Fungus Gnats- Are they really a problem?

[Ganjohn420]

Alrighty I'm asking this question because the owner of my hydro store pretty much assured me that Fungus Gnats are not a problem and that they don't eat roots but in fact they just like sweets from nutrients. I read a few threads and the consensus seems that they are not good but I am wondering if anyone can validate this statement. Or also disprove this statement.

 

[habeeb]

from hemp pest and diseases, I have the book right here..

they eat fine root root hairs.

root wounds may serve as a pathway for pathogenic fungi, and they may transit soilborne pathogens ( notably pythium, and fusarium )


I would say the guy is full of shit. also you need to get on this ASAP, as they breed like a bitch.. you need sticky traps, a Bti ( gnatrol or likes ) , and or neem drench. and or nematodes. if you have one buzzing, it can cause another outbreak with the next set.. you need to kill them in all ways possible. you can open the hood if it's sealed hood, they die from the heat when flying at it.. basically read up on how to kill them, as they can get out of control.

 

[ozzieAI]

there are only 2 types of bugs: beneficial and pests...nothing beneficial comes from FG...

 

[LAION]

Google : Fungus gnat damage

http://www.hort.uconn.edu/ipm/greenhs/htms/fngnatser.htm

 

[Crusader Rabbit]

Alrighty I'm asking this question because the owner of my hydro store pretty much assured me that Fungus Gnats are not a problem and that they don't eat roots but in fact they just like sweets from nutrients.

What the hydro store guy said about fungus gnats is true.

Unfortunately he left out the part about fungus gnats having larvae that eat your roots and trash the plants. You'd better get on this!

 

[Ganjohn420]

I suspected they were no bueno, and they definitely multiply quickly, it started with one that i squashed and had high hopes it would turn into nothing more

I am still interested if anyone can prove that they are not harmful just as a devils advocate.

On one of my flower tables I do have alot of exposed roots that have ventured out of the pots. I don't notice them on the roots much but im not in there 24-7 also.

Would the damage from them be visible and specific or more of a cause and effect, i.e. the gnat eats the root which then doesn't function properly creating deficiencies?

 

[Ganjohn420]

Google : Fungus gnat damage

http://www.hort.uconn.edu/ipm/greenhs/htms/fngnatser.htm

What the hydro store guy said about fungus gnats is true.

Unfortunately he left out the part about fungus gnats having larvae that eat your roots and trash the plants. You'd better get on this!

I didn't see these before i posted but thanks Laion that article is legit and gives me a good look at how disgusting these bastids are.

Rabbit you make a good point, i guess its really not the gnat that is the problem but rather their larvae, he never mentioned that part...

 

[soil margin]

They can be a problem if a huge infestation of larvae pops up. Thankfully all you have to do is cover the topsoil in a 1-2 inch thick layer of fine sand and they will never be able to reproduce again. Quick, cheap and easy. Bye bye gnats.

 

[Crusader Rabbit]

They also get into the pots through the drainage holes. If you bottom-water and then let the media dry out so there's a bit of moisture under the containers, the larvae will follow the water down so you can see the little wrigglers in the wet spot on the tray under your pot. With this you can wet the tray with a pyrethrin spray then wet it with enough water to wick up into the base of the media. Then spray the surface. Doesn't get them all but it will quickly cut back an infestation.

If you have a tube of tanglefoot or other sticky goop, you can make your own sticky traps. Go to the paint dept of a big hardware outlet and collect some bright yellow paint color sample cards. Then coat them with a thin layer of sticky. Sometimes you can find a spot where the gnats like to hang out. Put a card there.

Someone here was using paint strainer bags to totally enclose the containers, with the top tied snugly around the stem.

.

 

[trichrider]

if you think you can ignore them, do so, then get back to let us know.

spinosad, DE, and mosquito dunks...these are your tools.

spinosad to kill flyers and adolescents, DE to desicate larvae, and mosquito dunks to keep them down.

multi-pronged attack works best.

(spinosad can do it all in pretty short order, the diatomaceous earth was more of a subjective remedy, and mosquito dunks will work alone but takes about a week).

good growin' bro!

 

[HidingInTheHaze]

if you are growing tomato's they might now be too big a deal, if you are growing sticky MJ you will be having fun picking them off your buds when you go to trim.

 

[sir alex]

hi ive hap these pests in the past and was determined not to have the this time round and treated my coco about 4 times in veg a 1 time at the start of flowering....and guess what ive failed am 6 weeks in and the other day when I watered I noticed tons of the fooking lavae in the pots the twats are back....does any one know what I can do seen as am 6wks in flower????please most are coming down in 2wks but I have some satis that wont be

 

[ozzieAI]

drench your soil with a pure neem oil mix 5ml/litre 2-3 watering over 2 week period and then add neem cake to the top layer of your medium. this will get rid of the ones you have now and stop them from returning

 

[habeeb]

They can be a problem if a huge infestation of larvae pops up. Thankfully all you have to do is cover the topsoil in a 1-2 inch thick layer of fine sand and they will never be able to reproduce again. Quick, cheap and easy. Bye bye gnats.

haha, then they go to the bottom of the pot where is there any drainage hole or any side holes..


as I said, you need to tackle this as a project.

sticky traps / cups of water
a Bti and or nematodes
you can vacuum them up
bare bulb



the more the better to rid them.. one left for the next crop and it starts all again...

 

[Ganjohn420]

If you have a tube of tanglefoot or other sticky goop, you can make your own sticky traps. Go to the paint dept of a big hardware outlet and collect some bright yellow paint color sample cards. Then coat them with a thin layer of sticky.

This is a great idea i'll be able to put a few traps on each container and it will be cost effective

if you think you can ignore them, do so, then get back to let us know.

spinosad, DE, and mosquito dunks...these are your tools.

spinosad to kill flyers and adolescents, DE to desicate larvae, and mosquito dunks to keep them down.

multi-pronged attack works best.

(spinosad can do it all in pretty short order, the diatomaceous earth was more of a subjective remedy, and mosquito dunks will work alone but takes about a week).

good growin' bro!

Thanks man, i'm kind of upset I didn't get on this earlier I should have trusted my gut

drench your soil with a pure neem oil mix 5ml/litre 2-3 watering over 2 week period and then add neem cake to the top layer of your medium. this will get rid of the ones you have now and stop them from returning

Will this also work with expanded clay?

sticky traps / cups of water
a Bti and or nematodes
you can vacuum them up
bare bulb



the more the better to rid them.. one left for the next crop and it starts all again...

What do you mean by cups of water? Should i place the traps near cups of water?

 

[dank.frank]

Rule number 2,730 - don't listen to the hydro store guy. Listen to ICm.

Great tips and advice given in this thread. NEVER let some sort of garden pest continue to gain a foothold in your space...

Medicine...if it is to be called such...should come from an adequate environment...



dank.Frank

 

[ozzieAI]

Rule number 2,730

thought it would have been higher up the food chain than that....

 

[RonSmooth]

I would say that out of the detrimental insects that can infest your grow room, fungus gnats are one of the "best"problems to have.

Thats not to say they can't present problems just that I would rather have gnats than mites, aphids or thrips.

I can never get rid of them 100%. Ill always see one or two adults flying around here and there or I'll have a few stuck on my sticky traps. I have never seen any larvae though.

I used diatomaceous earth in soil and use it around my grow room. That seems to keep bugs to a minimum. I have switched to coco and while I occasionally see adults, I haven't had to treat with any kind of product.

Keeping the top of your medium dry or covered in a layer of sand or clay pebbles helps prevent them from getting in there to lay eggs. The adults arent very bright as far as insects go and can easily be caught in sticky traps or swatted.

And regarding the post that said you would be picking them off buds: They don't feed on the plants, the larvae only feed on roots. When they become adults they grow wings and fly away (to reproduce and lay more eggs in soil)

 

[EclipseFour20]

My post from another thread https://www.icmag.com/ic/showpost.php?p=5859785&postcount=32

....adding Mosquito Bits (not DUNKS) to your soil, bacteria brew, or even as a "top dressing" does work. Adding yellow sticky cards and observing the number of gnats is a nice measuring tool...since I count only 4-10 gnats per card (4 weeks)--I know I am OK. (My next door neighbor over waters her outdoor plants...and I assume that is the primary source of fungus gnats).

Sorry Lola, but dunks don't work. They only slow down the infestation. The time wasted messing around with dunks just prolongs the problem and reduces yield. Same thing with Gnatrol. You end up with a resistant gnat thats even harder to eradicate. What worked best for me was to spray the rootball directly with pyrethium (FoxFarm's Bug Be Gone). The plant pulls it up thru the roots for a systemic effect.

Death to the f'ing gnat hord!!

Let me clear up something--you are 100% correct that there have been reported incidents of critters developing a resistance to the active ingredient in Gnatrol, Mosquito Dunks/Bits--bacillus thuringiensis israelensis (BTI). But if we understand WHEN to use BTI, your rate of success in battling fungus gnats and your pocket book will both improve.

First--here is the Fungus Gnat lifecycle...

The Mode of Action for BTI is "mid-gut membrane disruptor" (no chems) and is most effective against the young first instar larvae, which at the 4 o'clock position in the above pic. The bacteria must be ingested by the larva, after which a toxic protein crystal is released into the insect's gut. Larvae stop feeding and die.

Fungus gnats life cycle is 20-28 days and as you can see, BTI is effective only 2-3 of those days. Huge draw back of Gnatrol is its short effective life of 48 hours, whereas Mosquito Bits/Dunks are constantly releasing BTI as moisture dissolves the carrier--which can take days/weeks.

Strategic use of BTI is the key to success...as there are only a few days of the gnats life when it will work!

Hope this helps!

BTW...for a "soil critter spray" consider this recipe--that will seriously knock down the soil dwellers...but fair warning, if you overspray--it will be white and look like snow on Christmas Morning.

1 gal water
8 oz of Fossil Shell Flour (foodgrade DE)
30 ml Neem Oil
30 ml Riptide (pyrethrin+pbo)

Constant shaking and spray the soil surface liberally! The Fossil Shell Flour acts as both a carrier for the Neem & Riptide...and the dried diatoms act as a "grinder" of sorts and shreds the wings/legs of gnats.

Tip: Emulsify the Neem Oil: Mason jar half filled with water + Neem Oil + Riptide....seal, and shake like a mutha. Then add water to equal 1 gallon.

The attached pdf is a research by Ray Cloyd that concluded, "incorporating (top dusting) DE into commercially available growing medium may not be beneficial to greenhouse producers."

Are Fungus Gnats the worst? No. Do the affect harvest quality and yield? Yes. Do people find dead gnats in their buds? Yes. Do people like finding dead gnats in their buds? No.

Cheers!

 

[Ganjohn420]

I would say that out of the detrimental insects that can infest your grow room, fungus gnats are one of the "best"problems to have.

You're definitely right i'm grateful to only have the gnats and not mites, very grateful!! They are some dumbass insects though, I think the post about them being stuck in the buds comes from the fact that they are dumb as hell and often find themselves in sticky situations. I've had to pick a few out already, dont need to be smokin gnats

My post from another thread https://www.icmag.com/ic/showpost.php?p=5859785&postcount=32
BTW...for a "soil critter spray" consider this recipe--that will seriously knock down the soil dwellers...but fair warning, if you overspray--it will be white and look like snow on Christmas Morning.

1 gal water
8 oz of Fossil Shell Flour (foodgrade DE)
30 ml Neem Oil
30 ml Riptide (pyrethrin+pbo)

Constant shaking and spray the soil surface liberally! The Fossil Shell Flour acts as both a carrier for the Neem & Riptide...and the dried diatoms act as a "grinder" of sorts and shreds the wings/legs of gnats.

Tip: Emulsify the Neem Oil: Mason jar half filled with water + Neem Oil + Riptide....seal, and shake like a mutha. Then add water to equal 1 gallon.

[/I]The attached pdf is a research by Ray Cloyd that concluded, "incorporating (top dusting) DE into commercially available growing medium may not be beneficial to greenhouse producers."

Are Fungus Gnats the worst? No. Do the affect harvest quality and yield? Yes. Do people find dead gnats in their buds? Yes. Do people like finding dead gnats in their buds? No.

Cheers!

Thanks for the info Eclipse it's great! I keep wondering do these methods work on Expanded Clay as well as soil?? Can I spray with the recipe above or should I try attacking them from the water?