Fungus Gnats

Noonin NorCal · Feb 20, 2017

Hi friends. I haven't been on the boards since last seasons outdoor. Im now 3 weeks into flowering indoor with organic soil in 3 gallon geo pots.... Phantom is the strain Cherry Pie X GDP. I seem to have some fliers buzzing around the base of my soil, I placed some sticky papers in the room just right under the canopy, killed some gnats. I was wondering about doing a top layer/top dress with some diatamcous earth. I was just wondering when i should apply it?
Doesn't the stuff pretty much stop working once you water, if the stuff gets wet? Im currently now watering every 3-4 days, letting the soil dry out almost completely

Ive also heard something about doing a root drench with BT? Also heard something about a top layer of perlite? Thanks

luvtogrow · Feb 20, 2017

I grow indoors in norcal and found small amount of mosquito dunk sprinkled on top of soil kills the larvae. Perlite works to kill adults when you push the surface to crush them, otherwise not that helpful. Sticky traps to measure infestation. Diatomaceous earth can work i've heard but can also limit air exchange (i've read).

FunkBomb · Feb 20, 2017

If you put a 1/2 -3/4 inch layer of perlite on the top of your soil it will help fix the fungus gnat issue. Keep the yellow sticky traps out as an added measure. This worked well for me when I had an outbreak of gnats from a few bags of soil.

-Funk

TrueReligion · Feb 20, 2017

The finer the grain of perlite is better to a certain point.

Seal everything off and panda plastic down

chronosync · Feb 20, 2017

DE wont kill bugs when its wet, but when its dry nothing can stand to survive its touch. i love it for that fact but i try to keep it out of my medium. i have been coming up with various things to combat gnats lately and one of them is inspired by rb56 using fiberglass screen.

if you take a circle of it a bit larger than the pot, cut it down the middle to the center and make an x cut there too, you can place it on top of your medium around the stem and over the pot and put DE right on top.

the screen also holds on to alot of the DE so pretty much anything trying to get into or around it is doomed. when dry of course.

i grow in coco so i dont want it in my pots, it seems to get gummy and id imagine the same for soil.

G.O. Joe · Feb 20, 2017

Gnatrol WDG is the nuclear option of reliability and effectiveness. Sticky things lit with penlights in the dark knocks down fliers fast.

Medfinder · Feb 20, 2017

sand layer on top... what about the bottom? check that too.

yellow stick traps...

using bacillus israelis is the best tho

DocTim420 · Feb 20, 2017

Mosquito Bits are a good affordable source for BTi--and easy to dispense. I mix in water at the rate of 5ml/gal and sprinkle 7.5ml on the surface of my plants in 5 gal containers. Amazon has good prices.

RB56 · Feb 20, 2017

chronosync said:
DE wont kill bugs when its wet, but when its dry nothing can stand to survive its touch. i love it for that fact but i try to keep it out of my medium. i have been coming up with various things to combat gnats lately and one of them is inspired by rb56 using fiberglass screen.

if you take a circle of it a bit larger than the pot, cut it down the middle to the center and make an x cut there too, you can place it on top of your medium around the stem and over the pot and put DE right on top.

the screen also holds on to alot of the DE so pretty much anything trying to get into or around it is doomed. when dry of course.

i grow in coco so i dont want it in my pots, it seems to get gummy and id imagine the same for soil.

Awesome. Here's the link to what I do:
https://www.icmag.com/ic/showthread.php?t=290400
Literally went from an infestation every grow when it's warm outside to one or two fliers showing up on sticky traps periodically. Super easy to break down and reuse. Nice not to deal with the bastards anymore.

Noonin NorCal · Feb 20, 2017

I did a root drench with GoGnats. It seems it didn't really work. i noticed a bunch on the sticky papers. i love the smell of GoGnats lol its got cedar oil in it

I wood · Feb 20, 2017

You should take a real close look at them and be sure they are not winged root aphids.
They appear very similar at first but respond differently to pesticides, that is bt doesn't work for them at all.
Under magnification the difference is easy to see.
I had winged root aphids for at least a year or two before I figured this out myself.
Hopefully I'm wrong but bt not working is a bad sign.
Good luck.

HqFarms · Feb 20, 2017

First of all are you sure it is fungus gnats and not flying root aphids? A layer of play sand will prevent gnats, about a half inch thick. DE will work if you can bottom feed, leaving the DE dry. Slices of potato will attract the fungus gnats larva and you will know for sure if it is fungus gnats or root aphids

chronosync · Feb 20, 2017

RB56 said:
Awesome. Here's the link to what I do:
https://www.icmag.com/ic/showthread.php?t=290400
Literally went from an infestation every grow when it's warm outside to one or two fliers showing up on sticky traps periodically. Super easy to break down and reuse. Nice not to deal with the bastards anymore.

Very awesome! I somehow missed your thread with pics on it, very helpful, i'll be setting up a few of these just like this now. Thanks RB56!

I do rather like the screen, its pretty cheap where i found it (Home Depot) and will probably find some other uses for it. Screen shade for clones etc,.

hillbil · Feb 21, 2017

Grind up some dunks and use in all mixes and add a few crumbs Every couple weeks when watering. Diatamatious Earth around grow area is helpful or mix in with that perlite layer. Just getting acquainted with Neem Cake and it seems to do a great job. I also spray with Neem if I feel a need. The dunks are effective always over time.

Gnats are everywhere where I live and especially with our un-winter this year. We often import them in our amendments like castings, manures, composts, peat and mixes. I mix a few crumbs of dunks into all newly opened bags of compost or whatever. A few gnats are not worrisome and cause me little concern.

Keeping up with using dunks will work but it takes a couple weeks as the bacteria feed on the larvae.

DocTim420 · Feb 21, 2017

Dunks vs Bits...IMO, Bits are cheaper, easier to use/measure (no crumbling) and last longer (time release over 14-21 days). Both made by the same company so it really is a matter of preference.

hillbil · Feb 21, 2017

Never have seen bits in a store. They are the same and will work but I can get the dunks here. Thanks.

DocTim420 · Feb 21, 2017

https://www.amazon.com/Mosquito-Dunks-117-6-Bits-30-Ounce/dp/B0001AUF8G/ref=sr_1_1?ie=UTF8&qid=1487687959&sr=8-1&keywords=mosquito+bits

5 gallon bucket is about $120 or so.

RB56 · Feb 21, 2017

chronosync said:
Very awesome! I somehow missed your thread with pics on it, very helpful, i'll be setting up a few of these just like this now. Thanks RB56!

I do rather like the screen, its pretty cheap where i found it (Home Depot) and will probably find some other uses for it. Screen shade for clones etc,.

101 uses for that screening. I have it over all air intakes in my rooms. I've also cut holes in 5 gal pails and larger totes, epoxy screen over the holes and use them for washing coir. Seems to be the perfect size and being fiberglass, is much easier to squeeze into places metal screen would make difficult.

Noonin NorCal · Feb 26, 2017

HqFarms said:
First of all are you sure it is fungus gnats and not flying root aphids? A layer of play sand will prevent gnats, about a half inch thick. DE will work if you can bottom feed, leaving the DE dry. Slices of potato will attract the fungus gnats larva and you will know for sure if it is fungus gnats or root aphids

I will give that a shot later when the lights go on at 7 pm. should the potatoes be fork tender lol, JK

Btw. I'm using an 8 x 4 tray. Could i just place the slices on the tray or put them around the base of each plant? Im getting run off when i water. Its not ebb n flow, just smart pots on top of a tray, Thanks

HqFarms · Feb 26, 2017

Noonin NorCal said:
I will give that a shot later when the lights go on at 7 pm. should the potatoes be fork tender lol, JK

Btw. I'm using an 8 x 4 tray. Could i just place the slices on the tray or put them around the base of each plant? Im getting run off when i water. Its not ebb n flow, just smart pots on top of a tray, Thanks

Put them at the base of each plant. The fungus gnat larva will go right for the slices.

Fungus Gnats

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