Fungus gnats in DWC

Hey. Ive recently discovered I have fungus gnats terrorizing my 3 plants. 1 plant moreso then the others.

I've gone down to my local nursery and purchased some sticky yellow strips to grab the flying adults. I've also bought myself a small bottle of neem oil.



I wanted some mosquito dunks to soak the res with but couldn't seem to find them short notice. Whats everyone think about dropping some neem oil into each plants res to kill the larvae?

Shag Pile said:

Hey. Ive recently discovered I have fungus gnats terrorizing my 3 plants. 1 plant moreso then the others.

I've gone down to my local nursery and purchased some sticky yellow strips to grab the flying adults. I've also bought myself a small bottle of neem oil.

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I wanted some mosquito dunks to soak the res with but couldn't seem to find them short notice. Whats everyone think about dropping some neem oil into each plants res to kill the larvae?

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I don't know that it would be effective.

Predatory nematodes - bad ass little things that will put the hurt on the larva -

FennarioMike said:

I don't know that it would be effective.

Predatory nematodes - bad ass little things that will put the hurt on the larva -

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They look like a great idea. Alot of the info im reading says add them to a watering can and water into soil. As im in dwc, are they able to be added straight a res?

Yes they can - but what are they feeding on? Usually it's damp soil or coco that grows fungus that the gnats feed on. Usually with DWC there's nothing damp on the surface tat they can feed on.

They can burrow into roots and cause big shit.

ANC said:

They can burrow into roots and cause big shit.

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Yes they can - but usually in DWC they have to get through a dry layer of hydroton to get to it, so they don't. I'm wondering if there's something on the surface that's attracting them to begin with.

Well they're definitely feeding on the roots on one plant. It was germinated in a peat pellet. Once a seedling, I placed the peat pellet in a 80mm net pot and fillled the rest with hydroton.

I beleive I have been filling the bucket too high and soaking the the peat pellets. On the bucket in question the pellet was exposed at the surface which is probably why they've got down to the roots.

The plants are close to harvest and will make it. But Ive learnt something to do differently next run. Thanks everyone!

ANC said:

They can burrow into roots and cause big shit.

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Your referring to the gnats feeding on roots right. Not the nematodes

Yeah, that's one of the most common causes of issues in DWC is using any sort of absorbent rooting material - if it can't drain adequately. They can hold onto too much water causing decreased O2 in that space and overwatering symptoms as well as harboring pathogens. I've had them cause damping off at the stem and lost a couple to that before I switched to roots only. Now, I use the peat pellets to sprout clones, but as soon as the roots start poking out, I carefully peel back the netting on the peat and rinse all of the peat off. Then I pop that in a DIY bubble bucket (with just tap water) with a neoprene ring for another week or so. Then I transplant when it has a good long root that I can drape through the holes in the netpot and backfill with hydroton. No muss, no fuss.

I think that maybe you should go with mosquito dunks. It might be a bit more effective in DWC than nematodes. Definitely don't use them together - the dunks will kill the nematodes.

Next batch I highly recommend ditching any rooting plugs in the netpot.

Yeh man! I seen a post from you about cloning in peat pellets and then removing the netting and moving to the net pot. I actually screenshot it for future reference. Great idea, rules out a few possible problems. I'll definitely be doing it next run

Shag Pile said:

Yeh man! I seen a post from you about cloning in peat pellets and then removing the netting and moving to the net pot. I actually screenshot it for future reference. Great idea, rules out a few possible problems. I'll definitely be doing it next run

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Yeah, I think it really prevents a lot of problems and you also don't have to wait for a week for roots to show through the netpot.

How do start from seed and remove the jiffy pellet? The stem really wouldnt be strong enough to much around with it like that.

Also mosquito dunks arnt in australia. I believe the active ingredient (bacillus thuringiensis israelensis) is banned. Thats why I ended up with neem oil and sticky traps.

damn bt was my suggestion, good luck man bt is the best for dwc you'll have to do the whole bit then, traps and prevention will be your best tools