Fungus gnats organic grow help

Budley Doright said:

They drove me to hydro indoors and haven't looked back. God damn things drive me nuts. I think OP better look at other pests if the leaves are being eaten though, never had that !

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So you don't have the issue with gnats while growing hydroponically? Was thinking if I should switch to hydro for next grow but not sure. How are you liking it opposed to soil?

Jubilant said:

Diatomaceous Earth (FOOD GRADE) destroys them and won't hurt your microbiology even a little. (It's even used as a soil conditioner by some for it's water retention and micro nutrient levels) Make sure to let the top of your medium dry out between watering and just mix the D.E. into the top 1/4" or so. Life cycle is about 10-14 days for these guys so if you can keep the top dry and D.E. laden the larvae will die by the D.E and the adults will all die without being able to breed. When ever I get new EWC from the store I get new fungus gnat and I just do this and continually foliar spray with just water to assure the plants are getting some water in this time. Never had it not work.

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Yes! I love this stuff!

guy6969 said:

So you don't have the issue with gnats while growing hydroponically? Was thinking if I should switch to hydro for next grow but not sure. How are you liking it opposed to soil?

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No not a one . I grow outdoors in soil in summer and indoors in winter and love both .

Are fungus gnats a common occurrence with organics? This is not the first post I've read about this. On another site I was trying to help a guy who I thought was incompetent because he couldn't get rid of them. I'm in a soiless mix 50/50 with perlite and I've only had the problem once. Of course it was due to overwatering. But they were easily killed and eliminated. And I learned not to overwater really fast and haven't seen them again. But this guy said he fights them every time and couldn't get rid of them. I gave up because I really thought he was slow! I suggested to him there could be something in his organic mix that was a magnet to them?

The gnats can only reproduce in wet rotting soil. If you run a proper dry cycle and dry up any residual water and don't have high humidity you should not have a gnat problem.

And they don't chew leaves as mentioned a few times here. The larvae eat the roots which causes necrosis eventually.

2 inches dry is a bad rule. What size pot? How is the drainage? I like 3/4 dry down the pot as a rule better.

What do you guys put at the bottom of the pot to stop them there? I had them coming out the drain holes as well. I would let the top dry but that did nothing for the bottom. I tried dimascus earth but nope lol.

Budley Doright said:

What do you guys put at the bottom of the pot to stop them there? I had them coming out the drain holes as well. I would let the top dry but that did nothing for the bottom. I tried dimascus earth but nope lol.

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You can kill them all off with mosquito dunks in your water but unless you can leave the pots to dry out way more regularly they will likely come back.

The environment needs to become inhospitable to the gnats.

I have left a mature 5 oz yielding flower to dry for 5 days before the upper leaves began to wilt. It came right back when watered. Or I wouldn't know it was 5 oz.

I started panicking at 3 days but the pot was never light enough til after 5. Now I know what to feel for weight more.

guy6969 said:

So you don't have the issue with gnats while growing hydroponically? Was thinking if I should switch to hydro for next grow but not sure. How are you liking it opposed to soil?

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This whole thread is entertaining as hell. First off, his problem is something eating new growth and close to it, leaves...correct? Like it has been said. It ain't fungus gnats!

You can get fungus gnats with hydro! They work the hydroton zone well. Same for rockwool and soilless.
I'll bet they came in by way of eggs in Budley's soil, when he did soil growing. Fox Farm soils have been known for this for about ever!

Everybody and their brother has a way to control or kill off fungus gnats...First thing is proper identification of the pest. I always have yellow and blue stickies out! If I find a bug stuck to it. I look at the sucker through a 60-100x scope and be sure what I'm about to fight is what it is!

Letting it dry out is always a place to start. Yet, gnats seem to give folks problems.

First off, calm down. Fungus gnats do little damage at all. They are more of a "pest" to you, then your plant. Unless of course you ignore them and they go ape shit all through your garden....

Many who say that "this or that" didn't work for me....Simply did not treat in a way to actually "break" the cycle....
Dunks are popular.
D. E. is too.
I don't care for either one. And that's simply a choice. They can work if used properly.
I like Microbe Lift BMC.....This is active BT spores that you only put like 8-10 drops in your feed. Now simply water to get the whole pot wet. Repeat this once every 5 days 4 times. Fungus gnat life cycle is broken....

I think sometimes when they come back. It's because folks have done the "dry" it out thing and the gnats have gone down deeper between the pot and the soil - That has pulled away from the pot due to shrinkage from lack of moisture. - and are laying eggs there. Possible anyway.

Now the thing is, If you treat with something in any liquid by watering. You must treat at least 3 times at 5 day intervals...You can not be sure you've killed them all with ANY single treatment....

Now then, When we can post pics again..I want to see those chewed leaves ok? Then we can get to that problem.
Personally, I might hit them with Cpt Jacks spinosad a cpl of times and see if the biting bugs go away, while you tame the gnats..

Cpt Jack's is OMRI


Good luck and leave the Neem for V's lunch spread.

Unless your running hydroponics or similar the gnat larvae will not be able to penetrate the grow medium. They can get into the top layer but anything saturated cuts off their air supply.

Really gnats are too common.

Dr. Who said:

This whole thread is entertaining as hell. First off, his problem is something eating new growth and close to it, leaves...correct? Like it has been said. It ain't fungus gnats!

You can get fungus gnats with hydro! They work the hydroton zone well. Same for rockwool and soilless.
I'll bet they came in by way of eggs in Budley's soil, when he did soil growing. Fox Farm soils have been known for this for about ever!

Everybody and their brother has a way to control or kill off fungus gnats...First thing is proper identification of the pest. I always have yellow and blue stickies out! If I find a bug stuck to it. I look at the sucker through a 60-100x scope and be sure what I'm about to fight is what it is!

Letting it dry out is always a place to start. Yet, gnats seem to give folks problems.

First off, calm down. Fungus gnats do little damage at all. They are more of a "pest" to you, then your plant. Unless of course you ignore them and they go ape shit all through your garden....

Many who say that "this or that" didn't work for me....Simply did not treat in a way to actually "break" the cycle....
Dunks and popular.
D. E. is too.
I don't care for either one. And that's simply a choice. They can work if used properly.
I like Microbe Lift BMC.....This is active BT spores that you only put like 8-10 drops in your feed. Now simply water to get the whole pot wet. Repeat this once every 5 days 4 times. Fungus gnat life cycle is broken....

I think sometimes when they come back. It's because folks have done the "dry" it out thing and the gnats have gone down deeper between the pot and the soil - That has pulled away from the pot due to shrinkage from lack of moisture. - and are laying eggs there. Possible anyway.

Now the thing is, If you treat with something in any liquid by watering. You must treat at least 3 times at 5 day intervals...You can not be sure you've killed them all with ANY single treatment....

Now then, When we can post pics again..I want to see those chewed leaves ok? Then we can get to that problem.
Personally, I might hit them with Cpt Jacks spinosad a cpl of times and see if the biting bugs go away, while you tame the gnats..

Cpt Jack's is OMRI


Good luck and leave the Neem for V's lunch spread.

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OP picked the wrong Ddos attack to post pictures after....

guy6969 said:

my plants are a little over a month old and are getting chomped by fungus gnats. I have recently tried spraying with soapy water and coating soil with cinnamon. Still have these buggers flying around. I see a lot saying to water with hydrogen peroxide water mixture but I have also read that will wipe out all microbes in my organic grow. Want to hear some opinions on that and if there are some other ideas I should try to get rid of these things quick I also put a apple cider vinegar w soap trap but none of them are getting caught. They are chomping on leaves bad and I know I need to figure this out quick

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GnatKnix. Put a 2 inch layer on top of every pot and you'll never have gnats again.

You definitely need the yellow stickies though. They get almost solidly covered with them.

Dr. Who said:

This whole thread is entertaining as hell. First off, his problem is something eating new growth and close to it, leaves...correct? Like it has been said. It ain't fungus gnats!

You can get fungus gnats with hydro! They work the hydroton zone well. Same for rockwool and soilless.
I'll bet they came in by way of eggs in Budley's soil, when he did soil growing. Fox Farm soils have been known for this for about ever!

Everybody and their brother has a way to control or kill off fungus gnats...First thing is proper identification of the pest. I always have yellow and blue stickies out! If I find a bug stuck to it. I look at the sucker through a 60-100x scope and be sure what I'm about to fight is what it is!

Letting it dry out is always a place to start. Yet, gnats seem to give folks problems.

First off, calm down. Fungus gnats do little damage at all. They are more of a "pest" to you, then your plant. Unless of course you ignore them and they go ape shit all through your garden....

Many who say that "this or that" didn't work for me....Simply did not treat in a way to actually "break" the cycle....
Dunks and popular.
D. E. is too.
I don't care for either one. And that's simply a choice. They can work if used properly.
I like Microbe Lift BMC.....This is active BT spores that you only put like 8-10 drops in your feed. Now simply water to get the whole pot wet. Repeat this once every 5 days 4 times. Fungus gnat life cycle is broken....

I think sometimes when they come back. It's because folks have done the "dry" it out thing and the gnats have gone down deeper between the pot and the soil - That has pulled away from the pot due to shrinkage from lack of moisture. - and are laying eggs there. Possible anyway.

Now the thing is, If you treat with something in any liquid by watering. You must treat at least 3 times at 5 day intervals...You can not be sure you've killed them all with ANY single treatment....

Now then, When we can post pics again..I want to see those chewed leaves ok? Then we can get to that problem.
Personally, I might hit them with Cpt Jacks spinosad a cpl of times and see if the biting bugs go away, while you tame the gnats..

Cpt Jack's is OMRI


Good luck and leave the Neem for V's lunch spread.

Click to expand...

Haven't had them yet in my hydro setup but not saying it can't happen just not yet lol. And as Doc says they didn't cause any damage to the plant that I could see and at one point I had a major infestation, watering the pot would have them swarming out and driving me nuts. I would hazard to guess that getting them in hydro is a lot less frequent, I'm the poster child for not taking many precautions .

Budley Doright said:

Haven't had them yet in my hydro setup but not saying it can't happen just not yet lol. And as Doc says they didn't cause any damage to the plant that I could see and at one point I had a major infestation, watering the pot would have them swarming out and driving me nuts. I would hazard to guess that getting them in hydro is a lot less frequent, I'm the poster child for not taking many precautions .

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Yup! Not often..I got them years ago when running ebb and soil in the same room. they came from the soil....Good ole Microbe lift in the res cleared that up (along with a cpl of pour through's on the hydroton.

Get some mosquito dunks

guy6969 said:

my plants are a little over a month old and are getting chomped by fungus gnats. I have recently tried spraying with soapy water and coating soil with cinnamon. Still have these buggers flying around. I see a lot saying to water with hydrogen peroxide water mixture but I have also read that will wipe out all microbes in my organic grow. Want to hear some opinions on that and if there are some other ideas I should try to get rid of these things quick I also put a apple cider vinegar w soap trap but none of them are getting caught. They are chomping on leaves bad and I know I need to figure this out quick

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Don't "let the soil dry out".. it makes the problem worse. You end up further damaging your roots making it more susceptible... Also, a layer of sand/perlite/glass/whatever on top is not effective because they will just move to the drainage holes. To do that you have to sit the pot in a dish and fill with the sand.. to also cover drainage holes. I've done that, it is messy, and not nearly as effective as other methods, honestly. Also, it makes watering a pita and can lead to more rotting, which leads to more gnats. Nematodes looked very promising to me at one time.. and they can be.. I do not recommend them in this situation though.

Here is what you do...

Go get Mosquito Bits.. get the 30oz jar. Take 1 cup of the bits and soak them about 2 gallons of water. Let soak for 24 hours. Stir the water up very well. Water all of your plants with it.. repeat every 7 days. 3 treatments. If you are large scale then look into gnatrol instead.

Also, lay out yellow sticky traps.. all around the plants.. when they have about 50 gnats on them, replace. They are more attractive to the gnats when they are cleaner.

Gnatrol can also be used instead of the Mosquito Bits Tea.. but I found that the Bits Tea is muchMORE effective than gnatrol. Mosquito Bits themselves in the soil is not very effective. The tea is VERY effective.

Trust me man... use the Mosquito Bits Tea. It will get the larva bettter than any of the other suggestions posted here. I promise.

If you are willing to stray from the organic thing.. Set off a Bug Bomb one day after you apply the bits.. Make sure you get one that only has Piperonyl Butoxide and Pyrethrins.. NOT cypermethrin.. NOT bifenthrin.. or anything else.. Just PB and Pyrethrins.. those are safe for flower. This is a very low toxic solution. Pyrethrin breaks down to harmless substance. And the PB just makes the Pyrethrin stronger.. not a toxin itself. It is very safe.. Just make sure you use them no less than 3 days out from harvest. That is more than enough time..

If you use the Mosquito Bits Tea, Yellow Traps, AND the Bug Bombs.. I garuntee your problem will go away. That said.. even just the Tea and Yellow traps is very effective. Most important is the bit tea.. ULTRA effective against larva.

Make sure to do at least one treatment after you see no pests at all.. 2 is better.. deal a final blow.

Sorry for the running on.. I can't just give simple answers.. I'm crazy.
Everything here comes from experience.. not stuff I just read.. I am able to try a lot of things as I care for all kinds of plants (not MJ) for a living, on someone elses dime.

Gnats require persistence. Read up on IPM. Apply IPM to every pest problem and you will be able to handle every pest problem.

ime, fungus gnats live THROUGHOUT the ENTIRE medium of coco, center, edges, top inches, bottom inches, the whole shebang. They mercilessly eat the rhizo fuzz leaving smooth noodles of roots.

SF nematodes works great for the gnats in my area, two days and the white worms will go dark brown and black as the todes eat the from the inside out.

The small white movers and the white worms I found throughout all my medium, not simply limited to the top few inches as I hear so often.

No combination of BTi, vinegar milk or coffee dishes, tanglefoot traps, gnatnix, and a variety of sprays would fully eradicate. Only after applying the SF nematodes that I noticed the critters in the medium started dying away.

Budley Doright said:

What do you guys put at the bottom of the pot to stop them there? I had them coming out the drain holes as well. I would let the top dry but that did nothing for the bottom. I tried dimascus earth but nope lol.

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Your pots should be drying more evenly then that. If the bottoms always wet you might have them in to large a pot.

goldberg71b said:

Your pots should be drying more evenly then that. If the bottoms always wet you might have them in to large a pot.

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Possibly and yup my soul does dry from the top down. I was just curious and will never find out as my indoor soil grows are over, never going back as I try to maximize my indoor to get as much possible per KWH used, it's fucking outrageous here for electricity

Haven't really been able to find the mosquito bits here since it is winter but I can look around more.. but still wish I could upload a picture because it seems that something else is eating away at my leaves. Can't really find much on what could be doing that anywhere