Fungus gnats

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Extacie

Well-Known Member
Hey everyone, just yesterday I noticed a little gnat-like looking thing fly up onto a leaf. I have been having issues with my plants that are 12 days into flower. The lower leaves that aren't getting much light keep turning a brown/grey/blackish color which either end up falling off or I pick off.

After reading through my books & serval forums I have came up with the conclusion that I am getting mold on the leafs through excessive moisture at night. Not quite sure where the gnats came from as I use fox farm Potting soil that is suppose to be sterilized. I have been trying to fix the moisture issue by leaving a vent or two open on the tent at night (didn't before b/c was worried about light leaking in)

So after reading I have came to the conclusion that the best approach is to:

• put some sand over the top layer of soil + cover drain holes with it
•let the soil get very dry inbetween waterings, to the point where the plants start to show slight signs of stress
•use gnatrol or some type of bti to flush the soil with (just bought gnatrol off amazon)
•I am also getting a dehumidifier ASAP & have two fans blowing to help with air circulation, will add another when available.

I know this is not a huge deal but I just want to fix it early on before it spreads to my other babies & actually becomes an issue.

MY MAIN QUESTION:
I want to open up the tent to go inspect/pick off any molded/decaying leafs. My fear is that by opening up the tent I could possibly allow some gnats to fly out & get to my other 9 that are vegging & uneffected (to my knowledge). SO-Should I wait until I recieve the sand/sticky traps/gnatrol/let my soil dry out some & then just do it all at once so I have less risk of the gnats spreading, or do I go ahead & pick off dead leafs now & enter/exit the tent serval times within the next day?


One final question: hydrogen peroxide vs gnatrol or some other type of bti? Which is more effective?

Thank you so much everyone!
 
I'm also interested in learning more about fungus gnat control specific to organic growing. Sticky traps are more about identifying problems than solving them. Hydrogen peroxide works but will also kill your beneficial micro-organisms. I resorted to using a product called Mosquito Bits last year and they worked wonderfully, but I was never able to figure out what they may have done to my organics. If anyone has a knock out product for gnats that is also organic friendly, please share!
 
Yeah but I figure the more adults I can catch on sticky traps, the less adults there are to lay eggs. They say they can lie up to 1,000 in a lifetime. Personally, I am not really worried about an organic approach. I just wanna get rid of the fuckers ASAP!

With sand, what type should be used? I've read that play sad has too big of particles so will not work? My local hardware store has tube sand meant to weight down the bed of a vehicle in the winter months. Will this work? If not, what type of sand should I order online?

So mosquito bits worked pretty good?
 
My main concern/question:

•The sand thing in previous post
•should I pick off effected leafs now or wait till soil dries out & I have all materials to fight them off to do it all at once? I worry about letting them out of the tent & effecting my other plants that are smaller in the veg stage. Currently have azamax & lemon grass oil. Waiting on my gnatrol/fly traps in the mail.
 
Sorry, I'm not familiar with the sand approach.

Mosquito bits definitely worked.

Pyrethrum bombs wiped out the living gnats but they lay their eggs in the soil to return after the pyrethrum burns off. I will plant pyrethurm chrysanthemum next year as an experiment to see if they help prevent pests. Anybody already doing this?
 
I just started using Gnat Nix from Growstone. Its like the sand, but works a little better (stays in place),,, This basically creates a barrier between the soil and the Gnats so they cant get to it, and the ones that do cant get out. I was using Perlite as a top dressing for a while, and it works, just not great.

You can also use a Larvecide in your mix to kill residual larvae that get into the soil.. I am a coco guy, and I water daily, so Gnats just love me.
 
I've read on it some, but not a whole lot of info on the gnat nix I could find unfortunately. Seems like a neat idea. Seems sort of expensive though.
How long have you been using it & how are the results so far? Haha I bet they do to! A larvaecide being like gnatrol or some bti?


Bugeye: I'm assuming pyrethurm chrysanthemum you mix in with the soil? I'm def gonna have to look up pyrethrum bombs.


Thank you both very much for your help.
 
Extacie said:
I've read on it some, but not a whole lot of info on the gnat nix I could find unfortunately. Seems like a neat idea. Seems sort of expensive though.
How long have you been using it & how are the results so far? Haha I bet they do to! A larvaecide being like gnatrol or some bti?


Bugeye: I'm assuming pyrethurm chrysanthemum you mix in with the soil? I'm def gonna have to look up pyrethrum bombs.


Thank you both very much for your help.
Click to expand...

http://en.wikipedia.org/wiki/Diatomaceous_earth
 
Extacie said:
I've read on it some, but not a whole lot of info on the gnat nix I could find unfortunately. Seems like a neat idea. Seems sort of expensive though.
How long have you been using it & how are the results so far? Haha I bet they do to! A larvaecide being like gnatrol or some bti?


Bugeye: I'm assuming pyrethurm chrysanthemum you mix in with the soil? I'm def gonna have to look up pyrethrum bombs.


Thank you both very much for your help.
Click to expand...


This is my first run with it,, and its not really expensive, I think the bag cost $12 and I have covered 4 3gallons and 6 2gallons and still have some left over. So far I have only seen 2 Gnats in the room, when I would normally have them crawling around cause I water daily, so my coco stays very wet.

I use DE powder around the perimeter of my room and any ventilation areas.. its good stuff too!!
 
Extacie said:
Bugeye: I'm assuming pyrethurm chrysanthemum you mix in with the soil? I'm def gonna have to look up pyrethrum bombs.
Click to expand...

I usually grow some ornamental flowers around my greenhouse anyway. I plan to crumple up the dead head flowers around the base of the plants.
 
That's one I haven't heard. Love it! But won't help with larva in your soil unfortunately. But watching them die is very satisfying.
 
Also, fungus gnats won't hurt your grow...unless they are in great numbers or you have lot's of plants to care for, creating more work for a grower, with less time to deal with bugs and a greater chance for things to get out of control.

I've had the little bastards fly around my grow and if I can, I just kill them by a swift swat. Over-watering plants is a breeding ground for FG's, so back off on watering so the larva won't survive (let the top of your grow medium dry out real good). I did this and they never really populated my closet; just 1 here and 1 there, and by the time harvest came, they were virtually gone.

Make sure you check other houseplants for FG's, as they are more prone to be housing them because people tend to neglect a plant that's growing in some corner. Here's a pretty good link about this insect.

http://www.ext.colostate.edu/pubs/insect/05584.html
 
just use insecticidal soap or something along that lines for like a week and you should be good to go. its organic.

also put up some fly strips and stuff i heard h2o2 can take out the eggs a small bit in water not sure on that though.
 
Thank you woody. Sorry, I missed that the first time. I appreciate the help. I ordered some gnat nix & gnatrol yesterday so hopefully they'll come in the mail soon!

Rusty, sounds like you probably deal with that issue a lot. Best of luck!

QUESTION: Can I mix the gnatrol with plant food? Is there any upside or downside to doing it this way? Last time I watered with mainly water (only thing added was some cal-mag as a supplement) & I am suppose to feed this next time I water.
 
Lol I turn 21 in 3 days so will def have to go get some wine & try that. Thank you guitar man, sound advice & really good to hear.

One last major question:

I have 5 or 6 bags of potting soil wrapped in a trash bag outside of my tent with the gnats (only seen one so far) which I have been trying to keep sealed up for the most part. Should I sterilize these before using to transplant my babies in veg?

Hate to do that b/c I've read it kills the nutrients in your soil & I paid 20 bucks a bag for this soil :/
 
I used granulated diatomceous earth in my garden along with drying out the soil and never saw any gnats again. Cactus growers use granulated DE. It is somewhat hard to find. I found some at cactus grower supply websites.
 
Thank you for the tips. Ill see if I can't find some DE somewhere.

What's your alls opinion on my soil? Should I sterilize before transplanting? It's been outside of my tent with the gnats in black plastic trash bags. (One black trash bag has a slight rip in it)
 
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