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spasm666
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Fungus gnats 2
#28320039 - 05/15/23 12:10 AM (8 months, 10 days ago) |
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It seems that for the first time I will be having trouble with the dreaded fungus gnats. They're not yet in vast numbers but I expect them to increase exponentially.
I've read earlier that it's super hard to get rid of them once you got them, and you'd need to bomb the place with chemicals to fight them. Obviously that is very hard to execute as I'm running production constantly and cannot stop the running train. Any suggestions? I'm having of course a lot of the yellow fly tape and some electric traps with UV lights but that will not end the problem I suppose.
Also, the important question is, what damage they do? I mean do they cause any harm in the FC? Colonized bags are quite resistant to outside threats as they are, well, colonized already. Or is it mainly an issue with the incubation? My incubation is about 99% sealed and air is run through a filter that won't let the bastards through. But of course there's that 1%. Oh and I don't make my own spawn so that's not a threat area.
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Harry Manbach
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Re: Fungus gnats [Re: spasm666]
#28320096 - 05/15/23 03:34 AM (8 months, 10 days ago) |
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Idk about bombing the place with chemicals, but definitely start with inspecting and tossing ANY bags you see them on! They'll wick the life right out of fresh pinsets and fruits making them look like hell. All the while, usually working their way past the fruits to lay their eggs in the substrate.
As far as prevention I've found pyrethrin products work quite well, with relatively low toxicity/risk. Specifically I've used a product called Garden Safe, found at Tractor Supply, I think it was like $10.
I'll avoid spraying until I see some gnats, but when trying to recover from an infestation I'll toss the infected bags, spray all bags not fruiting with a quick mist, and spray down the walls and any new bags that go in for the next few days.
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Stromrider
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I have sticky yellow sheets hanging all over the place. I also have one of those stihl backpack foggers. It's like a backpack blower but it has a tank to hold liquid and sprays a massive fog. I alternate fogging bifenthrin and permethin every 2 weeks for about a acre around my operation. That seems to help a lot plus we have no mosquitos now. It was an $800 investment is the downside
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spasm666
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Wow so they really mess up the fruitbodies. Good to know. I got some weird looking mushrooms from the last harvest but I think it was because I accidentally left my AC to heat mode for the weekend.
Stromrider's backpack spraying sounds quite heavy approach. Wouldn't even thought something like that (and in my case couldn't even do it). You're not messing around I see.
Anyway I think I catched them early, phew. I noticed the gnats on Monday and harvested all on tuesday and removed all the used bags. Then sprayed pyrethrin in the FC (not so heavily on the next weeks harvest which was just starting to pin) and in the work area. Also doubled down on the yellow sticky sheets in the ceiling. Wednesday morning there were just a few in the electric insect trap and today none. And haven't seen a single on flying around either.
How fast the eggs hatch? If they're in the next weeks harvest bags trouble might be not over yet. But so far seems ok.
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the_chosen_one
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Mosquito Dunks https://en.wikipedia.org/wiki/Bacillus_thuringiensis_israelensis About a quarter dunk per gallon of water. Filter for sprayers but otherwise just use the water and let it kill the larvae.
-------------------- "Luck favors the observant." - Workman
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CreonAntigone
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Concentrated neem oil kills on contact and repels them. It kills adults and larvae but likely not eggs so it needs to be reapplied. I have noticed a good reduction in number after spraying with it, but they do keep coming back somewhat so I would suggest looking at the bacteria solution for a permanent fix.
But, a regular spraying of neem oil whenever you find adults - at a concentration of 30% neem oil or more, mixed with water and a bit of castile soap - will help remove them. It is not all that toxic to substrates, either. Soaking in neem will be more likely to completely eliminate them but would risk more potential damage to the mycelium.
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spasm666
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Quote:
the_chosen_one said: Mosquito Dunks https://en.wikipedia.org/wiki/Bacillus_thuringiensis_israelensis About a quarter dunk per gallon of water. Filter for sprayers but otherwise just use the water and let it kill the larvae.
Interesting. So I put the Dunk thing in water and spray the bags with it? Or did I get it wrong? Could them be put straight into the humidifier water reservoir? Can you elaborate the filter thing? I need to filter the Dunk-water first? What kind of filter?
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the_chosen_one
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Yes. Treat anything the larvae can live in post pasteurization.
That would depend on your humidifier. If it's steam.. no. Inline trickle might work, but I've never needed to try it in a humidifier.
Basically I just start the whole thing in a bucket and filter it with a paper towel to get the larger bits out. Otherwise they can plug your sprayer. It will also work by crumbling and sprinkling it onto or into a wet substrate. Even moisture can activate it but I trust water to do the best job.
It'll take a few days to a week or so to break the cycle but once they are gone.. they are gone. It's actually an old cannabis trick from way back but it works for everything. I even water my house plants with it.
edit.. give it a day or two in the water before using.
-------------------- "Luck favors the observant." - Workman
Edited by the_chosen_one (05/19/23 03:46 PM)
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spasm666
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Ok cool, got it. That's pretty straightforward and if it works it seems easy enough.
Can you spray edible stuff with it without residues/issues? Probably not needed for mushroom fruitbodies but I'm growing dozens of trays of microgreens weekly too so I would definitely need to spray those too. The gnats surely likes my microgreens tents (eventhough I'm using a relatively less attractive medium for them (no soil or coir but hemp fibre mats).
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the_chosen_one
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I'd probably lessen the dosage for microgreens a little and watch the pH closely. I've used it for seedlings with little problems but have caught it moving pH with heavier doses. Should be fine otherwise. I use it for my strawberries because I keep them in pots. They don't get sprayed but often get wet with the water. I probably wouldn't spray the greens and just water them with it. The gnat larvae are chewing on the rhizomes so that's where it needs to be.
-------------------- "Luck favors the observant." - Workman
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spasm666
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Perfect. Thank you for the insight. If I spot any gnats monday when I get back, I'll order some dunk.
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spasm666
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Quote:
Harry Manbach said:They'll wick the life right out of fresh pinsets and fruits making them look like hell.
Is this how gnat-infested fruits look like?

Half of my yield this week looked like this. I'm having them gnats again in increased numbers so this might be the reason. BUT could be also co2 issue from tightly packed FC (which I kinda doubt because these uglies don't have long stems) or bacterial contamination (I have orange caps here and there, not losing yield because of that but as a sign it's gotta be noticed). Trying to figure out what the hell is wrong now. Of course I need to start fighting the gnats again, but not sure if this is related.
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Harry Manbach
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Re: Fungus gnats [Re: spasm666]
#28391302 - 07/10/23 12:29 PM (6 months, 16 days ago) |
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Quote:
spasm666 said:
Quote:
Harry Manbach said:They'll wick the life right out of fresh pinsets and fruits making them look like hell.
Is this how gnat-infested fruits look like?

Half of my yield this week looked like this. I'm having them gnats again in increased numbers so this might be the reason. BUT could be also co2 issue from tightly packed FC (which I kinda doubt because these uglies don't have long stems) or bacterial contamination (I have orange caps here and there, not losing yield because of that but as a sign it's gotta be noticed). Trying to figure out what the hell is wrong now. Of course I need to start fighting the gnats again, but not sure if this is related.
Doesn't look like gnat damage.. Or any damage, IMO. Some look slightly over mature, but by your description sounds like a CO2 issue. They may not have leggy stems, but that just might mean you have good air circulation(with higher than normal CO2 levels). Do you have a CO2 meter to gauge actual levels before/after you packed the fruit chamber?
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spasm666
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Okay. Yeah they seem to get over mature before they grow up. Getting reduced yields and the clusters get all flat and ready and curved up right away before they get to normal size.
I do have a good air circulation in that part of the FC. I kinda thought that would deal with the possible co2 issues, but I guess not. In the other end of the FC I got long stems and I know there's less air circulation there. But in that end the fruits look normal, eventhough long-stemmed. I don't quite get it, as there should be no less co2 in that part of the FC than in the other (and if some, mostly the opposite).
No I don't have a co2 meter, haven't got a use for one so far.
How does the gnat damage look like?
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Harry Manbach
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Re: Fungus gnats [Re: spasm666]
#28391373 - 07/10/23 01:57 PM (6 months, 16 days ago) |
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..I think you now have a use for one.
Gnats usually leave fruits brown and shriveled... Usually smelly at times.
If stagnate pockets or elevated CO2 levels aren't your issue (I'd bet that's it tho) it sure would be easy to look at a digital meter, rule it out & adjust from there.
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spasm666
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Yeah I guess I might use one right now. I could of course lessen the bag load in the FC little by little and see where's the optimum. But that would take weeks/months, a meter would tell me right away. Don't wanna spend hundreds for that, any suggestions for a cheaper one? Maybe a handheld unit (as I don't think I'm gonna use it except for situations like this)?
But don't you find it weird that in the part of the FC where there's less air circulation, I get normal fruits but with long stems, and in the part where there's more air circulation, I get these worse looking fruits? All in the same FC after all.
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Harry Manbach
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Re: Fungus gnats [Re: spasm666]
#28392207 - 07/11/23 08:24 AM (6 months, 15 days ago) |
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I spent $120 on mine a couple of years ago and it's been on/in the grow room since. Although I can't find the exact model anymore, a quick search on Amazon brings up several meters around that price or cheaper.
I don't find it all that odd that as you pack in your space, limiting airflow and circulation, creating micro climates, that fruits are responding differently in different areas. The only way to be sure is with the proper equipment.
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spasm666
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Yeah. I guess, even once, I'll make things easier for me and order a meter. What was the good/bad ppm range?
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Harry Manbach
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Re: Fungus gnats [Re: spasm666]
#28393474 - 07/12/23 12:09 PM (6 months, 14 days ago) |
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Well.. The lower the better. But it will depend on your situation, for me 600-800 is about the best I can get during summer/winter months when the windows are closed. I'll panic when it gets up to 1100-1200 and pump fresh outside air in the air conditioning room around the grow. You'll just have to get familiar with your ambient levels, grow levels and where you need to be at with your fruits looking the way you want.
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spasm666
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Yeah, this is the way. Thanks. Ordered a meter.
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