Amnesia Posted August 16, 2009 Share Posted August 16, 2009 I've just noticed a few of those dreaded Fungus gnats on the top of my compost,its not a big problem yet as theres only a few but i want to eradicate them before it gets out of hand.After doing a bit of research on here i know the larvae are just under the soil and can eat/damage the fine roots but the adult flies don't do any real damage to your plants.So i was wondering what is the best plan of action i should take? Buy some "Gnat off" and just mix 1ml/ltr when i water them? (is it any good?) or Cover compost with washed Sharp sand or Perlite? I will be buying some yellow sticky traps from Q&B tomorrow anyway to keep the adult numbers down.I just need some advice as to which of the above options i should do. Thanks in advance! 1 Link to comment Share on other sites More sharing options...
Hughie Green Posted August 16, 2009 Share Posted August 16, 2009 Stcky traps and sand should do it Amnesia Link to comment Share on other sites More sharing options...
Arbuscule Posted August 16, 2009 Share Posted August 16, 2009 They've just appeared in my grow for the first time this week (week 8 flower) - wth c4 weeks to go I wonder if I should do something Just saw above about the little scamps nibbling the fine feeder roots don't want that Sorry to butt in on your thread man but I jumped when I read your post I was all - should I worry Little shites ain't having at my lovely Lot#5 Should I be concerned this late in the grow or just research it for next time ? Link to comment Share on other sites More sharing options...
Hughie Green Posted August 16, 2009 Share Posted August 16, 2009 As above Arbuscule mate, traps for the adults and sand to prevent the larvae emerging from the medium, if your quick enough you will break the life cycle get rid of the wee buggers Link to comment Share on other sites More sharing options...
Arbuscule Posted August 16, 2009 Share Posted August 16, 2009 Nice one Hughie Link to comment Share on other sites More sharing options...
Amnesia Posted August 16, 2009 Author Share Posted August 16, 2009 Thankyou Hughie,a lot cheaper too than £20 for Gnat off! I don't think they are really much of a problem to the plants or roots unless you have an infestation,So i would not worry about it Arbuscule as you only have just noticed them!.I would do the same as me though and treat the pests early. A half inch of sharp sand on top of the pots and some sticky yellow traps it is then! I've also just read on here that if you want to know how bad your infestation is just get a half of potatoe peeled and put it in the top of the soil,the larvae and flies will be drawn to it.Check underneath a few hours later and you'll see them there. 1 Link to comment Share on other sites More sharing options...
Arbuscule Posted August 16, 2009 Share Posted August 16, 2009 Thankyou Hughie,a lot cheaper too than £20 for Gnat off!I don't think they are really much of a problem to the plants or roots unless you have an infestation,So i would not worry about it Arbuscule as you only have just noticed them!.I would do the same as me though and treat the pests early. A half inch of sharp sand on top of the pots and some sticky yellow traps it is then! I've also just read on here that if you want to know how bad your infestation is just get a half of potatoe peeled and put it in the top of the soil,the larvae and flies will be drawn to it.Check underneath a few hours later and you'll see them there. Cheers Amnesia :wink: Reckon I'll get some sand - thanks Link to comment Share on other sites More sharing options...
BluePixie Posted August 16, 2009 Share Posted August 16, 2009 I've also just read on here that if you want to know how bad your infestation is just get a half of potatoe peeled and put it in the top of the soil,the larvae and flies will be drawn to it.Check underneath a few hours later and you'll see them there. Nice tip Amnesia........ Link to comment Share on other sites More sharing options...
highgrower Posted August 16, 2009 Share Posted August 16, 2009 I tried gnat off for a while (3+ weeks) and it didnt really ever clear them up fully so not sure its worth the 20 squid. Link to comment Share on other sites More sharing options...
andypotatoes Posted August 16, 2009 Share Posted August 16, 2009 Fungus gnat larvae don't do much damage to larger plants, but they can be very damaging to newly rooted cuttings - it's with your seedlings and in propagation areas you really have to watch the buggers. They can be controlled biologically, with Hypoaspis, but they come back anyway. If you clean up well between crops and don't leave any old compost around they shouldn't get out of hand. They love moist peat. Link to comment Share on other sites More sharing options...
Amnesia Posted August 16, 2009 Author Share Posted August 16, 2009 I forgot to ask,should i wash the sharp sand through first?,also it might sound like a stupid question but do i just leave the sand in the pots then until harvest time? If this sand trick really works then would it be a good idea to put the sand on top on your final re-pot in future as a precaution to stop any larvae from hatching? (obviously it would be no good doing it in earlier pots as you would get too much sand mixed in with the soil on pot-ups!) I'm in my second week of flowering by the way. Link to comment Share on other sites More sharing options...
lazi Posted August 16, 2009 Share Posted August 16, 2009 How about a layer of hydroton on top of the pots and hit them with the Henry every day till they're gone. Link to comment Share on other sites More sharing options...
Amnesia Posted August 16, 2009 Author Share Posted August 16, 2009 How about a layer of hydroton on top of the pots and hit them with the Henry every day till they're gone. I take it that's clay pebbles? ,excuse me for being dumb but wtf is "Henry" If they do work that would be excellent as you can put a layer on each re-pot,Is this a tried and tested method then? Link to comment Share on other sites More sharing options...
andypotatoes Posted August 16, 2009 Share Posted August 16, 2009 Hydroleca is an excellent topping, and will help keep down the sciarid flies. It also stops the soil drying out so much, etc. I re-use it about 3 times. Henry is the hoover I think, and scribbles advice is really good - I just squash them if I see them, but I bet that works better. Link to comment Share on other sites More sharing options...
BluePixie Posted August 16, 2009 Share Posted August 16, 2009 I had success in the past with a combination of sticky traps to get the adults, and extending the gap between waterings by a extra day for a couple of waterings so to as to dry out the larvae. 1 Link to comment Share on other sites More sharing options...
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