Neem for Gnats?

m_taggart(7b)October 11, 2007

I have my first plant pest, fungus gnats. They are ridiculously annoying. Does anyone know if neem will kill the gnats or their larvae? I bought some fly tape and cut it into pieces then put on top of the soil. It is catching some, but I want to eliminate them.

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kioni(3)

M Taggart: if you search 'fungas gnats' you should come up with some other discussions about them on this forum. The yellow sticky strips work well, but it seems to be they are hard to find? My local Wal*Mart carried them for a long time (Canada), but a while ago they were marked down near 1/2 price & this usually means that particular product is on the way out...I was just in the plant section there and the spot for them is empty. Maybe try your local greenhouse? The sticky strips do eliminate them, but it takes a couple of weeks to get them all, since the hatched ones need to grow to fly into the trap. Good Luck!

    Bookmark   October 11, 2007 at 6:59PM
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stacy_wisser

I was wondering if it would work. I had a discussion with my aunt about this today. It seems that they have just stocked her local Walmart with Venus Flytrap plants. We were wondering if they would be a good thing to keep around the other house plants to attract and keep the gnats and other flying pests down, along with general soil changes and upkeep.

I know it's a little off the wall, but we are thinking of trying it out.

Stacy.

    Bookmark   October 11, 2007 at 7:29PM
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tapla (mid-MI z5b-6a)

You would need very good light, warm temps, and extreme humidity to keep Venus flytraps happy - prolly not the best choice to keep gnats under control.

Neem works very well for keeping gnat numbers down. Find & use the cold-pressed product if you decide to use it - it is very superior to other products carrying the name 'neem' that are not cold-pressed.

Before you consider neem, though, examine closely your watering habits. You can usually keep gnats under control with good watering practice. In almost all cases, you can trace an upswing in gnat #s to overwatering and/or organic fertilizers.

Here is a link that might be useful: Read about neem by clicking me

    Bookmark   October 11, 2007 at 8:26PM
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watergal(z6/7 Westminster, MD)

I tried sundews to catch gnats, but they need too much humidity.

I've read that you can make your own sticky traps by smearing bright yellow cardboard with Vaseline. Sounds messy to me. I buy my traps online - just google "yellow sticky traps" and you'll find a bunch of vendors.

Keep the plants on the dry side, put out the yellow traps, make sure there is no standing water anywhere, and you should be OK in a few weeks. Try to buy good potting soil - cheap soil often is full of gnat eggs.

    Bookmark   October 12, 2007 at 7:01AM
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mr_subjunctive

I tried the Vaseline thing once (on bright yellow plastic, not cardboard, but still) and didn't find it to be useful. It got dusty, but only one or two fungus gnats landed on it in two or three months' time, and for all I know, those might already have been dead when they hit. Your results may vary, but I don't recommend it.

    Bookmark   October 12, 2007 at 10:07AM
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webkat5(Z6a MO)

I sincerely don't see how fungus gnats can be controlled with neem oil, since it is not the adults you need to be worried about.

Depending on the plant you have (most likely one that does not like the soil to dry out) you can easily rid yourself of these gnats.

Simply allow the soil to completely dry out for a day or two (keep an eye on the plant).

After the treatment, fill you sink with lukewarm (not hot or cold) water and then soak the plant (in the pot) for an hour or two until you are certain the entire root ball has absorbed moisture...allow it to drain thoroughly afterward. This will insure a reestablishment of proper/even soil moisture throughout the ball.

Fungus gnat larvae (which does the damage to plants by eating the new delicate roots in the soil) are very similar to termites in that they can not survive without moisture....if the soil dries, they die.

Plain and simple measure without the use of any pesticide or lengthy battle.

    Bookmark   October 12, 2007 at 1:00PM
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tommyr_gw

Venus fly traps are not an indoor plant and would not help much anyway. A D. Adelae or D. Capensis sundew or 2 would help a bit. Bright light, sit in a tray of rain or distilled water about an inch deep. Plus the sticky traps.

    Bookmark   October 12, 2007 at 2:00PM
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hornetwife(Flour Bluff Tx Z9)

I thought my watering habits were good, but I too have a serious problem with gnats. I am going to try to track down the culprit, but with so many plants it is hard. Can you buy Neem at a place like Home Depot? Does it help with spider mites? My china berry has spider mites right now, I am trying to save it.
Lori

    Bookmark   October 12, 2007 at 2:06PM
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tapla (mid-MI z5b-6a)

Webkat - You don't see how neem can control fungus gnats because you don't understand the mechanism by which it works. There is little in the way of immediate knockdown when you use neem, but it contains 1)powerful anti-feedants 2)anti-metabolites 3)chemo sterilizers.

This means that:
1) Adults and larvae alike will find plants treated with neem very bad tasting. Actually, it contains bio-compounds that disrupt the digestive cycle, but it's easier to remember that it makes plants taste bad. m;o)
2) Anti-metabolites do just as the term suggests. They disrupt metabolic processes. If you wanted an easy way to remember this effect, think: "It puts insects into a coma." They don't do much feeding or breeding in this state, so you can easily see the value here, I believe.
3) As a chemo-sterilizer, it makes plants unable to reproduce. Think of it as an oral contraceptive in this case, or one that's absorbed through the skin.

Which brings up another interesting tidbit. It makes the larvae unable to form chitin and stops pupation.

Understand better now? That doesn't mean you're wrong (at all) about the recommendation to examine watering habits. See my post, too: "Before you consider neem, though, examine closely your watering habits. You can usually keep gnats under control with good watering practice. In almost all cases, you can trace an upswing in gnat #s to overwatering and/or organic fertilizers." just a couple above yours.

Some are going to be very close to destined to have gnats as a result of inappropriate soils that will simply not allow them to water in a plant-healthy way. For those, cold-pressed neem oil is a valuable and effective tool for control of gnats & many other pests.

I'll leave a link to cold pressed neem oil (the Dyna-Gro stuff at the top of the page) from Home Harvest, but I suggest you shop around, because it's way over priced from them. I left the link because it seemed as wordy as me & may cover something I missed. I wish I'd have found it sooner - prolly woulda saved me lots of typing. ;o)

Al

Here is a link that might be useful: Click me & we'll be off to investigate cold-pressed neem oil

    Bookmark   October 12, 2007 at 3:01PM
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webkat5(Z6a MO)

Thanks for the link, Al, but I could not find a reference to the fungus gnat anywhere in that advertisement.

I am VERY familiar with the uses of neem oil (requires contact for success), and it does wonders for pests which live on and attack the leaves/stems (above ground portions) of the plant.

Fungus gnat larvae (subsurface only) are the ones doing the damage to the houseplants (and then only very minor unless it is a seedling).

You know, fungus gnats actually can represent a healthy environment within the soil...on the flip side, they do occasionally spread diseases to the plants, though (just like dust mites are known to spread the common cold to people).

There really isn't a need to spend money on anything when watering and poor circulation is nearly always the issue in the case of the fungus gnat. A dry pot of soil=dead Bradysia eggs.

If seeking a treatment is desired, one would fair better to soak the plant in Gnatrol weekly until the life cycle has been interrupted.

Please don't attempt to belittle where it is not due.

Thanks.

    Bookmark   October 12, 2007 at 7:36PM
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tapla (mid-MI z5b-6a)

There was no attempt to belittle anyone. I'm not a shrinking violet, and don't play that way anyway, but if I intended to belittle someone, it wouldn't be subtle. Sorry you took offense at my every day, matter of fact tone.

Actually, neem oil doesn't always require contact, as it works systemically, too - and, at extremely low concentrations.

Though unimportant, I'm also not altogether sure you really DO understand how it works. If you did, you'd recognize the value in killing adults and halting larvae from completing the growth cycle.

The original question was limited to the use of neem oil, not Gnatrol or any other control agent (which I might also easily have suggested), and I stuck to the subject with a considered response. When you countered my response with the admission that "I sincerely don't see how fungus gnats can be controlled with neem oil, since it is not the adults you need to be worried about... , I thought I could enlighten you.

I'm not just guessing at the effectiveness of neem for controlling gnats - I've witnessed it's effectiveness. Additionally, one of the main reasons I didn't go off on a tangent and suggest other control agents, is that, as you noted, neem IS so effective across a wide spectrum of pests and there would most probably be benefits secondary or tertiary to the main, gnat targets.

In closing, I think this bears repeating: Some are going to be very close to destined to have gnats as a result of inappropriate soils that will simply not allow them to water in a plant-healthy way. For those, cold-pressed neem oil is a valuable and effective tool for control of gnats & many other pests.

Al

    Bookmark   October 12, 2007 at 8:34PM
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m_taggart(7b)

Lots of good advice here. The plant is a pothos vine, actually 5 cuttings i rooted, that have been transplanted into the pot about two weeks ago. The problem is that the plants don't have very good root systems yet, so I need to keep the soil kinda moist. I'm afraid that if I let it dry out completely the plants will be super stressed and die on me. I'm using pretty decent soil, organic miracle grow potting mix. I've also recently covered the soil surface with perlite to hinder the gnats ability to get to the soil. All in all, I think I'll try misting and watering with the neem. Hopefully this will knock them out. Thanks for the help.

    Bookmark   October 12, 2007 at 9:28PM
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earthlydelights(6 pushing 7)

i had this same problem last year with my house plants.
i ordered a solution from gardens alive, as well as the sticky yellow papers. it took three applications to rid my plants of these annoying pests, but i was able to get it under control.

    Bookmark   October 16, 2007 at 11:21AM
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Drakens(5a)

I've used the bowl of vinegar and water to try to stop gnats, but I've never really kept track close enough to see how well it works. I do have some neem oil, I think I'll try that the next time I water and see what happens.

    Bookmark   October 18, 2007 at 9:51AM
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dirtdigr(5)

Hi,

I have used neem for fungus gnats inside on mature plants- it takes a while, but works. I've also heard that peppermint tea kills them quickly. My question is can I use the neem to spray seedlings? Can I soak the soil too? Is it better to bottom water seedlings with the solution? How about peppermint tea for seedlings- that would certainly smell better in the greenhouse!

    Bookmark   February 6, 2009 at 11:46PM
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watergal(z6/7 Westminster, MD)

al, do you use neem as a foliar spray or a soil drench?

    Bookmark   February 7, 2009 at 9:20AM
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tapla (mid-MI z5b-6a)

I used to use it as both - because it acts as a systemic and is effective at extremely low concentrations in the plant. My thinking was that the plant would take up additional azadirachtin if I drenched in addition to a topical spraying. I kind of got away from using it as a drench, simply because it proved so effective as a topical and I could see no real benefit from the additional investment in time/resources for double applications.

I do remember reading something scientific that spoke to its effectiveness as a drench when I wrote the article I'll link to . I should prolly put that on my 'to do' list so I can answer more definitively when next the question comes up, hmm? ;o)

Al

Here is a link that might be useful: If you want more info on neem oil - click me!

    Bookmark   February 7, 2009 at 11:37PM
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victoriiinox_yahoo_ca

I had fungus gnats recently on my Grewia and I did a two prong approach. I used a Neem Oil drench (1 tsp Neem + 1/4 tsp dish soap in 1 quart of water) and followed this by putting my bonsai in front of a fan for 2 days to dry up the top layer of soil where the fungus gnat larvae live and feed on the bonsai plant roots. The leaves have stopped dropping and new foliage has appeared (mind you grewia seems to be a very tough tree). No gnats since my treatment.

I highly recommend NEEM OIL!

    Bookmark   July 3, 2009 at 3:47PM
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tapla (mid-MI z5b-6a)

You need to repot asap. You might want to consider pushing a wick up through the drain hole(s) until you can get at it.

Did you use cold-pressed neem oil (such as the product packaged by Dyna-Gro) or one of the other products that have other insecticides added?

Al

    Bookmark   July 3, 2009 at 4:40PM
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maveriiick

I used Dyna-Gro. No more gnats...nada.

    Bookmark   July 4, 2009 at 10:54AM
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