Recycling Fungus Gnats?

[gOurd^jr.]

Like the Title says, I am using recycled soil, current flowering is finishing its second run with the soil. Some premium bagged soil was used as a base and combined with bulk compost, lots of wormcast, char, kelp, azomite, rock dust, and more goodies as well. plants loved it, but so do the fungus gnats.The gnats have gotten away from me the last couple weeks and there are quite a few crawling/flying around the soil surface of about half the plants. What would you do to deal with the gnats while still reusing this soil? I don't think I can bring myself to chuck it and make new soil, I'm talking about around a yard of dirt here. I did neem the soil surface when I first noticed the gnats and also later used some clove/rosemary oil(SNS 203). It helped for a little while but, by the time I discovered the gnat larvae are abundant on the BOTTOM of the pots(where it stays moistest) it was so close to harvest I decided to just ride it out and I spent time daily hunting down all the flyers I could find in lieu of drenching anything.
So now I am harvesting the room and have to deal with these gnats as I look to recycle the dirt once again. What would you do? I will be using an ozone generator in the room as per usual between harvest cleaning routine. I thought about leaving the soil in while ozone the room but I feel like it would take a loong time for the ozone to penetrate deep into the soil and get the gnats/larvae as I'm sure they would retreat to the interior of the pots (felt pots btw). Of course I'm not that into sterilizing my soil either after all the work I've done to cultivate a rich living soil. Another option I'm considering is to drench the soil with neem once the plants are out. like 2-3 times over the course of a week or so. In my veg the neem drench seems to have taken care of the gnats nicely, so I think this is a good option. maybe I'll ozone for a few hrs and kill whatever gnats it will, then neem drench...
MY other thought is about freezing, winter is fast approaching here and this dirt will certainly freeze deep before I finish the next upcoming flower cycle( using soil that has been sitting in an outdoor bin and amended) and need to use it again. will freezing kill the gnats? is that all I need? If you have any thoughts/suggestions I'd love to hear'em!
Thanks all!
<3
gOurd

 

[xmobotx]

I bet your neem drench plan would work/might be overkill / maybe 1x then a week later another

neem is fert too BTW

are you doing no-till or mixing your soil together between? If your mixing again, consider neem seed meal as an amendment.

 

[supermanlives]

i put mine in black trash bags and set in full sun. i fill bags only like half way and flatten them out in sun. no more gnats

 

[Rusty420]

so how exactly do you recycle these fungus knats...?? make them into tiny stuffed ornaments?? dress them up in little uniforms and re-enact ww2 battles?? turn them into bio-fuel???

 

[nomaad]

Hit the soil with Bacillus Thurigensis israeliansis. (Gnatrol, Mosquito dunks, Microbe Lift.) Its pretty common for bagged soil to have some gnats in them up here in Norcal... Roots organic specifically,m but I have had gnats come in FFOF as well.

I have used BTi in every soil run I have ever done and used it with 100% effectiveness in my cloning opeartion a couple of times when overwatering bagged soil in the 3.5" pots led to a bad gnat problem.

Its organic.

Cooking your soil between runs is a good idea too. CLEAR bags in the sun are superior to black bags... use the search function to find articles on SOLARIZING soil. I once thought that black plastic was best for solarizing, but if you think about it. ... the point of the plastic is to keep heat and moisture in... black plastic blocks light while doing this. instead of the light hitting and heating the soil, its hits and heats the black plastic... the almost black color of the soil itself will collect the direct light/heat thru the clear bag.

I believe gnat larvae can survive up into the 125 degree range, so you might want to hedge your bets with a little very cheap BTi anyway.

good luck.

 

[supermanlives]

^^^^ thanks . will look for clear bags in future and test em myself.

 

[schwagg]

predatory nematodes could help. gotta love the little fuckers.

 

[gOurd^jr.]

Thanks for the input guys! BTi sounds pretty good...and neem seed meal is a great idea I should probably get some of that into my soil bins.
I pretty much just have a couple big bins in the yard that I dump the rootballs into and break up amend with lots of good stuff and turn it a few times while the other batch of soil is in the flower room, then I switch 'em. It gets tricky during the sorta lengthy cold winter here, but I should be able to get this harvests rootballs broken down and "cooked" for a couple weeks before it freezes solid. then after I harvest next in ~3months I'll just have to bust it out and thaw it inside. PITA but what ya gonna do? And the rootballs I harvest in ~3 months should be warmed up enough to breakdown roots and amend by march about when I'll be harvesting again. Chicken shit and dry molasses can heat things up pretty quick I've found! Char and loads of homemade castings are other big players and other goodies go in too for minerals and such. Some free aged manure in there sometimes. I kinda keep one mixed to veg and the other a bit stronger and more P for flowering. between the two I do have a bit of extra soil in the rotation but I doubt it's a whole cycle's worth, probably about half. started up the action about a year ago...

 

[Yes4Prop215]

anyone tried SNS 203? its mostly rosemary oil......just got a free bottle from the hydro store doing some dunks on a few plants to see if they affect the plants negatively at all....then probably gonna dunk everything.

 

[gOurd^jr.]

I used a little bit of SN-203. It seemed to help, but as I stated in the OP I was just spraying it on the top of the soil, and hitting some of the flying gnats in the process. However I later discovered there were lots of larvae living on the bottom of the pots. I discovered this on my small veg plants, not the big flowering pots. I opted to just ride it out the last couple weeks in flower and use neem concentrate in veg...

 

[mad librettist]

well this is not a complete thread unless I bring up a living mulch...

fact is, what makes gnats dangerous is monoculture, especially at the seedling stage. Your seedling is the only thing to eat, so it gets eaten.

However, if your seedling is just one plant among hundreds, your chances of survival shoot way up.

Also, if your containers are fully colonized by roots, gnats have a hard time making a living. Living mulches allow your young plants to grow in a container already fully colonized (don't worry, the roots coëxist well together if you pick the right species)

The other nuisance with gnats is they love to hang out in rotting flowers (caused by mold). Then they carry around spores and deposit them on other buds.

 

[nogoodname]

Cooking your soil is one way, but I think it will kill many beneficials as well. You did work hard to colonize...I have dealt with a pretty bad infestation of fungus gnats as well. I would recommend the granulated mosquito dunks[BTi] to the tune of 1 teaspoon per gallon of soil mix. Blending well and keeping your soil moist during your recycling period should give the BTi lenty of head start. You may consider always using dunks in your water aging/ holding tank. Lastly, a physical barrier will also help stop them from invading your soil in the first place. Extra large womens stockings/nylons are very cheap and will slip over most pots. You just tie it off around the stalk and no access for egg laying. Hope that helps! Good Luck!

 

[BOMBAYCAT]

I've had good luck with Mosquito dunks. You get them at any big box store like Lowes or Home Depot. I crunch up about 1/4 TSP and put it in the plant water. I also put a few grains in the little trays under the plant's pots to catch runoff. It's not instant but in a couple weeks no more gnats. Also spiders love the fresh food so I let the spiders feast for a while.

 

[gOurd^jr.]

Well I will let you all know how it goes this round with the gnats. They made their way into my veg tent, though I've kept them from going nuts. I neem drenched everything a couple times about 4-5 days apart several weeks ago. Then about a week and a half ago I applied predator nematodes. Still occasional gnats and some larvae visible on the bottom of the pots, but not nearly as many as on the last round of flowering plants. I just transplanted the veg plants up into their final homes of 7/10 gal smart pots. I mixed some BTi (mosquito bits) into the bottom couple inches of the soil and the top couple inches as well. I'm watering with blumats and I think I'll go ahead and sprinkle some bits in the water tank while I'm at it. These things really annoyed me last round...
Oh and Mad I'll be trying a living mulch this round too, just posted in that thread...
Cheers all

 

[headseed]

How about diatemaceous earth for gnats?

 

[gOurd^jr.]

it did nothing. I sprinkled a good amount over the surface of the soil and it had no noticable effect on the gnats. MAYBE on the bottom where I found lots of larvae it could dessicate them though...I also later applied a half inch or so of sand over the surface of the soil and that seemed to slow the gnats down for a few days, but shortly they were back in full force.

 

[SeaMaiden]

They're not causing problems, are they? If so, those may not be fungus gnats. Either way, continuously using only one treatment leaves the way wide open for resistance--rotate controls.

If it were me I would let the soil 'rest' between grows or cycles. I would have different batches with which to rotate.

 

[gOurd^jr.]

No, they aren't causing real trouble, just annoyance, and sticking to buds like flypaper...
The larvae are dead on for Fungus gnats from the sticky thread in infirmary, viewed at 40x though they are easily visible to the naked eye.
I do wish I was running a no-till no rest grow, but I do have two+ batches of soil and each one is reamended and "rested/cooked" outside in a pair of big bins while the other is in the flower room. see post #8.
I have certainly been rotating controls as well.
thanks for the input, I'm curious why you'd favor resting soil in between cycles, since the consensus around here (and the permaculture farm world) that no-till, no-rest is where it's at. I like this way cause I can bring in larger vegged plants, pot them into their final home of fresh soil and quickly have the room full of sizeable flowering ladies again.

 

[SeaMaiden]

I think it could help disrupt the life cycle. Sorry for missing about the rotation, I'm on a new machine, completely new technology to me.
If they're no more than an annoyance, then how about just sticking with sticky traps for control?

 

[gOurd^jr.]

Sticky traps don't provide much control from what I experienced. They do catch some gnats, and I had enough in there that the traps actually caught a lot, but I'd say <10%, most of the gnats seem to stay around the soil surface and just don't land on the traps. plus I have seen gnats land on the traps and still get off them sometimes. I'll keep some taps, but would not count on them as a real effective control.
The predator nematodes seemed to help significantly, though still had larvae and flyers after 2 weeks, much less numbers though.
Since transplant into final pots with BTi mosquito bits mixed into the bottom and top couple inches of each pot I have not really seen any gnats around. only been a week though and transplant seems to slow'em down for at least a couple days as everything gets buried into the middle of a bigger pot of dirt...