a guide to COCO and Fungus Gnats (little black flies)

Weezard · Dec 7, 2018

Dryer sheet on the air intake is good. But using fresh dryer sheets as a soil cover eliminates F.G.s completely. They used to drive me mad. Covered my soil surfaces and put some BT in my rain barrels.

Got my sticky traps out but have not caught any F.G.s for 4 years now They are repelled by the surfactants in the sheets not by the perfume, so get the unscented.
The barrier also breaks the lifecycles of thrips and root aphids.
Try it. They'rew cheap. You will be pleased.
Sadly, they do nothing for mites.

I have meat eating ants that patrol my plants to handle them buggahs.

Aloha,
Weeze

airdog420 · Dec 15, 2018

I use Og biowar in my Repertoire. Plants love it bugs don't..

soil margin · Dec 16, 2018

Dryer sheets are nasty stuff frankly. Not a horrible idea but really poorly executed. Really don't want those types of chemicals anywhere near the bud that I'm going to be smoking and/or eating. A thick layer of sand as mulch should do the trick equally well without leaving any unhealthy residue.

BongFu · Dec 30, 2018

bucketgirl said:
Not sure if someone already posted this link to the relevant manic botanix article:

https://web.archive.org/web/20160602114456/https://manicbotanix.com/fungus-gnats-in-coco-coir/

(I posted the wayback machine cache since this site seems to be down often)

TLDR: The article found best results with Spinosad over Gnatrol, but doesn't elabortate on the reasoning for the ineffectiveness of bti in trials. I like this info though because though there is some amount of exception and room for opinion, it's unusally well-sourced compared to the anecedotal evidence and wives-tales suggested elsewhere.

I have followed this article and have been trying Spinosad with some success but it can't prevent them from coming back. I mix Montery at 55ml/g and apply once during dark cycle (I don't bother rinsing it out, just continue with normal feeding after), then again in 5-7days later, the idea being to kill larvae then kill any more larvae from the fliers that were left. I use yellow sticky sheets to monitor FG levels to measure effectiveness. I also filter my intake air ducting ith dryer sheets.

God I hate those little black fuckers.

Anyone else experimented with Spinosad?

This is one of my favourite grow sites. I haven't really ever noticed it down when I have visited. The person (people?) behind it has a new site up where all the material can be found (the manic botanix site forwards to it). Like you said the content is well sourced and heavily referenced to academic papers so its science vs pseudo science and questionable "old wives tales"

Spinosad works really well but I found doubling the dose recommended to about 150 ppm works even better. Completely knocks them out. Just one drenching during the crop cycle. And there is academic references they link to re spinosad being really efficient for killing gnat larvae.. Link to the online article is here https://medteknutrients.com.au/fungus-gnats-in-coco-coir/

Mikell · Dec 30, 2018

soil margin said:
Dryer sheets are nasty stuff frankly. Not a horrible idea but really poorly executed. Really don't want those types of chemicals anywhere near the bud that I'm going to be smoking and/or eating. A thick layer of sand as mulch should do the trick equally well without leaving any unhealthy residue.

Mmm he suggested the unscented and surfactants are common enough.

Is there a particular chemical residue you're concerned about? Uptake by a plant typically needs to be engineered or worked towards.

bucketgirl · Jan 4, 2019

@Weezard

I must say that I question the dryer sheets on top and it will be a bit of a pain to secure them down with the fans blowing them all over, but it'd be bogus to slam it before I try it. I'll give it a whirl...I'll try putting a loose layer over my drip rings next cycle. I'll leave some off and compare. Thanks for the advice!

As for the negative "chemical-y" nature of the dryer sheets, I can't comment intelligently. While I'm experimenting, I'll use the tamest, most unscented sheets I can find and won't be letting my nutrient solution pass through them on the way to the coco. That's good enough for me...I doubt there's any harm. If I'm wrong, bon voyage!

@Bongfu

Good call, I will try the extra spinosad blast as well and see how that fares. Thanks for the tip, glad we enjoy the same late night reading material. Short of reinventing the wheel, you gotta trust somebody. Confirming that the author of what you're reading has a fully functioning brain seems like a good first step. Always more to learn!

Weezard · Jan 5, 2019

soil margin said:
Dryer sheets are nasty stuff frankly. Not a horrible idea but really poorly executed. Really don't want those types of chemicals anywhere near the bud that I'm going to be smoking and/or eating. A thick layer of sand as mulch should do the trick equally well without leaving any unhealthy residue.

You may want to research that.

The surfactant is a wax that sublimes when heated. It does so quite slowly at room temperatures and these waxes are non toxic.

In fact there are crazies that eat a box of sheets a day with no apparent harm.

(And no internal "static cling" either.)

I can taste Spinosad and will not spray it on my plants.

But I will add that, and/or B.T. to my irrigation water.

At least I did 5 years ago.

Now, I need nothing but the dryer sheets, outdoors, in the tropics.

Aloha,
Weeze

BongFu · Jan 5, 2019

Weezard said:
You may want to research that.

The surfactant is a wax that sublimes when heated. It does so quite slowly at room temperatures and these waxes are non toxic.

In fact there are crazies that eat a box of sheets a day with no apparent harm.

(And no internal "static cling" either.)

I can taste Spinosad and will not spray it on my plants.

But I will add that, and/or B.T. to my irrigation water.

At least I did 5 years ago.

Now, I need nothing but the dryer sheets, outdoors, in the tropics.

Aloha,
Weeze

Spinosad should be used as a drench and not sprayed. If you kill the larvae you wipe out the lifecycle. Adults flying around after a drenching aren't an issue and adults do zero damage to plants other than lay hundreds of eggs which become root eating larvae. Spinosad in organic substrates such as coco peat isn't uptaken at all by the plant so there can be no Spinosad "taste".

BongFu · Jan 5, 2019

bucketgirl said:
@Weezard

I must say that I question the dryer sheets on top and it will be a bit of a pain to secure them down with the fans blowing them all over, but it'd be bogus to slam it before I try it. I'll give it a whirl...I'll try putting a loose layer over my drip rings next cycle. I'll leave some off and compare. Thanks for the advice!

As for the negative "chemical-y" nature of the dryer sheets, I can't comment intelligently. While I'm experimenting, I'll use the tamest, most unscented sheets I can find and won't be letting my nutrient solution pass through them on the way to the coco. That's good enough for me...I doubt there's any harm. If I'm wrong, bon voyage!

@Bongfu

Good call, I will try the extra spinosad blast as well and see how that fares. Thanks for the tip, glad we enjoy the same late night reading material. Short of reinventing the wheel, you gotta trust somebody. Confirming that the author of what you're reading has a fully functioning brain seems like a good first step. Always more to learn!

Some good information on Bounce dryer sheets and fungus gnats @ https://gpnmag.com/article/repelling-fungus-gnats-dryer-sheets/

Actives are All varieties of Bounce Dryer Sheets include the following ingredients: Dipalmethyl Hydroxyethylammoinum Methosulfate, a Fatty Acid, a Polyester Substrate and Clay, according to the product safety information provided by the manufacturer. Many varieties also contain fragrances, which give the products scent

There is no known toxicity issues with Dipalmethyl Hydroxyethylammoinum Methosulfate although I have to say as soon as I hear methyl the alarm bells ring. Still if they are on top of the substrate and not being irrigated over (i.e. Dipalmethyl Hydroxyethylammoinum Methosulfate is not finding its way into the root zone) why would any issue exist???

aridbud · Jan 5, 2019

Those fungus gnats are maddening....I''ll use 30% coco coir in organic soil and use a higher quality coco. Just like 'organic soil' ....some are better than others. Do your research!

Hyponex is the WORST as far as potting mix.....hard to get rid of those pesky gnats. Grrr!

BongFu · Jan 6, 2019

aridbud said:
Those fungus gnats are maddening....I''ll use 30% coco coir in organic soil and use a higher quality coco. Just like 'organic soil' ....some are better than others. Do your research!

Hyponex is the WORST as far as potting mix.....hard to get rid of those pesky gnats. Grrr!

Yep they are a given but truthfully they don't worry me at all now. Good drenching with spinosad once during the crop cycle and they are under control. A few gnats isn't a problem but when their numbers go nuts they are a big big problem for a small pest. I also vent my inlet air but in reality I think they often come in with the media.

Mikell · Jan 6, 2019

BongFu said:
Spinosad should be used as a drench and not sprayed. If you kill the larvae you wipe out the lifecycle. Adults flying around after a drenching aren't an issue and adults do zero damage to plants other than lay hundreds of eggs which become root eating larvae. Spinosad in organic substrates such as coco peat isn't uptaken at all by the plant so there can be no Spinosad "taste".

https://www.ncbi.nlm.nih.gov/m/pubmed/16180075/

BongFu · Jan 6, 2019

Mikell said:
https://www.ncbi.nlm.nih.gov/m/pubmed/16180075/

Different substrates with varying percentage of clay and organic matter were tested in comparison with rockwool and showed that sufficient control was restricted to the rockwool substrate.

Its got to do something with spinosad being less available for plant uptake in organic substrates.

BongFu · Jan 6, 2019

Spinosad has high efficacy, a broad insect pest spectrum, low mammalian toxicity, and a good environmental profile, a unique feature of the insecticide compared to others currently used for the protection of grain products.[5] It is regarded as natural product-based, and approved for use in organic agriculture by numerous national and international certifications.[8]

Mikell · Jan 7, 2019

BongFu said:
Different substrates with varying percentage of clay and organic matter were tested in comparison with rockwool and showed that sufficient control was restricted to the rockwool substrate.

Its got to do something with spinosad being less available for plant uptake in organic substrates.

Right you are. I remembered that one wrong and did not reread before posting.

BongFu · Jan 7, 2019

Mikell said:
Right you are. I remembered that one wrong and did not reread before posting.

I think also that even in rockwool the mg/kg of spinosad is extremely low and I strongly suspect you wouldn't "taste" it. Spinsoad itself is extremely low toxicity to people which is one of the reasons I like it as an option. It's organic so it must be good right? Lol

Mikell · Jan 7, 2019

No I don't think so either' despite the God awful smell of the stuff. Only had thrips omce and it did the job in one go. I can't imagine the odour has improved sitting on the shelf for four years.

BongFu · Jan 8, 2019

Mikell said:
No I don't think so either' despite the God awful smell of the stuff. Only had thrips omce and it did the job in one go. I can't imagine the odour has improved sitting on the shelf for four years.

Lol nope I expect not. It sounds like bacterial metabolites. I bought a kg of the stuff from China a ways back and it has no odour at all as powder @ 98% purity. Pain in the ass to make water soluble though so I expect it is what they use to make it soluble for shelf sales that caused the odour.

woolybear · Jan 9, 2019

I've had fungus gnats / winged root aphids (forget which) and the only thing that has kept them out is BTI.

Got my BTI off of ebay. When them bugs get to working they cause leaf damage, the #1 symptom.

Treetroit City · Jan 9, 2019

woolybear said:
I've had fungus gnats / winged root aphids (forget which) and the only thing that has kept them out is BTI.

Got my BTI off of ebay. When them bugs get to working they cause leaf damage, the #1 symptom.

Must not be fungus gnats then cause they do no damage to leaves at all. They get stuck on my leaves but no damage.

a guide to COCO and Fungus Gnats (little black flies)

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