Google says..H2O2 kills fungus gnats/thrips larvae

[little-soldier]

Thx man. Winters are harsh around here so Ill probably buy my soil in the winter and let it freeze for a couple days outside before i bring it back inside and put them in plastic garbage bags so they are air tight. Cheapest way. Thanks y'all.

 

[Dropped Cat]

Freezing may not destroy the eggs, as many insects have evolved
to accommodate the deep freeze.

No insect has evolved the capacity to survive boiling temps.

 

[webwiller]

Ladies & Gnats: Start your engines!!!

Ladies & Gnats: Start your engines!!!

Interesting 3d...

I just faced this issue and researched a bit. H2O2 does work, but as some of you said, it kills all larvae & bacillus, good & bad.

Therefore if you spent a fortune inoculating your soil with nematodes SF, thurgensis family as BTI, BTK, BTA & whatever you wanted to, well, it could be really costly.

I like the BTI as they will act as food and when the larvae eat them, they release an enzyme that inhibits the host protective gut layer and they die by sepsis. Then the BTI lays his eggs in the cadaver to prepare a good meal for newcomers, pretty cynical, innit?! A good example of how life goes! Sorry for the OT...

I found a big chemical distributor and got 1L (1/4gal) of H2O2 @15% for 13$ give or take. This way you have a much easier life diluting the solution, this way you make 16gal (25L) with just 1L (1/4g) of peroxide.

To be safe and not sorry, I repeated the administration 4 times every other day, in case any egg survived or adults laid new eggs just after application.

Remember that eggs get laid and larvae live/stay on the first couple of inches of soil only. They never go much deeper. Said that you can spray the soil making sure you don't leave any spots untreated, but don't need to soak your plants. Unless you have a 4m./13f high Sativa (and smashed the ceiling to fit it in XD) with 2L/half gal p/p you'd be fine, times 4 applications you'd need 8L/2g in total.

Simultaneously I used sticky traps for the adults, and I cut them and spread them evenly everywhere between the canopy and close to the soil.

A 1" (2.5cm) layer of perlite evenly spread on top of the pots will also work as a barrier for the Pupae to exit and they'll die (this trick can also save your ass if you forget watering!)

Otherwise, you could go BIO and attack them with Nematodes SF (in huge number) and a couple of millions BacillusThurigensis israelensis (BTI) (Mosquito Bits!). Bio, cheap, easy, safe and works.

Talking about sterilization techniques I'd add the UVA. Serious soil producers sterilize with UVA Lamps.

The sun is truly effective tough!('n for FREE!!!) If you spread the soil on top of a plastic bottom film and you cover it with one more layer f plastic above, in 48/72hrs soil will be sterile. I'm not sure this would work in each & every case. I mean, if you are close to the equator and have the sun right on top of you and it's summertime and you have 2 fantastic sunny days with 90°F, well, I doubt something can live 48hrs in there...with over 140°F constant for 15hrs daily minimum+ high UVA radiation. If it's April and you're in Anchorage well...it might work, cause of the UVA effect (which would be much much less anyway, is not a matter of temperature only. Maybe it'd take 3-5 sunny days but still...).

This is all I learned (minus what I forgot, LOL).
Ciao ALL!

 

[puggle6]

For people reference,

I used OxyPlus (50% h2o2) at recommend dose (2ml per 10lt) to knock down gnats and more importantly Pythium

It's worked well and not seeing Pythium issues in seedling but didn't fully get rid of the gnats.

I have a pot with a male in it so thought I'd see how much a plant can take.

I drenched with 10x recommend dose without any adverse effects to the plant


Ymmv

 

[spazspaz]

There are other hydrogen peroxide threads on icmag to look at, with discussion of ratios and bacteria relationships.

I started experimenting with H2O2 added to soil feedings much later than I should have. It’s still a constant maintenance project—but bang for buck, it might be the best thing I’ve tried. Promising.

Sure gnats, et al. can come in with new soil, but even if you ran a pallet or two of soil through a rice cooker in your spare time, it’s no guarantee gnats won’t seek out your scene pretty soon after. I like the idea of the tarp sandwich bake idea, but I have my doubts. I’d be afraid of starting a gnat farm and ant colony.

I’m no longer enthusiastic about BTI, including $400 5 gal buckets of gnatrol. Azamax (post talstar controversy) soil drench is an extremely expensive way to get a little peace—there’s a nuclear apocalypse vibe, where you can just sense you won the war...for about a week. And deathcorp gets richer.

I used to get gnats sometimes doing hydro flood and drain tables with clay pellets in baskets, too.