Potential 'Fungus Gnat' issue - Diatomaceous Earth?

Tact

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Pertinent info:

FFOF/LW soil, basement grow, low RH in the room due to dehumidifier (20%-50%, depending if its off or on for hours at a time, though I keep it on at night to raise temps slightly). I suspect if there is gnats, they came in the soil medium itself. This is my first grow and I have not really watered the seedlings yet, I germed 13 seeds and all 13 seedlings broke ground, one is struggling though with its 'seed helmet', as of today the seedlings are 5+ days old. When I mixed the soil together I poured 2 gallons of pH balanced water into the mixture and mixed it thoroughly, then I put the soil in each of the 13 pots. The seeds were germed in 6.5 pH soaked/then squegeed root plugs (from Worms Way used for clones/seedlings, I believe it is ground bark, suggest by DS by way of THG method), and the plugs were put directly in the mixture of 50/50 FFOF/LW. As the seeds germed in the plugs/soil I put freezer zip-lock bags over each pot to keep the RH high in a greenhouse dome type environment, after they all sprouted I removed the bags, maybe 3 days ago. Since that time I had only 'misted' the top of the plants, as the soil was beginning to get very light in color, and I am unsure that 1 bag of FFOF, and 1 bag LW was 'soaked through' using only 2 gallons of water. I fear this misting created an environment for dormant eggs, already in the medium, to hatch. I maybe misted a total of 5 times over 3 days, once, and perhaps most critically an hour before lights out (the first time), since then I had only misted in the morning when the lights flipped on.

Here is what happened, last night I went down to my grow room about 2 hours before the timer flipped off, I was just overlooking the small seedlings, seeing how the one that is struggling to get its 'seed helmet' off was doing and taking note of temps/RH while fine-tuning fan speeds etc, when I saw a small, black, winged insect sitting on the rim of one of the pots. I went to smash it with my fingers and it flew off, I could not tell if it hopped in the soil or took flight away and the room circulation carried it out of sight right away. I came on here and did some research, I saw all the methods Hick and ME gave regarding Gnatrol, sand/perlite/diatomaceous earth on the top layer 2-3" of soil, as well as watering from the bottom. I went back and checked 4 times before lights out and did not see the insect again, so what I did do, and could do at 11 pm last night was mix two clear (dipping sauce sized) dishes, one with lemon-scented dish soap/water, the other with beer, and put them on a piece of white paper in the room. The idea here was that apparently (as discussed in various threads on this forum) the adult gnats are drawn to these mixtures and will get stuck/die in them. I did this as a way to attempt a basic diagnosis if there were more flighted insects, this morning when I went to check on the room I saw nothing in the soap/water and beer liquids. I aerated the soil of all 13 pots with a fork 2-3" beneath the soil, and put the dehumidifier on, which I reserve for night time to raise temps above 70 in the lights off period. The result of having the dehumidifer on so long dropped the RH to 19%, I turned it off since and it climbed back up to 35%. I do have a humidifier if these RH levels need to go higher, humidifier during the day, dehumidifier at night type thing?

There may be some redundancy's in what I wrote, I am just trying to share all the information. The room itself, as well as the whole house was sprayed by a bug-man not even 3 weeks ago.

Still, due to the fact that 1 adult gnat can lay 1000 eggs, and the life-cycle can make it so I would not see more adult gnats for 5 days+, should I preemptively put diatomaceous earth on the top of all the pots AFTER the next watering, which will be tomorrow (1L per pot)? I called my local Worm's Way (hydro store) and the lady said diatomaceous earth is worthless after you water it, and dangerous before you water it (inhalation dust that will circulate in the room). She insisted I water the pots from the bottom, which would mean stagnant water, though I see it is often suggested and actually promotes root growth as they stretch down to the moisture?

So what are your guys thoughts, use the diatomaceous earth and perlite on top (i have perlite FFOF chunky right now), wait and asses the situation? The bug was quite small, and after reviewing the species that HIE I believe put up, it was either a fungus gnat, a thrip, or none of the above. It did not seem to have the long, disgusting looking legs that the FG pictures had, after repeatedly going down and checking the room and literally standing over the soil like a psycho for 20 minutes I can't see a single insect, no movement. Though if that one, whatever insect did lay some eggs, they would not be visually evident anyway, I will pick up some sticky strips to hang for further evidence gathering?

Bleeeeeh.
 

fleshstain

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i think you may be jumping the gun a bit.... i saw a gnat in my cabinet yesterday, killed it, and went on with what i was doing.... that's about all the attention it drew from me at the time.... we also have fruit fly's pop up around here all the time.... i wouldn't let it worry you that much right now....
 

Tact

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So the way to move forward here, sticky strips? Is that about all I can do, to even get a specimen to make sure I know what I am dealing with if anything? Still nothing in the two liquid containers. Room temps 78, RH 35%.
 

Tact

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Well I picked up a Hot Shot No-Pest Strip, that Hick is absolutely not a fan of after researching it in the forum. So the plan for now will be to wait and bust it out if I see some flying critters. Will flying bugs be attracting to those solutions of water/soap and the other of beer? Or is that a pointless way to see if anything is flying around. The Hot Shot strip is apparently quite toxic and shouldn't be used unless absolutely necessary.
 
L

legalize_freedom

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Don't get all freaked out by what you are about to read! I too think you are probably jumping the gun, but I have to tell you about the conversation I had with the owner of one of the hydro stores I use. I had a terrible problem with gnats my last grow, and I didn't really tell anyone, I just was constantly battling them, in FFOF/LW, I was at the hydro store and was checking out a soiless mix that they had just got in, and told the guy I usually use ffof....he right off the bat asked if I had a gnat problem. It seems that at that time there was a batch that was infested, that worked it's way up to the Great Lakes region. After hearing this I posted on here to see if anyone had a problem, and only one other person said that they did. The store owner said that he had contacted FF and they told him the problem was under control. These were not fungus gnats and they did not hurt my crop....just generaly an anoyance. I had already bought my stuff for this grow, so I wasn't going to not use it. I have not had a problem so far a little under a month 1/2. I do see random bugs in there from time to time...but nothing to worry about. If you do have a problem, I finally broke down and bought go gnats I think it was called...or no gnats, it was what worked best for me. One of the problems with running soil, is critters, as long as it's not an infestation, I'd not worry about it. Good Luck!
 

Tact

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Hey LF, while doing research I saw your post and noted it was in October of 09, not even a month ago. As I am in St. Louis, Mo I wonder if I would of gotten the same batch. I got the soil from a local Worm's Way, they stack them in the store on top of one another near the front door. So it was confirmed that it was not an issue with Fungus Gnats, but.. a different specie of gnat or just flying insect? I did a little reading and it other gnats, more then just Fungus Gnats feed on roots as larvae, but wikipedia hardly had great information on it without a specific species. The black-winged fungus gnat could of been what I saw, but who can say, for now I will just have to wait.

hXXp://en.wikipedia.org/wiki/Dark-winged_fungus_gnat
 
L

legalize_freedom

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yeah the post was put up when I talked to the guy....lets see...this current grow started Oct 20,th...sooo I think I harvested the grow before around the middle of sept. I know I veg'd that grow for 2 months , and 2 mo flowering so that bad batch would have bought around around mid May...I'm guessing. The batch I am using now has been in long enough that I think I would have seen soething by now, but I also have about an inch or so of perlite on as a top dressing to. Whatever kind of bugs they were, they did not hurt my yeild at all I got .8 g/watt out of soil...thats the best I've done as of yet indoors.

I think it was gnat of some sort, or a fruit fly...but I would say more like a gnat. Like I said this batch I have now is not bad. But I guess it could be possable that you got part of that bad batch...I dunno. Trust me if you had the bad batch you will know soon, because they will be everywhere when you go into your grow! I mean I had sticky strips up that I had to replace because there was no more sticky part left...it was BAD!
 

Raidernation

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whats the word on this diatomaceous earth?I just mixed some in a spray bottle and sprayed my flowering plants and my clones with it because of mites.Anybody use this for mites?
 
L

legalize_freedom

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I'm not sure how effective that would be with mites...you would probably have better luck with mites by using a horticultural oil...like neem oil. I think the DE is more used for hard shelled insects, but don't quote me on this, and definately do some more research, as I've not had a mite problem to deal with ....knock on wood!
 

Raidernation

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thanks LF i just looked around and see that people use this for spider mites but i have a problem now it looks like its drying out the pistils it looks burnt a little, not like straight hairs like how it was before, i didnt turn lights out but i havnt really thought it through but DE's purpose is to dry out things **** man
 

Raidernation

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MindzEye said:
DE is used for covering soil for soil dwelling pests... Spraying it on a plant isnt going to do anything... What DE does is when a hard shell insect comes in contact with it the DE cuts them the bug later dies of dehydration from loosing fluid rapidly... To effectively use DE you use a 1-2 inch layer over the top of soil... This isnt going to do much for mites..

For mites use some Avid, or Azatrol
i just read and also saw pictures of people spraying DE on leaves and getting rid of spider mites
 
M

mountain man

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You positively have THRIPS. They have 3 different life cycles and are very difficult to get rid of. Do some research, it will all make since then. Nymph, sub-aduly and adult (what you saw flying) I will tell you Monterey Garden insect spray (Spinosad is the active ingre. )at 3-5 days apart for 3 treatments works. But then use another type pyrthuim type spray as an alternate.
Leaves curl inward. Rattle some foliage and you will see one fly. Yellow sticky or BLUE work for fliers. Pots have to be sprayed too.
Never into flower tho guys.............
 
L

legalize_freedom

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Raidernation said:
i just read and also saw pictures of people spraying DE on leaves and getting rid of spider mites

Just because you see other people doing it, doesn't mean it's right. Mindzeye is trying to help you, take his advice...he is a knowledgable man, who has dealt with these problems.

I don't understand why some come here and ask for help, and then argue about the response that they get...if you already knew that you were going to do whatever you wanted regardless of the advice, ...why bother asking the question? Good luck with your problem...your going to need it if your not willing to listen to someone who has been through it.
 

Raidernation

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Im sorry if i came across that way but i have already sprayed it on my plants.
 

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