Ravaged by fungus gnats???

I started noticing gnats a while ago but didn't worry about them too much as it didn't look like they were actually damaging my plants. I was getting a lot of stunted growth but didn't connect the two. After a while the gnats got thicker and my plants started turning yellow, drying up and dying. Long story short, I read up a little on the gnats and went to war with them. First of all I keep two rooms. I've got one room for vegetative growth with a couple of t5s and a flowering room with some bigger lights and better fans. I've seen a few gnats in the flowering room but most of them have been in the vegetative room. So after a little research i put out a bunch of sticky traps and I watered all the plant in the v room with a solution of 4 parts water and one part hydrogen peroxide while I ordered and waited for nematodes and mosquito dunks. Three or four days later I put 5 million nematodes in about 7 gallons of water and watered everything in both rooms. I repeated that about 3 days later. In another 3 days I still wasn't seeing any progress so I crumbled up about a half dozen mosquito dunks and spread the dust over the soil in all the pots. I put a couple more dunks in a five gallon bucket and have been watering the plants from that ever since. About 3 days after that (2 or 3 days ago) I began noticing a big drop off in the number of gnats. Now I'm only seeing one or two when I water the plants. When I started out I had nearly 150 plants ranging from a week to probably two and a half months old in the v room. I've probably lost two thirds of them and the ones that are left range from healthy to very sick looking. They still seem to be dying off albeit at a much slower pace. I'm wondering if this is all due to the gnats or am I dealing with another problem in addition to the gnats? Any help or advice would be greatly appreciated. I will put up a couple pics. Thanx.

They will hit the roots first, before they emerge from soil, imo. :joint1:

The sticky traps work great for the flying gnats, for the larvae in the soil you'll need to let the soil dry out completely, to the point where it looks like your ladies are very sad and droopy. Gnats love moist soil. This could be part of your problem as to why they aren't dying as fast. Another thing you can do is purchase a pound or two of (Sterile) Sand, and put about 1/2" to 1" on top of your soil, I would do this about 3 days after watering. The sand is too heavy and dense for the larvae to crawl out. As long as you let your soil dry out completely between watering, you'll notice more and more dead gnats.

I also use a shot glass or small lid (shallow), pour a small amount of wine or beer in the lid, set it at the base of the plant or on top of the soil. Come back the next day and you have a glass/lid full of drunken dead gnats.

Also, look up a drench solution called "Azamax". It's simple, easy, and effective. Just add the specified amount of solution to water and drench your soil with about a 1/4 run-off. Repeat this process once a week or until soil is completely dried out, for about 3 weeks. This product also fights mites/insects of all kinds as well as fungus, and mold!

I definitely appreciate the input but I think I've pretty much got the bugs under control. Being that I'm down to almost zero gnats I'm guessing that the larvae have been mostly dead for a week or so now. What I'm asking is whether or not one would expect their plants to continue dying off this long? My plants are still continuing to turn yellow, dry up and die (although, at a much slower pace) and I'm starting to wonder if I have another problem in addition to the gnats.

At this point I would repot them all in fresh soil. Get a good look at the root's on the sickest one, probably a sacrificial lamb though. What soil are they in? Did they germinate in that soil?

Actually, I have repotted a few of them. I cleaned them up and put them in water overnight and back into new soil the next day. Four out of five of them look like they're gonna make it. The fifth one is still questionable. They are in Scotts potting soil. Some of them are clones and some are from seeds. I put clones and seedlings into jiffy pellets and then into the soil. Not sure that's the best thing to do but it is how I started my plants years ago when I grew outside.

Sounds like you're well on your way to getting the gnats under control. I'd say that is most of the problem, because even with the gnats dead, you still have root damage which will take a while to heal (if it does), or it could be permanent that causes eventual death. Really depends on how strong the plants/clone strain is and how well they can tolerate the root damage and how quickly they can regrow a (or grow a new) root system.

I had the gnat problem myself and realized it came from buying cheap dirt. Not to say Scott's is cheap.... I really have no idea on that one. I can say that since I popped for the actual miracle grow I have not had this problem. Something about the way they treat their soil. When I ran into this issue, a friend recommended NEEM oil. A little bit in a spray bottle with your regular water goes a very long way. Treat once a week, soaking the soil down with the spray and the gnats were gone completely after 2 treatments.

As for the continuing yellowing/leaves dying that would seem to be a factor of a poor root system. When I'm doing my clones, I put the cutting straight into water and leave them there until they get a nice, thick root system. I was using a rooting hormone to start with, but found out just the water by itself seems to perform about as well. Using just the water like I do may add a few days to the rooting cycle, but I've notice doing it this way seems to work best for me. Just my two cents!

If fungus gnats become a serious problem, that indicates other issues. Namely, your soil is drenched and somewhat anaerobic. Having a few around is no big deal, but as others have pointed out, if the larvae become dense enough in populatipon, they run out of microrhizzae to consume and start eating roots. Bummer. But the fact that this is happening points to other problems, which may persist even after the (current) batch of gnats is knocked down. You MUST have soil that drains easily and does not allow stagnation around the roots. Fungus gnats thrive under those conditions. But those conditions also mess up the transport of nutrients and oxygen into the roost, so the overall problem is compounded. Use the best soil you can find (Foxfarm Ocean Forest may be the best soil I've ever used in terms of drainage and proper water retention) and make sure you water through. Don't allow the holes in the pot bottoms to sit in water. Forgive me if you already know everything I've said, but I deal with fungus gnats in a greenhouse constantly. We use them like the "canary in the coalmine". If we see a lot of them, we know our water/soil situation has a problem.

How long do them in water? Scott's is decent but it is fairly cheap and may be where they came from. I've been doing this for a year now and have probably had the gnats for three months. So it hasn't always been a problem. I'm sold on Nematodes and mosquito dunks and will continue to use both as a preventive measure. I just repotted several plants and a few of them just had NOTHING left for roots. No wonder they're looking so bad.

Yes you indeed had a serious infestation. Once those larvae get a taste for roots they're off to the races. The roots become weaker as the stagnant water suffocates them. Free lunch. Personally I hate all commercial potting soils. There are many threads in this forum dealing with this issue, but if I'm going commercial I will only use the best. Screw cost; you get what you pay for. But in the event that you simply cannot find good soil like Foxfarm, just make sure that you're letting the soil dry out a bit before watering again. At least the top inch or so should be dry, and NO standing water in the lower levels of the rootball. Drainage, drainage, drainage. In nature there is a limitless soil horizon around each plant and water can diffuse away. In a pot things are much more restricted and problematic.

@Chromophore, Thanks, I appreciate any input. The soil I'm using drains fairly well. These things really became a problem when the temperatures and humidity dropped. I'm running a space heater in my veg room and the the soil dries fast. The plants will droop and sag in 36 hours after being watered if they don't get watered again. So they were getting watered about every 24 hours which, I guess, created an optimum environment for the gnats. I'm not sure how to get around that now other than by keeping the pots full of nematodes.

I've been reading up on the best ways to get rid of these little devils as well as 200 other garden pests.

Heterorhabditis Bacteriophora also known as Beneficial Nematodes (Steinernema Feltiae) are microscopic warriors that kill soil borne pests such as flea larvae, spidermites, fungus gnat, weevils, grubs, rootworms, cutworms, and many more. These Nematodes search, find, and kill pests living in the soil. They are extremely effective, and will reproduce and spread to provide you with long lasting organic pest control. Safe for plants, pets, and people. May be applied in a mulch, with garden sprayer or watering can. Unlike other beneficial nematodes, the Steinernema Feltiae only needs to be applied every 12 - 18 months.

It sounds like the best and most natural way to rid the garden of annoying bug type pests.

Has anyone tried this?

The ones I'm using are the Steinernema Feltiae. I've used them along with the mosquito dunks which I crumbled and put in the soil. I also put two dunks in a five gallon bucket and have been using it to water with since. I watered with the nematodes 10 or 11 days ago for the first time and I've pretty much explained above what I've done since and right now I don't see a single gnat flying around anymore. There was practically a cloud of them 10 days ago. So I can't say for sure it was the nematodes or the dunks but both of them together have been extremely effective.

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Originally Posted by Lemuel714

How long do them in water? Scott's is decent but it is fairly cheap and may be where they came from. I've been doing this for a year now and have probably had the gnats for three months. So it hasn't always been a problem. I'm sold on Nematodes and mosquito dunks and will continue to use both as a preventive measure. I just repotted several plants and a few of them just had NOTHING left for roots. No wonder they're looking so bad.

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I'll assume the water question was for me. It varies actually. I have 2 unknown strains, and each one reacted differently. The shorter of the two strains seemed to root pretty quick, I'd say within 7 days, the other, taller one took almost 2 weeks.... that is if I am remembering correctly. There were some other things that seemed to effect how long it took also. When I started with these two clones, for instance, I put them both in clear containers. I'm finding that tends to slow things down because once I figured out the root system needed darkness and added a cloth over the clear container, roots popped with 48 hours. Since then, I've tried a couple other things. I have one that's in a bottle that has been covered with black tape to provide darkness, I have another that is in a colored bottle that provides some shade and some light, and then I tried some straight into soil with rooting hormone. I saw "Saving Grace" once again, and there's a scene in there when they are cloning and they go straight to soil with the rooting hormone. Out of all of these trials, the straight to soil performed the worst, by far. I lost 2 clones in the process and although some of that was due to me not using a humidity dome I'm still finding I like the water only method the best - going that way I have yet to lose anything. Everything I'm doing is for personal use, and I'm more concerned with quality than time or quantity for that matter. Don't get me wrong, I still want a nice harvest but with the crap smoke we have around here, I'd rather have more potent than just more.

Here's a couple of pics of what I have going on. The first two are pictures of the clones, which are in my flower room now. The third pic is of the clone in the colored bottle, and the last pic is the root system starting on the one that is in the bottle with black tape for complete darkness.

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Now, if you look at picture three, you'll see a bunch of white dots on the stem. These are actually the beginnings of the root system, and there are a couple of small roots. Picture number four shows a little of the same, but this time the roots have developed a little more. You can literally see the difference the dark has for root development, even though both are still rooting. These were both put into the water the at the same time, BTW. Picture number four with the small roots is off to a good start. For my personal tastes, the roots are still a little small, so I'll let that stay in the water a couple more days until most of the roots reach about 2" and have a nice, thick root ball.

The clones in pictures number one and two were started this way, and they seem to be doing great. A couple people have advised that I am perhaps keeping them in the veg cycle a little more than needed.... I let them stay in the veg room about a month after they were in soil so they would get nice and tall. They did, with one being around 3 ft and the other closer to 4. I was under the impression that once they hit flower they would stop getting taller and just bud out but alas, that was incorrect, so my flower closet is overflowing atm. Hey, more bud though, right?

Yeah, the question was for you. Thanks for the info. I've been thinking about putting my clones in water for a while now. It looks like it will be a while before I have anything to clone again now though. I had a hermie late last spring that I caught way to late. I was really bummed about it for a while at the time although it didn't turn out to be nearly as devastating as I thought it was going to. It did provide me with a good assortment of seeds. I'm grateful for that now. It looks like you take much larger cuttings than I normally do. I usually put mine in the jiffy pellets and wait till I see roots coming out before I put the whole thing in soil. It has been taking longer and longer for the roots to appear and I've been losing over 50 percent of my clones lately (as opposed to 0 to 1 or 2 percent normally). I assume the gnats are the culprit for that now.

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Originally Posted by Lemuel714

It looks like you take much larger cuttings than I normally do.

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Heh heh, yeah. I seem to have a problem(?) with my plants actually being too big. I related a story in another post about one of the first grows I did where the darned thing got to be about 13 feet tall. At the time, I was all for it thinking, well I do have the space (large walk-in closet), and the more plant the more bud, right? So I bent and twisted that thing all the way around the room until it was just a solid mass of plant covering all four walls. That would have probably been a great harvest had I not gotten over paranoid about all the helicopters flying by and chopped her down too early. I guess that's what I get though for living within 2 miles of an international airport and not performing my due diligence about how FLIR actually works, or the fact that one single plant, no matter how big, is still not worthy of prison time (normally). Oh well, those were different, more prohibitive times.

Since then I've learned about cloning and being able to keep the plants quite a bit shorter. (I'm bordering on close to 5' on the biggest now) Still, when I take the cuttings, I normally lop off a good sized top piece and root that - which helps stunt the height. There's a pretty decent video on YouTube called "I grow chronic". My old roommate gave me a copy of it on DVD and most of what I've learned has come from that, up until I found this site.

As of right now, I'm actually torn between staying with mother-clone and moving to just the auto flowers. Since I don't know what strains I have in mother-clone I'm just having to wait until the first harvest to test things out and see what I want to keep. One plant looks really great, and the other seems to be a great producer although slower growing. I may end up budding out the mothers and cloning from the clones just to keep stock if they are good, or perhaps killing off one of the strains if it under-performs after harvest. The reason I'm torn about going to the auto flowers, is they seem to be much easier to grow and maintain versus the mother-clone process. If I could just put fresh seed into the ground every 90 days or so and come away with enough to last me 90 days with minimal space (no need for veg and flower rooms) and have some killer smoke, that seems like the best way to go. If you're up at 150 clones though, you're probably looking for more than just personal. At any rate, the latest seeds I started were some dark devil and black cream that I ordered from overseas. I was actually quite worried about that whole process since this was the first time I had ever ordered seeds. I was very happy with the way things turned out though. If you're looking to get some great seed stock, it's an option definitely worth considering although I would break up large orders into several shipments going to different addresses and none of them at the grow location. I detailed my ordering experience here at: http://boards.cannabis.com/rhino-can...ng-online.html if you're curious about the process.

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Originally Posted by Lemuel714

The ones I'm using are the Steinernema Feltiae. I've used them along with the mosquito dunks which I crumbled and put in the soil. I also put two dunks in a five gallon bucket and have been using it to water with since.

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Question, where did you get them from, local or online?

@ThePinkJina, I got them on ebay. Dr Pye's Scanmask...There's videos on youtube on how to use them. I did not spray them on though. I just watered with them. @Keiser, I've never heard of either of those strains, let me know how they turn out. I got my seeds from BC. I started out with 4 different strains. They were all OK. I didn't pay much for them though and all in all I was real happy with the service I got from those guys. 150 plants is a lot for me, probably 2/3 were clones and 1/3 were seedlings. Like I said, I had just had a big come up in seeds. I was getting a lot of stunted growth and on top of that I had had my veg and flowering room together for a little while when summer ended. Its a big room and I had it sectioned off so I thought I would be ok but what happened was that my flowering plants got too much light (it wasn't much) and went back into vegetative growth. (another rookie mistake) So I'm kind of backed up. I try to keep it to where I'm harvesting something every week or two and I ended up going a good six weeks with nothing so being the neurotic I am I overcompensated and planted and cloned a lot more than I usually would.