Fungus Gnats Solutions???

[ball23]

We had a big issue with Fungus Gnats a few weeks before we harvested last crop. After harvest we tore the room apart, cleaned, and put it back together. For the first week or so we didn't see anything and now all of a sudden they seem to be back and back in some force. How can we get rid of these things? 2 bombs have been let off and an organic pesticide was used but the issue seems to still persist. If anyone has any ideas they would be GREATLY GREATLY appreciatted.

Thanks Everyone
ball23

 

[Dr. Detroit]

What is your growing medium?

If you're into soil or soil-less, then I like to use predatory nematodes. Added to the soil they're voracious hunters of gnat larvae. I also put a half-inch sand barrier (light colored) over the top to reduce any direct soil-insect contact, and as a side benefit the sand is fairly reflective.

Some flypaper helps too, if for nothing else but to keep a census of gnats.

 

[mrbong73]

If you guys are in soil and can find it. You should try Neem seed meal. I had crazy fungus gnats on my last run and top dressed about 1/4 cup for each plant and made a tea using 1/2 cup per gallon.
Also put the yellow sticky traps for the fliers.
All clear after a couple days.

mrb
edit: also the neem seed meal is 5-1-2 and has loads of other good stuff.

 

[motherlode]

azamax (neem extract) drench every 5 days x 3 will take care of the larvae

to take care of the flies

clean up the bottoms of the plants at least a foot from the tops of the pots

get a fan blowing over the pots - sticky traps and spray azamax every 3 days or so while in veg

should knock them down bigtime and the sand on top is great - the fies cant just dive bomb into your medium that way

a few gnats is no big deal - I always get them here in summer

 

[Carson]

What is your growing medium?

If you're into soil or soil-less, then I like to use predatory nematodes. Added to the soil they're voracious hunters of gnat larvae.

+1
worked for me.

 

[Rootbound]

Instead of sand I use 1/2"- 1" of perlite on top of my soil or coco. Works great and I get to reuse the perlite each run. RB

 

[OGONLY]

I'm in coco and have had great success using Gnatrol whenever I see larvae in the medium or an outbreak of adults. If you have adults you pretty much know there are larvae in your medium.

In order to make the Gnatrol go a long way I water with gallon bottles rather than mix Gnatrol (powder, its a bacteria that parylizes the larvae's gut soit can't eat and thus dies) into a reservoir. Then just pour over medium and larvae are done. I use the yellow sticky traps to get the adults. Last run I had maybe 25 total gnats. Went weeks sometimes without seeing them.

I bought it on Ebay I think for $50. Got like 2 zip lock sandwich bags full. Split it with my buddy and still have most of it left 6 months later. Absolutley worth the money...

 

[Dr. Detroit]

I've found that cheap paving sand works best. I tried horticultural, flushed, beach, etc., but the paving sand has the best qualities: highly reflective, irregular sized bits of aggregate (tighter compaction), affordable, and easily obtainable.

I'd try to avoid perlite and vermiculite on the surface. I used to use both and had a respirator when I was mixing my soils because they're dangerous when inhaled. Now I prefer pumice in their place as an aerator, the benefit being the trace elements and natural source and the drawback being mainly that it's much heavier.

 

[wonka]

this has worked for me (http://www.gardensalive.com/product.asp?pn=3440&bhcd2=1263415380) and used yellow traps for adults!!!

w.wonka

 

[Capulator]

I just watered my plants last week with an EWC tea to kill my brown algae. I had a few fungus gnats... I wasnt even tryimg to get rid of them, but had them, and now I dont. I will post the formula for you when I get a chance.

It works.

 

[Seamaiden]

I've found that cheap paving sand works best. I tried horticultural, flushed, beach, etc., but the paving sand has the best qualities: highly reflective, irregular sized bits of aggregate (tighter compaction), affordable, and easily obtainable.

That's because of the base material of the sand, most likely. In other words, the beach sand is likely calcareous in composition (a bit of vinegar will tell you immediately), whereas the paving sand was likely silicaceous. Completely unrelated to note, you cannot use silicaceous sands when rearing juvenile sharks as it is SO abrasive it abrades their skin to the point of infection and death. Calcareous sands only.


I'm wondering if I should even say what I want to say, so right now I just won't and see what comes of it. I will say this much--when all I was dealing with were fungus gnats they were incredibly easy to control by simply putting sand on top of the pots.

 

[Dr. Detroit]

That's because of the base material of the sand, most likely. In other words, the beach sand is likely calcareous in composition (a bit of vinegar will tell you immediately), whereas the paving sand was likely silicaceous. Completely unrelated to note, you cannot use silicaceous sands when rearing juvenile sharks as it is SO abrasive it abrades their skin to the point of infection and death. Calcareous sands only.


I'm wondering if I should even say what I want to say, so right now I just won't and see what comes of it. I will say this much--when all I was dealing with were fungus gnats they were incredibly easy to control by simply putting sand on top of the pots.

Never thought about the differences in sand composition. Good point there.

I still remember being on a beautiful white sand beach once and being told that they're the result of parrotfish chomping on coral. Millions of years of pebble poops built up. Why someone would tell me that, I still have no idea...

 

[tattoojim]

Never thought about the differences in sand composition. Good point there.

I still remember being on a beautiful white sand beach once and being told that they're the result of parrotfish chomping on coral. Millions of years of pebble poops built up. Why someone would tell me that, I still have no idea...

did i read that correctly,the type of sand you use matters? man i hope that it is ok to use play sand..

 

[Seamaiden]

The type of sand you use will have an effect on the plants, IMO. Calcareous sand means you need to be careful about adding yet more forms of calcium, for instance. Silicaceous sand isn't very easily dissolved at all, so most of it remains in an inert state in or on the media, so for this application it is what I prefer. When I go sand shopping I take a small vial of vinegar with me to test.

Never thought about the differences in sand composition. Good point there.

I still remember being on a beautiful white sand beach once and being told that they're the result of parrotfish chomping on coral. Millions of years of pebble poops built up. Why someone would tell me that, I still have no idea...

Because everybody poops and poop is what makes the world go 'round? It's more than parrotfish. If you've ever been diving in tropical locations you'll see other fishes pooping sand, too, but I would have to guess that parrotfish make the largest contribution. They're also very tasty eating.

That guess thrown out, for me it's absolutely fascinating that the repeated small actions of fish (probably more on a timeline akin to thousands of years, as millions of years means that geological activity has to be factored in) can equal huge stretches of white coral sand beaches. Rather like stromatolites and oxygen.

 

[SSHZ]

I've had those pesky little buggers in the past and Azamax work beter than anything else but a multi level attack works best:

1. yellow, sticky traps for for the flying adults

2. Azamax drench of the soil

3. Azamax spraying down the plants.

I would continue this procedure into the next crop or two for security. Then I use it every so often just in case. No problems since.....

 

[sjstylz408]

I've had those pesky little buggers in the past and Azamax work beter than anything else but a multi level attack works best:

1. yellow, sticky traps for for the flying adults

2. Azamax drench of the soil

3. Azamax spraying down the plants.

I would continue this procedure into the next crop or two for security. Then I use it every so often just in case. No problems since.....

How long do you spray or feed the plants with azamax?

 

[sjstylz408]

so wait.... What type of sand do i use. Defently intresting and seems like a simple yet effective

 

[Seamaiden]

I prefer any sand that's silicate in composition for growing. That way I not only have better control of Ca/Mg (and whatever else might be present in that particular batch of calcareous sand) but I also know that, on a microscopic level, the silicate sand is MUCH more uncomfortable for small things to crawl through.

Take a small cup of vinegar with you, pour a tiny bit on the sand. If it bubbles, it's definitely calcareous. If you have a loupe or other good magnifier then take a look at the sand particles themselves, if they're sharp-sided then it may be silicate composition. Unfortunately, I don't know of a definitive test for silicate composition, only calcareous.

 

[MIway]

I've had those pesky little buggers in the past and Azamax work beter than anything else but a multi level attack works best:

1. yellow, sticky traps for for the flying adults

2. Azamax drench of the soil

3. Azamax spraying down the plants.

I would continue this procedure into the next crop or two for security. Then I use it every so often just in case. No problems since.....

Think this might indeed work... the need drench & spraying of the pots. Was doing something similar to knock out soil mites... had a fungus gnat pop starting in a room as well... no more gnats, though had the mites still... also got in a bag of springtails (brought all my bugs in that bag actually) & they were gone too. Fig'n it was the Azatrol that I was using... both the gnats & the springtails were gone over a week or two... also was spraying the tops & holes on the pots with pyrethrum.


Just to note... pretty darn sure the Imid drenches kill off the gnats over the coarse of a week as well. The Bayer Complete is what was used... and they died off... also w sticky traps to contain the adult flyers, but the larvae sure as heck died off over a few days.


Problem I've noticed w the gnats is that they go in through the varying drain holes in the pots, so you've almost got to get something into the medium itself to fully eradicate.

Even had this guys house where they never cleaned their toilets... that actually harbored a small colony of gnats.

Generally, the gnats seem to bring in a disco ball & their Gloria Gaynor on vinyl, so... ;-)

 

[Kobe24]

Mosquito Dunks work amazing....take the whole pack and crush them into a 5 gallon bucket....a few doses of that concetrated mix with some follow up of Neemix 4.5 aka azatrol should eliminate them for good...

Using some Pond Enzymes to eat up any crap the larvave would eat helps too