Grow Mediums Gnats and coco

[Odissey]

Hi everyone!

So I am in the middle of grow in pure coco and I have been watering everyday to 20 % runoff. I started seeing some gnats and I kind of ignored since it was just one here and there, but recently they seem to be everywhere! As in: I open the tent and I see dozens of flying mosquitoes everywhere in the tent.

My dilemma now is that I want to keep getting the benefits of hydro in coco by watering frequently (she is now starting to flower heavily), but I feel that maybe I should let the coco dry to control the gnats.
Will I damage the plant by letting the coco dry once to control the pest? Should I ignore the problem?

Thanks in advance!

Best,

Odissey

 

[Buzzard]

As an alternative.....I like to sprinkle a dusting of diatomaceous earth on the surface, then water it in and sprinkle a second dusting and leave on the surface. It kills the flies that land on it an the stuff that gets watered in kills the larva.

 

[Odissey]

Thanks for the reply. Unfortunately, that is difficult to get where I live. Any alternatives?

 

[Odissey]

If anyone has the same problem, I tried laying out some dishes with apple vinegar and soap and I have caught at least 20 of them. I am hoping this plus letting the surface of the coco dry out will solve the issue.

 

[parsing_trees]

You could try bottom-feeding the coco until the gnats die off, that will dry out the top surface and interrupt their lifecycle, while still keeping the roots happy. Put your container(s) in some sort of tray, bucket(s), or whatever, then pour in some nutrient water. Maybe start with a half inch to an inch or so, but ideally give them as much as they're able to absorb within a couple hours. Standing water shouldn't cause problems (aside from increasing humidity a bit) if it doesn't stick around. You can water the tray/bucket more once it's all absorbed; this is what autopots automate.

This is the main way I water, it works particularly well with several plants in smaller containers. I top-water once a week or two, to wash out potential salt buildup. I haven't had any issues with bugs yet. Good luck!

 

[31drew31]

I was going to suggest the same thing as above, water from below and let the coco soak it up so that the top can stay dry for a while. Add sticky traps or like you've done some apple cider vinegar + a drop of soap to catch as many flyers as possible.

Another option to diatomaceous earth that I've read is to just put an 1-2" layer of sand at the very top, the idea is the flying gnats aren't able to dig down to the dirt and lay their eggs, stopping the cycle. Personally I've never tried the sand and just use sticky traps + drying out the top layer to combat them.

 

[Odissey]

Sounds like good advice guys! I will try it bottom feeding then. I think I have trapped most adults in the vinegar traps as I dont see any gnat anymore, but there probably are eggs still so the bottom feed should dry them out. Thanks!

 

[Need4Weed]

I've been fighting gnats the last 2 grows. Sand need to be coarse, (think cement sand), but if you don't water slowly it will wash a lot of the sand right through the coco and out of the pot. If you can find Hydrogen Peroxide, (it's hard to find now since the Covid19 pandemic), mix it with 5 parts water and water like normal, (no nutes, nothing but HP and H20). This will kill the eggs and larve, but not adults. I also slice potatoes in half and place them cut side down on the top of the coco. Adults and larve seem to be more interested in potatoes than plant roots. Finally, you need lots of yellow sticky traps like these!
2
2 of Kensizer 30-Pack Dual-Sided Yellow Sticky Gnat Traps for Indoor/Outdoor Flying Plant Insect Like Fungus Gnats, Whiteflies, Aphids, Leaf Miners, Thrips, Other Flying Plant Insects - 6x8 Inches
Sold by: Kensizer Inc

I just ordered 4 more packs. Not only do you hang them everywhere you see gnats, but also put them on top of the potatoes in each of you plants. It really helps to knock em down and they also give you an ideal of how big the infestation is! Hope this helps!

 

[Need4Weed]

I've been fighting gnats the last 2 grows. Sand need to be coarse, (think cement sand), but if you don't water slowly it will wash a lot of the sand right through the coco and out of the pot. If you can find Hydrogen Peroxide, (it's hard to find now since the Covid19 pandemic), mix it with 5 parts water and water like normal, (no nutes, nothing but HP and H20). This will kill the eggs and larve, but not adults. I also slice potatoes in half and place them cut side down on the top of the coco. Adults and larve seem to be more interested in potatoes than plant roots. Finally, you need lots of yellow sticky traps like these!
2
2 of Kensizer 30-Pack Dual-Sided Yellow Sticky Gnat Traps for Indoor/Outdoor Flying Plant Insect Like Fungus Gnats, Whiteflies, Aphids, Leaf Miners, Thrips, Other Flying Plant Insects - 6x8 Inches
Sold by: Kensizer Inc

I just ordered 4 more packs. Not only do you hang them everywhere you see gnats, but also put them on top of the potatoes in each of you plants. It really helps to knock em down and they also give you an ideal of how big the infestation is! Hope this helps!

Btw, I remove the potatoes before each feeding and place them in a bowl of HP or soapy water. Make sure you wipe away any larve you see on the potatoes if you use soapy water.

 

[VitaMan]

If you can find Hydrogen Peroxide, (it's hard to find now since the Covid19 pandemic), mix it with 5 parts water and water like normal,

Thanks N4W. Dang gnats have cost me lots of seeds over several starts so I have to go all out.

I picked up some 29% peroxide last week, but it is not clear whether people are using 5:1 of that, or the 3% peroxide drugstore variety. Can you clarify?

I have been running an ozone generator in the closet every 4 hours for about a week, to kill any mould and other nasty micros that might be in there.

I am going to treat 4 pots of soil (nothing planted just yet) before I top with Diatomaceous Earth. Of course, I have yellow Saver's Sticky Sticks too.

Larvae decimated my seedlings even though I only found around 10 adult gnats on the sticky papers, leading me to wonder if the little buggers were imported with a bag of soil. I suppose each one of them could have laid hundreds of eggs.

Oh yeah- I live on one of the many leaky townhouses that were built by greedy contractors in the mid 80's. No obvious leaks, but very high humidity and mould loves this place. So, I am also going to treat all of the corners and seams of the closet with anti-fungus Kilz Paint and Sealer.

I have to get this right- dispensary prices are ripping me off and I really need to have a harvest this August.