Fungus Gnat Extermination

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artcore

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I have a small problem with dirt flies and fungus gnat, already have controlled the flies problem but now the aim is to exterminate.

It is likely that the substrate still has larvae so I bought Bacillus Thuringiensis 32 Mill. de uds. (Biothur) but only have instructions for foliar treatment (1gr/liter) and my aim is to kill the larvae that are on the substrate...

What amount per liter I must join to water the plants with Bacillus Thuringiensis?
 
shemshemet

shemshemet

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You need Bti (Bacillus thiringiensis israelensis)

The product you have stated is not for use on diptera (fly order) and will not work on fungus gnats. The reason it only gives foliar rates is because it is used for I believe caterpillars.

You've got to get to home depot or similar for mosquito dunks. Or order the more specialized products (which I don't think are any better, maybe spore count?) specifically marketed for fungus gnats.

Or you could try sprinkling DE (diatomacious earth) on the tops of your pots.
I've heard a layer of sand also works on top.

I usually don't have problems once I crumble up some (about the size of a gel cap advil) mosquito dunks onto my pots.

Others I have heard just can't get rid of em

Good luck
 
caregiverken

caregiverken

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You need Bti (Bacillus thiringiensis israelensis)

The product you have stated is not for use on diptera (fly order) and will not work on fungus gnats. The reason it only gives foliar rates is because it is used for I believe caterpillars.

You've got to get to home depot or similar for mosquito dunks. Or order the more specialized products (which I don't think are any better, maybe spore count?) specifically marketed for fungus gnats.

Or you could try sprinkling DE (diatomacious earth) on the tops of your pots.
I've heard a layer of sand also works on top.

I usually don't have problems once I crumble up some (about the size of a gel cap advil) mosquito dunks onto my pots.

Others I have heard just can't get rid of em

Good luck
Good post!
diatomaceous earth for the win!
a good source of silica too
I've seen people put sand on the top of their soil to keep those gnats out
 
H

happy b

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Yes.diatomaceous earth or sand.
im about to use nematodes to eradicate the larvea and yellow sticky traps and either sand or diat earth on top of soil should do the damage i think.
 
A

artcore

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I have the yellow sticky traps and they work very well, I also let the substrate dry enough time to try to kill the larvae, had for 4 days potato slices on top of the substrate and only found two larvae... I am confident that the problem is almost solved but the Bacillus treatment would give more guarantees...

Unfortunately I have not found BTI for sale in my country so I bought Bacillus Thuringiensis (serotype 3a3b), I did some research and I got the idea that this product was suitable for the problem, not as good as BTI but that would solve the problem... but can not find anything on the doses to water the soil
 
shemshemet

shemshemet

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@artcore
Bt and Bti are both a biological pesticide. Biological pesticides are very pest specific, so no regular Bt will not do any damage to fungus gnats.
 
A

artcore

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@artcore
Bt and Bti are both a biological pesticide. Biological pesticides are very pest specific, so no regular Bt will not do any damage to fungus gnats.

The internet is terrible, there is more misinformation that credible information... it makes sense, each species attacks a specific pest.

I will try the mosquito dunks, I think that I can find them nearby.

I have some pebbles, can I use them to put on top of the soil?
 
sixstring

sixstring

7,079
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You need Bti (Bacillus thiringiensis israelensis)

The product you have stated is not for use on diptera (fly order) and will not work on fungus gnats. The reason it only gives foliar rates is because it is used for I believe caterpillars.

You've got to get to home depot or similar for mosquito dunks. Or order the more specialized products (which I don't think are any better, maybe spore count?) specifically marketed for fungus gnats.

Or you could try sprinkling DE (diatomacious earth) on the tops of your pots.
I've heard a layer of sand also works on top.

I usually don't have problems once I crumble up some (about the size of a gel cap advil) mosquito dunks onto my pots.

Others I have heard just can't get rid of em

Good luck
can you be more specific on the mesquito dunks please? i have some of these but i have never used them.i thought about smashing up one and using like a 1/3 of it in a gallon of water and doing a soil drench.but it sounds like you are just using i tiny piece of it the size of a pill and putting it on top of your soil?thanks
 
shemshemet

shemshemet

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@sixstring

Over time my fungus gnat problem has 'naturally' declined aka I didn't do much and the flies stopped anyways.

But what I usually do when I see a population burst, is take about maybe a tenth of the thing, crushed it up in my fingers, and apply it to a ~4 gallon pot.

I don't find the application rates to be too important...but what do I know?

You could do your method, but I like the assurance that if the spores are on the material, I want the material in my pot.
 
Dunge

Dunge

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Gnatrol is the only product I know of that contains Bti in quantities able to negatively impact larval survival.
I also use nematodes.

I found that my cloning tray was the primary source of gnats.
The Rapid Rooters are like maternity wards for those little pests.
 
Underthesun

Underthesun

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I just picked up some Microbe-Lift BMC Bti at the shop. Dude says everyone says it works great. Also an old thread back from '11 on here says it knocks em out.
 
B

brimck325

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i've read numerous times that bt will not kill gnats....i think someone forgot to tell the gnats...i use it with very good results.
 
A

artcore

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good to know... how do you use it? foliar treatment or directly to the soil with water?

I solved my problem with the yellow sticky traps and only watered the plants 2 times in 12 days instead of 3 times...
 
B

brimck325

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i do a soil drench....5 ml per gal if infested, 1ml per gal as preventative weekly.
 
shemshemet

shemshemet

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It's not that the original formulation of Bt won't kill gnats, it is that it CAN'T kill gnats. As it's mode of action is specific against caterpillars. My understanding is lepidoptera and coleoptera. Where Bti (subspecies israelensis) goes for 'lower tiered' diptera.

@brimck325 If your Bt killed your gnats, you had Bti. If it wasn't Bti, something else coincidentally happened after your application.

"Bt action is very specific. Different strains of Bt are specific to different receptors in insect gut wall. Bt toxicity depends on recognizing receptors, damage to the gut by the toxin occurs upon binding to a receptor. Each insect species possesses different types of receptors that will match only certain toxin proteins, like a lock to a key.

It is because of this that farmers have to be careful to match the target pest species with a particular Bt toxin protein which is specific for that insect. This also helps the benifical insects because they will usually not be harmed by that particular strain of Bt."
Source: http://www.bt.ucsd.edu/how_bt_work.html
 
A

artcore

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May have to do with the gnats species, certainty that the gnats species may vary from country to country and from continent to continent. It is almost impossible to buy BTI in Europe but all growshops sell BT and recommend BT for sciariad flies/fungus gnat.

From what I noticed, in Europe we do not have problems with diptera and that's why the growshops not sell BTI... unfortunately I can not find the uk420 topic where I read the name of the fungus gnat specie that we have in Europe...
 
B

brimck325

215
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It's not that the original formulation of Bt won't kill gnats, it is that it CAN'T kill gnats. As it's mode of action is specific against caterpillars. My understanding is lepidoptera and coleoptera. Where Bti (subspecies israelensis) goes for 'lower tiered' diptera.

@brimck325 If your Bt killed your gnats, you had Bti. If it wasn't Bti, something else coincidentally happened after your application.

"Bt action is very specific. Different strains of Bt are specific to different receptors in insect gut wall. Bt toxicity depends on recognizing receptors, damage to the gut by the toxin occurs upon binding to a receptor. Each insect species possesses different types of receptors that will match only certain toxin proteins, like a lock to a key.

It is because of this that farmers have to be careful to match the target pest species with a particular Bt toxin protein which is specific for that insect. This also helps the benifical insects because they will usually not be harmed by that particular strain of Bt."
Source: http://www.bt.ucsd.edu/how_bt_work.html
the only thing i can think of is the gnats in larva or pupa stage must be very close to a caterpillar...i use bt for caterpillars. i can't explain because i don't know why it works, but it does.
 
shemshemet

shemshemet

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143
Yes the species may vary, but the mode of action and receptors are similar in families and therefore work on different species.

If a grow shop recommended regular ol' Bt as a fungus gnat solution, I would not recommend going back to that shop.

Again if your Bt and not Bti is working on fungus gnats, it is because it is mislabeled or another coincidence.
 
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