drench to get rid of them for good, hopefully. Good Luck!
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    420 Member Tmac12's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    They seem to hatch out about every 3-5 days, plant on drenching again and maybe again. I got me some azamax finally. Hope to put them out of my mind soon!!! I seem to have gotten them under control right now but dont ignore them for a minute... it is a circle, they breed, they lay eggs, they hatch,,,,

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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    Yea every 3 days seems about right. I think I caught them early because I haven't seen 1 for 3 days now so well see tomorrow. Probably going to root drench as well just to be safe.

    Ive also trained a daddy long leg spider I named him Spiderman He has the taste for their blood now.

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    420 Member GreenChrome's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    I wish I could find some daddy long legs around here this time of year...
    Peace, my friends!

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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    If you have a gnat problem in soil, you are pretty much over watering.

    I've never had a gnat problem, but I also let my plants dry almost to the point of wilting.

    Gnats love an overly moist medium.

    DD
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    420 Member Brett2theMax's Avatar
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    Re: Is Neem oil Root drench suitable answer for fungus gnats?

    1/4 tbsp of crushed up Mosquito Dunk's, I haven't tested it yet but I have seen some gnats sprout up so I'm about to I've read nothing but good things about this treatment.
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