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Fungus Gnats, Neem Meal and Beneficial Fungi


New Member
I am growin in LOS and have a pretty huge gnat infestation. Ive let it dry right out a few times and re inoculated with mycorrhizae, put a inch thick layer of sand on top and also top dressed with diatomaceous earth but they just keep coming back.
Ive heard a lot of people adding neem meal to their soil as an insect repellant but it is also a fungicide.
My question is, since the point of builing a living soil food web is to have a healthy colony of fungi, bacteria and microbes wont the neem throw that out of balance?
Cheers guys n gals :)
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Active Member
Heya, i don't know what LOS is, but it seems like soil if you can let it dry out ...

i would go for them at their larva stadium, not using anything that kills everything but with biological means :)

Nematodes - Steinernema feltiae
Entomopathogenic nematode - Wikipedia

Those are insect parasites (nematodes) which penetrate into the larvae. The worms live in symbiosis with bacterial strains, the bacteria decompose the larvae which in turn feed the nematodes.

Advantages: The most effective fighting within the shortest time.
Disadvantages: nematodes can not be stored. Within less than 1 week, they must be used. After the treatment with nematodes, the substrate must not dry for a few weeks, the worms migrate into the earth in search of food. Narrow range of temperature (15-25 ° C)

Bacillus thuringiensis Israelis
(dunno if other bac. strains work against fungus gnats as well, but this one works)
Bacillus thuringiensis israelensis - Wikipedia

The bacteria are eaten by the larvae of fungus gnats. Bacterial toxins are released in the intestine and the larvae decompose.

Advantages: Unlike the nematodes bacteria can also be used in liquid systems. Are also effective against mosquito larvae. Can be stored (small container) and are easy to use (a few drops to the water).
Disadvantages: earth must be regularly watered, so that the bacteria are distributed evenly. several applications are needed.

predatory mites: Hypoaspsis family
Hypoaspis miles - Wikipedia

The mites are shipped in peat substrate, which is to distribute to the affected substrates. The predatory mites feed on the larvae. Are all the larvae destroyed, they can starve for several weeks.

Advantages: also act against springtails.
Disadvantages: slow but long-term fight.

those 3 won't have an impact on other life forms in your soil except larvae :)

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New Member
Hey mate thanks for all the great info, some good ideas there! The problem with the mites and nematodes is that i have already added diatomaceous earth so i think that would mess with them but the bacteria sounds kool.
I actually think the diatomaceous earth has worked, there seems to be alot less gnats it must have just taken longer then expected (i added arund 2 weeks ago...
Cheers :)
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