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Will this work for fungus gnats?

G

ganjygav

Hi people,
I've got a fungus gnat problem, had them before but they have never damaged plants before but the tops of my plants are yellowing with no other visible signs of any other problems.
I have noticed a lot more gnats this past week though flying around.

So I need to kill the larvae in the soil. I work a lot and find it difficult to get to the grow shops before closing. So today sent my girlfriend to get some gnat off and ask for anything else to get rid of the larvae in my soil.
I've come home and the shop sent her back with a powder called snake killer, it's bacillus thuringiensis and a liquid called fungi killer.

Both sprays for folia application which from what I read shouldn't be used within 3 days of each other.

What I really need to know is will any of this stuff kill fungus gnat larvae in the soil? I'm not lazy or stupid I have looked on Google but nowhere can I find anything about these products being used for killing larvae in the soil.

I know I've prattled on so thanks if you made it to the end haha
 
R

RB56

Active member
Veteran
Foliar won't do it for larvae, need to treat the soil. I'd use Gnatrol. 4 drenches, 3 days apart.
 
justanotherbozo

justanotherbozo

Active member
Veteran
...unless you have a large op, say bigger than 10x10, then all you need is sticky traps which don't affect the larvae in the soil except that it's the flyers who lay the eggs that become larvae.

...even in a 10x10 space a half dozen yellow sticky traps and your gnat problem will be solved within 2 weeks.

...totally organic and put and forget easy.

peace, bozo
 
G

ganjygav

RB56 said:
Foliar won't do it for larvae, need to treat the soil. I'd use Gnatrol. 4 drenches, 3 days apart.
Click to expand...

Not available in the uk, it's annoying a lot of products are being taken off the shelf here in the UK for stupid reasons. Miteywash was banned because it killed a certain house spider, gnatoff was recently banned. I didn't even know and as far as I understand both these products contain nothing toxic.

Thanks for confirming it wouldn't work for soil larvae. I didn't think it would and I'm annoyed with the grow shop. They must have known it would be no good.
 
G

ganjygav

justanotherbozo said:
...unless you have a large op, say bigger than 10x10, then all you need is sticky traps which don't affect the larvae in the soil except that it's the flyers who lay the eggs that become larvae.

...even in a 10x10 space a half dozen yellow sticky traps and your gnat problem will be solved within 2 weeks.

...totally organic and put and forget easy.

peace, bozo
Click to expand...

Tiny 1.5mx1.5m with 6 plants. I've put the traps up last night so that's good. I panic though and wanted to kill the crap out of the larvae asap seeing as they are affecting two of my plants health wise.
I'm 17 days into flower that was my concern with speed.
 
R

RB56

Active member
Veteran
I've never had luck eradicating an infestation as sticky traps. I use them - as monitors. You have to break the soil/air cycle. I did this in soil and now do it in coir:
https://www.icmag.com/ic/showthread.php?t=290400

Doing that keeps the adults from laying eggs in the medium and larvae from escaping the medium. If you do something like that to break the cycle, you may be able to get them with sticky traps since no new fliers will emerge. no new eggs will be laid.

Gnatrol is Bacillus thuringiensis subsp. israelensis, so if you can figure out a way to make a soil drench from the product you have containing Bacillus thuringiensis, you may be set.
 
G

ganjygav

RB56 said:
I've never had luck eradicating an infestation as sticky traps. I use them - as monitors. You have to break the soil/air cycle. I did this in soil and now do it in coir:
https://www.icmag.com/ic/showthread.php?t=290400

Doing that keeps the adults from laying eggs in the medium and larvae from escaping the medium. If you do something like that to break the cycle, you may be able to get them with sticky traps since no new fliers will emerge. no new eggs will be laid.

Gnatrol is Bacillus thuringiensis subsp. israelensis, so if you can figure out a way to make a soil drench from the product you have containing Bacillus thuringiensis, you may be set.
Click to expand...

Maybe I could spray enough to saturate the top 2 inches of soil?
 
justanotherbozo

justanotherbozo

Active member
Veteran
...yeah, i grow in 4x4 tents and have done so for nearly 10 years and EVERY time i've had a gnat infestation, and i grow in coco so that means MANY times over the years, i have solved my problem with sticky traps ONLY!

...sticky traps don't work over night but they do work, gnat flyers are attracted to the color yellow so they do land on the traps and get stuck and every one that gets stuck is one more egg layer you don't need to worry about.

...you want to speed the process up? ...add more traps.

...if you grow in a greenhouse or a warehouse then traps would be inadequate but for a small op like mine and yours yellow sticky traps and a little patience is all you need.

...another side benefit is that yellow sticky traps is TOTALLY non-toxic to your plants.

peace, bozo

PS: if the gnats don't appear to be attracted to the traps then they probably aren't gnats but might instead be white flies which, i believe, are attracted to blue sticky traps.
 
R

RB56

Active member
Veteran
ganjygav said:
Maybe I could spray enough to saturate the top 2 inches of soil?
Click to expand...
I don't know. The bacteria only work against the larvae. The larvae only live in the medium. It doesn't make sense to me to have the bacteria in a foliar treatment but I did check Snake Killer and that's what they recommend. All of these bacterial treatments require living bacteria.

Amazon UK sells Gnatrol WDG.
 
G

ganjygav

I've been reading....
There's 2 strains of bacillus thuringiensis that gardeners in general use.
There is one for coating the roots and killing larvae in the soil that eat them - israelensis (the one I need)

The other strain is used to coat leaves to kill leaf eaters - Kurstaki (what the shop sold my girlfriend)

So what I have is no good for my needs, I'm really annoyed at the grow shop owner. My girlfriend had it in text that I needed treatment for fungus gnat larvae and at the end of the day who owns a grow shop and don't know what's used for what?

I've just got another 10 yellow traps and I will stick them up tonight as well as sprinkling some DE dust on top of soil. I spoke to another grow shop on the phone and he said he would get something in stock by monday.
I'm gonna go give the other grow shop an education on their products tomorrow and ask for a refund.
 
D

DocTim420

The Doctor is OUT and has moved on...
A post I made in different thread--this might help (think Amazon?).
DocTim420 said:
As we all know, Bacillus thuringiensis serotype israelensis (BTi) is effective natural pesticide to control Fungus Gnats. So how do we measure BTi? Which product is the best "deal" for buying BTi?

Well, that question requires a little back of the envelope math before one can actually compare different BTi products. You see, BTi is measured in International Toxic Units (ITU) at various concentrations ranging between 100 to 7,000 ITU/mg. The "Active Ingredient Percentage" on the label is just part of the story...gotta include the amount of ITU/mg.

An 8% "active ingredient" product formulated with 1200 ITU/mg has 96 ITU (1200 x 0.08) for each milligram of product.

A 3% "active ingredient" product formulated with 7000 ITU/mg has 210 ITU (7000 x 0.03) for each milligram of product.

Hmmm, that means the 3% products has nearly twice the amount of ITU than the 8% product. WTF?

Also, application methods are different. Some products are RTU (ready to use) for both soil and water applications, others like Vectobac require the preparation of fermentation slurry to activate the BTi, and some are only water soluble (not to be mixed directly with the grow medium).

Since not all BTi products are "equal", I have prepared a comparison of the "usual suspects" and correlated everything to cents per million ITU.

picture.php


Gnatrol is the most affordable, but can only be used in a liquid suspension form--you can not add the powder directly to the grow medium.

Bits is the 2nd most affordable and can be added to both water and the directly to the potting soil. When added to the water, BTi is instantly activated...but when mixed with potting soil, BTi is gradually activated (time release of sorts) for about 21 days. Bits are basically corn cob bits sprayed with BTi.

Dunks are slow acting (gradual release as the "donut" dissolves) and can be added to the potting soil directly--but must be crumbled to a powder like consistency (PIA). Dunks are pressed donuts made of gypsum and cork bits sprayed with BTi.

I have no experience with Vectobac products but a special fermentation slurry must be prepared before the BTi is activated (an additional step that most BTi products do not require).

Microbelift BMC is already in liquid form and like Gnatrol, it must be diluted in water before use...and from my analysis, is not a bargain.

I previously used both Gnatrol and Dunks, but for the past few years I exclusively use Bits for my source of BTi ($120 for 5 gallon bucket). I mix Bits directly to my water (30 ml/20 gallon rez), mix Bits directly in the potting soil (5 ml/5 gallon container) and mix Bits with my top dressing fertility (7.5 ml/5 gallon container).

One product for all. Admittedly, I could use Dunks form my water rez, but since that rez is used and refilled daily, I prefer the faster acting Bits over the slow release Dunks.

So there you have it. If there are other BTi products you want included in my analysis, please let me know and I will be more than happy to add them.
Click to expand...
 
L

LBones

New member
Hey ganjygav, does the damage look similar to this by any chance?

I've had significant fngus gnat problems in the past. Similar to what someone else posted on here, I let the soil get a bit more dry between waterings, cover the top 2-3inches of soil with perlite, and lots of sticky traps. This works for me without fail and usually takes less than a week to get rid of them.
 
knuckles

knuckles

Active member
Veteran
The ONLY thing that that has ever worked for me,on a consistent basis are nematodes used two weeks apart ongoing.
 
P

philberg

New member
Mosquito dunks will rid the grow of fungus gnats. Just crumble one up and sprinkle it on the top of the medium and say good bye to gnats for good. Just a small pinch of dunk will get the job done in about 3 weeks.
 
JAWS

JAWS

Well-known member
ENOUGH

PLEASE listen to me on this issue.

get $25.00 go to home depot and buy this PRODUCT.



get the granulars not the LIQUID.

spread out a THIN layer over your soil then either water or wet it down with a spray bottle.

you "WILL SEE" results by the next day, by weeks end your GNAT problem is no longer a problem and never will be again as long as you have this product in house..

like anything when you bring new soil in it will also need treated..
do not touch with your hands, just sprinkle with a spoon and throw it away.

if you have GNAT and you do not go get this PRODUCT then enjoy your GNATS..




do it :)
 
D

DocTim420

The Doctor is OUT and has moved on...
JAWS said:
ENOUGH

PLEASE listen to me on this issue.

get $25.00 go to home depot and buy this PRODUCT.

[URL=https://www.icmag.com/ic/picture.php?albumid=69789&pictureid=1774245&thumb=1]View Image[/url]

get the granulars not the LIQUID.

spread out a THIN layer over your soil then either water or wet it down with a spray bottle.

you "WILL SEE" results by the next day, by weeks end your GNAT problem is no longer a problem and never will be again as long as you have this product in house..

like anything when you bring new soil in it will also need treated..
do not touch with your hands, just sprinkle with a spoon and throw it away.

if you have GNAT and you do not go get this PRODUCT then enjoy your GNATS..




do it :)
Click to expand...

NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Investigate the active ingredient's half-life. Your "jaw" will drop to the floor...especially the half-life for organic soil.
 
troutman

troutman

Seed Whore
A dilute solution of hydrogen peroxide will kill them. :tiphat:

What you need is a 0.6% solution. Don't use a stronger solution.

Mix 1 part of 3% hydrogen peroxide with 4 parts of water by volume to get 0.6%.

Soak the soil and bye bye fungus gnat larvae.

Note: Leaving the top of you soil dry out a little will discourages fungus gnats. Constant moist soils are what they like.
 
D

DocTim420

The Doctor is OUT and has moved on...
Yep...H2O2 will work, but it will also annihilate the microherd too. For organic soil based grow mediums, a thriving microherd is almost required. But H2O2 will do the job as well as detox the grow medium.
 
troutman

troutman

Seed Whore
DocTim420 said:
Yep...H2O2 will work, but it will also annihilate the microherd too. For organic soil based grow mediums, a thriving microherd is almost required. But H2O2 will do the job as well as detox the grow medium.
Click to expand...

Some soil could be kept in a separate container with a screen that doesn't allow fungus gnats to leave or enter.

This soil once free of fungus gnats could be used to inoculate the pots again.
 
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