Fungus Gnats - A danger for Hydro?

[mokel]

Heya,
had some Fungus Gnats (hadn't known their english name until 5 minutes ago) for several month on my average pot plants, they're starting to loose the war, as their numbers are dwindling but the fight is still on.

Now I've encountered a single, winged gnat inside my grow tent (i presume it entered when i opened the tent) and i'm starting to wonder, whether they can survive and reproduce in hydroponic systems and i should get some bacillus thuringiensis as those nematodes i'm using for my normal pot plants are in need of soil to live and work propperly or if i can ignore the gnats as they can't get a proper foothold and thus pose no real threat to hydroponics ...

 

[GrowInTheDark]

I don't believe you would have any issues with Hydro as Fungus gnats lay their eggs in moist top soil and they feed on the algae and fungus in the soil. The adults don't normally harm a plant but, they do carry diseases that are fatal to plants. but breeding wise I wouldn't worry about them in your Hydro system. It would be kind of funny to see them trying to swim around,

 

[Faic]

Mokel, already answered in your grow thread, but this is for anyone else dealing with gnats too. Obviously if they're coming from houseplants, treat those first, then worry about your weed.

For your plants in soil in pots, to get rid of the gnats, douse the soil with 3% h202, this will kill the larve. Cover the soil with a 1/4 inch of sand or so, and don't forget the drain holes. If you can't set the pot into a pan of sand to cover the holes, pile the sand over them. When you water, be sure to pile the sand back up, because the overflow will expose soil. The sand stops the gnats from laying more eggs, so all you have to do now is not drink any gnats that end up in your coffee till they all die out. Problem solved, and gnat free coffee in about 2-3 weeks depending on your aim, but that's usually the life cycle of the gnats as I understand it.

Once you've got the gnats in your houseplants delt with, time to turn to your girls. Do the same, but forget the sand because you're in hydro. You just want to kill any larve and eggs in your root ball (since I don't think they can actually breed in hydroton). Just rinse the hydroton and rootball with some h202 and feed normally at your res change.

You actually may not have to do anything with your weed, since you're already feeding a bacillus, maybe the gnats are looking for a new pad because all the houseplants are overcrowded?

Gnats in hydro would cause the same problems to a lesser degree than soil. Basically the larve will eat your roots and muck with your girl, and get stuck on the trichomes. A bad infestation in soil is a problem, and can easily get out of hand quickly. Hydro I'd see as still the same threat, but progression would be at a much slower pace.

And Growinthedark, I would strongly suggest you support your statement of 'gnats carry diseases that are fatal to plants' with some specifics, or it's just psudoscience hype.

 

[mokel]

as those adult gnats are able to fly, they can carry diseases from an infected plant to a healthy one and thus spread diseases, like any other fly and as they like rotting material, they're bound to encounter different strains of fungi, pythium for example, and spread those (that's why they called fungus gnats in eng. as far as i know).

i found a re-infested pot plant and used tea tree oil as addition for watering, now those are the only plants with humid soil but the remaining gnats are going to land on that but before they even touch the surface they dart away again .... in their desperation they're landing on totally dried out cacti and money plants (crassula ovata) but won't know what to do there, maybe i should have asked my granddad first

as most of my plants are able to sustain several month of dry periods, seems i'm going antiseptic with tea tree oil and then go for an prolonged dry period and going for bacillus for those that are in need of a regular water schedule.

h2o2 is hard to get by over here and expensive, furthermore last time i tried it it worked for a short period then the problems came back tenfold, but i keep that in mind as a last resort.

 

[Faic]

Oh wow bummer, h202 is like in every dime store here. Go around the plants with a vacuum too.

 

[mokel]

good idea, now i'm rid of those that emerged from the re-infected pot plant without any plan where to go now
got my living room for myself again, hope it stays that way .... going around and shaking my plants every hour still, to see if the gnats accumulate anywhere and try to make a new home but nothing till now

 

[mokel]

got some more fungus gnats, they're trying to plant their eggs in the only humid soil they can find, the tea tree oil treated plant but those little buggers don't dare to go near it, you can see like 10 of them trying to land on the soil, but something is not right and they take a sharp turn and then land on the pot where i crushed them, some tried to get from below, but again, wet tea tree oil soaked soil and no go, seems like they absolutely hate that stuff it's amazing (at the moment, hope it stays that way).
rest of my pot plants are bone dry, seems they're in a pinch right now, will see whats happening the next days


edit:
just as a hint, tea tree oil has a really strong scent, i would guess flavor too so i won't recommend usage on plants near harvest time as i think it'll affect the taste and i'm not sure that tea tree would add to a nice flavor .... plus due it's broad-spectrum anti-microbial and anti-fungal effects it'll kill like everything in a living rez

 

[rillos]

I've always had a few around since I use my basement. I'm a hydro grower and since my tub is covered they can't get to any roots and a few sticky strips hanging just to make you feel better. This is truly one of the benefits of hydro.

 

[Cultivator]

yes gnats can affect hydro. they lay eggs in the root ball. it can be a big problem if it gets out of hand. But using h2o2 will def help get rid of the problem. and use sticky traps also.

 

[rillos]

yes gnats can affect hydro. they lay eggs in the root ball. it can be a big problem if it gets out of hand. But using h2o2 will def help get rid of the problem. and use sticky traps also.

I have not every heard or seen gnats getting to the root ball in hydro. can you explain how they would manage this.

 

[Cultivator]

i dont know how they manage this but it happens as ive had it happen to me 3 times i can remember. and they cause alot of damage.

 

[Faic]

I have not every heard or seen gnats getting to the root ball in hydro. can you explain how they would manage this.

Little tiny scuba gear. The problem they do have is getting their tanks refilled, because most drown trying to swim down to the airstone where the pressure is high enough to refill the tanks.

 

[rillos]

i dont know how they manage this but it happens as ive had it happen to me 3 times i can remember. and they cause alot of damage.

I'm not sure about your set-up, but are you saying that they can in water because that's where I keep my plant's root ball and I really need to find out about this.

 

[Faic]

Well, I never got gnats in my buckets, and I had buckets right next to two infested pots of soil. I would think it would go something like this:
Gnats lay eggs in soil (probably anything closely resembling soil they want, like the slimy root-rot covered top of your root ball above your hydro res). So they lay, hatch, feed, repeat in the upper quarter of your root ball that is never submerged.

As a preventative measure I bathed my root ball in h202 wash, then just changed the res to get the bacillus back. I do periodic flushes with flora-kleen every couple of weeks too and try to wash the scum off my roots (my res temps are still too high @73f so I'm always borderline root-rot :/ ).

 

[rillos]

Well, I never got gnats in my buckets, and I had buckets right next to two infested pots of soil. I would think it would go something like this:
Gnats lay eggs in soil (probably anything closely resembling soil they want, like the slimy root-rot covered top of your root ball above your hydro res). So they lay, hatch, feed, repeat in the upper quarter of your root ball that is never submerged.

As a preventative measure I bathed my root ball in h202 wash, then just changed the res to get the bacillus back. I do periodic flushes with flora-kleen every couple of weeks too and try to wash the scum off my roots (my res temps are still too high @73f so I'm always borderline root-rot :/ ).

Something doesn't seem right. Are you saying your root ball was exposed outside the net pot which is supposed to be covered in clay pellets?

 

[Faic]

Well, the last time she exposed her root ball out of the net pot, it caused a huge accident and miles of backup. The fuzz said to not let her do that anymore or else, so I don't.

But there should be 1/2-1 inch between the bottom of the netpot and your res surface, you don't have the netpot in the res, the gnats use the scum in this 'dry' space, or further up in the hydoton to lay their eggs.

The gnats aren't laying the eggs on or in the hydroton, unless there's something growing on/in the hydroton they see as food right? Leaves only the decaying stuff covering your roots, that isn't sumberged, if you're not talking scuba gnats.

So a bath of h202 wipes out the larve, vacuum up the adults, and repeat as needed.

Simple deduction my good fellow.

If you've done all this and still have a gnat infestation, then the only possibility is, scuba gnats. You'll have to get into the CMDF facilities and get a vehicle of some sort, and destroy them one by one.

 

[Cultivator]

they live in roots growing in the hydroton. also the larger the net pot the more space they have to live and feed above water. if u have a flood and drain system there is only water in the plants for an hour per day or so and i had 2 large infestations in this type of system. its easliy fixed with h2o2 if its caught early. but in large rooms sometimes its not easy to spot right away. if you only have a small system and are monitoring it often then its easier to spot and treat early.