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BLhaze

Little black flies in soil (gnats?) advice needed.

21 posts in this topic

Hello community, i kinda feel stupid for asking as im sure this is probably a very common problem but im unsure what my options are, iv noticed a couple of my outdoor, greenhouse pots have little black flies in them (im guessing gnats from a little research). Are they damaging? If so how bad? The ones noticed them in most are around 1 week into flowering (autos) can they be treated? Etc etc

 

much appreciate any advice guys! 

Edited by BLhaze

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I'm not an outdoor grower mate so I don't know what chemicals to use to get rid of them but I know if you can get ladybirds or their lava they will munch through them rapidly.....

 

 

good luck mate....

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Do you mean in compost? or in soil?

 

i get them in compost, normally let it dry right out, helps deal with them a bit, do not cause any problems with the plants as far as i can tell

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Fungas gnats do not leave when you dry the soil out. I harvested my plant, went away for 4 weeks, came back and guess what - they are still living in the same soil that hadn't been watered in a month. 

 

I heard that a fairly thick layer of sand will stop them being able to enter and exit their breeding ground. However I have used 'gnatnix' which works in a similar way to great success. 

 

edit: hazeworks is right, they don't actually do much damage, I think they actually play a vital role in breaking down organic material... it's just annoying to find a little dead fly in your bud! 

Edited by j2o
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I agree with j20, drying it out is not the thing to do as you will do the plamt more harm than good. The ghats will still be there maybe in lower numbers until watered and they breed again. I've had them with several grows now, i just put sicky fly traps around the soil and have also used sand in the past, even clay pebbles.

All the best.

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Cheers peeps, damage to the roots was my main concern but if they dont do much if any damage then i might try the ladybird option as well as trying to have the compost dry for longer.. 

 

Yeah its in compost not soil..

 

ill have a look into designated products if they get much worse :yep:

 

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Fungus gnats are sneaky fuckers but although they may seem harmless buzzing round once they get a few and start a breeding cycle your in for a fight.

 

They can certainly cause some damage as the grubs eat fine root matter so the quicker you get on top of it the better.

 

For a treatment free approach all you need is a hand vacuum in your hand when your in your tent and you can do a pretty good job if spend a week or two trying hard to annihilate the little gits!

 

Careful with the plants though as they don't like being sucked very much.

 

They like damp soil and especially any sitting water under pots.

 

If you want to really defend and protect then sitting your whole pot in a leg of "big girls tights" and tie around the base of your trunk will annoy them pretty well and because it's over the entire pot they can't contact soil at all but will still get into any wet corners.

 

Tights work well as they don't shut out the O2 only the bastard gnats.

 

They can also get sucked into your tent pretty easily so if nothing else use a fine filter over your intake,I fitted a cheap plastic ducting piece with (more) tights and fitted it into the relevant hole in my tent.

 

They also really hate strong air flow so turn that fan up if it has more to give.

Edited by Badbadger
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6 minutes ago, j2o said:

I heard that a fairly thick layer of sand will stop them being able to enter and exit their breeding ground.

 

that's true mate, or even gravel or something will help, as long as it covers the top of the pot it will stop them getting to the soil so easily.....

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Just to add that they've never seemed to cause any hassle to the plants and never noticed a drop in yield either compared to other grows. Also had springtails in the past, never an issue either.

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I did think about trapping them in and blocking them out, ie. Something on the top of the soil, sand, sawdust, and then covering ihe pots with cling film or something but tights sounds really good tbh.. Cling film is way to faffy for my fat fingers! Tights i can still get the wet stuff through them without taking them off... lollol 

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Much appreciated.. Ill way up my options n see whats going to be the best + simplest method... Definitely be going to a self serve checkout with my packs of tights!! 

 

 

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Just be careful when putting tights over intake holes because they restrict air quite badly. I wouldn't recommend it myself

 

You can also use spreader mat when you pot up to block the bottom holes

 

Sticky traps are a must and like already mentioned a hand held hoover works great. No need to do the canopy. Just shake the trunk at the bottom of the plant and you'll see them come out the medium and off the bottom of the plant. They are an idle gnat and mostly stay well under the canopy and don't fly much

 

 

Owd

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Neem oil-soil drench and foliar spray, that will sort the fuckers :skin_up:

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Tanlin works, it's the new name for nil nat. +1 for sticky traps also 

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1 hour ago, Owderb said:

Just be careful when putting tights over intake holes because they restrict air quite badly. I wouldn't recommend it myself

 

You can also use spreader mat when you pot up to block the bottom holes

 

Sticky traps are a must and like already mentioned a hand held hoover works great. No need to do the canopy. Just shake the trunk at the bottom of the plant and you'll see them come out the medium and off the bottom of the plant. They are an idle gnat and mostly stay well under the canopy and don't fly much

 

 

Owd

cheers bud, yeah i know about restricting air flow. The tights wiuld of heen to cover the pots.. The hoover cant be done where my spot is!  lol If they are quite dormant pest and are practicaly harmless unless severly infested i think i will just try contain it.. Sticky traps.. Sand or other materials etc 

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