soil fungus gnats

lolear(5b - Chicago)April 12, 2011

I have what I think are soil fungus gnats in my seedling area under the lights in my basement. (They look like fruit flies) When I noticed them a couple of days ago, I started trying to dry out the soil a bit. Then today I noticed a white fungus (?) covering the surface of the soil on just a couple of the seedlings. I scraped this off and added some dry medium to the top, hoping to absorb the moisture. I understand the larvae can feed on the roots of my seedlings and cause damage. I read somewhere that you can use bt on soil gnats. The bt I have is meant for cabbage moths. Is this the same/ will it work on them? Any other suggestions other than allow the soil to dry out?

Thanks,

Laura

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dan_staley(5b/SS 2b AHS 6-7)

Surely there are 500 threads on this board with people's tricks for keeping fungus gnats at bay. Choose the one that appeals to you.

Dan

    Bookmark   April 12, 2011 at 10:40AM
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lolear(5b - Chicago)

At the moment the only thing a search here turns up is a set of google ads for extermination services. Not quite the expert and friendly advice I was looking for.

    Bookmark   April 12, 2011 at 1:09PM
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loribee2(CA 9)

Funny you mention this, Laura, because as I was adding compost to one of my raised beds this weekend, one corner was COVERED in what you describe--little things that look like fruit flies. I just rubbed a cloth over and squished the bulk of them, shrugging them off, since I don't seem to have any pest problems with the spring veggies I've got growing.

But I'd be curious to see what people have to say about it. I've been following this forum for over year now, and have yet to see any conversations on them, so hopefully someone knowledgeable will provide a helpful reply! :-)

Here is a link that might be useful: my blog

    Bookmark   April 12, 2011 at 1:25PM
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jean001a(Portland OR 7b)

Use Bacillus thuringiensis israelensis (Bti), the same stuff in Mosquito Dunks and more, products used in stagnant ponds to kill mosquito larvae.

Add some to your irrigation water every time you water for the next 3 weeks. You have to continue that long in order to disrupt the life cycle.

    Bookmark   April 12, 2011 at 1:58PM
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rhizo_1 (North AL) zone 7

Dan (who appears to have risen from the wrong side of the bed today) is referring to the search option here in the GardenWeb. If you go to the top of any title page in any of the forums, you'll see small blue-line options for 'other forums', 'instructions', 'Post a Message', 'FAQ', and 'Search'. Click on Search, type in your topic, then chose "all forums".

Attached is the Search for Fungus Gnats. Also, these pesky insects are discussed often in the Houseplant Forum and in the Pest Forum (Plant Clinic). Like almost every day, it seems like, lol.

Let me know if you have any questions after reading a few of the threads.

Here is a link that might be useful: Let's read about Fungus Gnats

    Bookmark   April 12, 2011 at 1:59PM
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lolear(5b - Chicago)

I'm still getting just the ads by google when I do a garden web search. Even when I click on the helpful link above, it reverts to the same 3 ads and nothing else. I thought maybe it was my pop-up blocker, so I disabled it temporarily, but the same thing keeps happening.

Jean: I'm guessing the bt I have is not the same strain used for mosquitos (I use it to control cabbage moths). I have some ecosense garden sparay that contains pyrethrin and have used it as a soil drench (not on the leaves or stems since they are under lights). Hopefully this will disrupt the gnats and not harm the plants?

    Bookmark   April 12, 2011 at 2:12PM
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taz6122(N.W. AR.6b)

Do you NOT see the link rhizo provided?

1/4 of a mosquito dunk per gallon of water.

    Bookmark   April 12, 2011 at 2:27PM
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loribee2(CA 9)

Yes, now I'm thinking this is something I need to control before I plant my peas next weekend? They don't seem to be bothering anything at the moment, but they're right in a spot where I plan to plant snow peas.

Laura, does the link below work? It seemed to be one of the better conversations from the houseplant forum.

Here is a link that might be useful: discussion

    Bookmark   April 12, 2011 at 2:27PM
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loribee2(CA 9)

According to Laura, no, Taz. Rhizo's link was to a search result page. The link I provided above was to an actual discussion loop, hoping that might make a difference. Very strange problem, though I know this forum can be buggy at times.

    Bookmark   April 12, 2011 at 2:38PM
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susan_in_md(7)

I think I know what is happening when you try the search or the link provided. I get the same three ads you saw, with a lot of white space beneath it. The white space is so long, you think that's all there is. It took me a while to realize the search results were way, way, below that. You just have to keep scrolling down.
I don't know if everyone else's search results are displayed this way, but that's how mine always come up.

    Bookmark   April 12, 2011 at 2:39PM
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lolear(5b - Chicago)

For whatever reason I could not see the link rhizo provided, but I did get to see the one loribee posted. No clue as to why I can see one and not the other. After reading the houseplant link on fungus gnats I think i am on the right track. I also put a fan on them to help dry them out. As I don't have immediate access to mosquito dunks (not sure if I would find them locally at this time of year), I sprayed the soil with a product containing pyrethrin. Sounds like it should do the trick.
Thanks to everybody who tried to help!
Laura

    Bookmark   April 12, 2011 at 2:46PM
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rhizo_1 (North AL) zone 7

Wierd! I clicked on the link and it took me to the search results I had hoped would be of help. Some 900 threads' worth!

    Bookmark   April 12, 2011 at 3:10PM
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dennis_564

I've had fair success with mosquito dunks, however it would not work for me with straight (chlorinated) tap water. After I de-chlorinated the water they worked fine.

    Bookmark   April 12, 2011 at 6:13PM
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fool4flowers(8)

I keep a 5 gallon bucket of water and add a mosquito dunk to it and use this to water indoor seedlings and put in a fresh dunk about once a month. Its the only thing I found that really helps.

    Bookmark   April 14, 2011 at 10:20AM
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michelelc

I had a ton of fungus gnats on my peppers that I wintered indoors. I did 2 things and it drastically reduced (but not eliminated) the problem. I sprinkled cinnamon on the top of the soil and I began watering with a weak chamomile tea. Both are natural anti-fungals. Now I water all my seedlings with a weak chamomile tea. You can search on this topic, or google it and read about the benefits of watering with chamomile tea.
Also, if you want to get a more focused search scroll to the bottom of the forum you are on, just below the last post on the page, and use that search function. Make sure you click on search this forum rather than entire site. When I first started using this site, I used the search function on the top and found it impossible to weed through all the topics the search brought up. Good luck!

    Bookmark   April 15, 2011 at 9:46AM
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lolear(5b - Chicago)

Thanks everyone for the advice!
So far what I've done seems to be working. I see only a few adults at this point. I scraped any fungus from the soil, sprayed a product containing pyrethrin on the soil, and put a fan on the seedlings to help dry things out. I had one recurrence of the mold on one container, repeated the steps on that one. I also have mosquito dunks on order. But since I didn't have them at the time, I used what I had on hand available to me. I am keeping a close watch on the situation. None of the seedlings seems much worse for wear so I hope no permanent harm was done.
Thanks again!
Laura

    Bookmark   April 15, 2011 at 10:19AM
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taz6122(N.W. AR.6b)

I had a ton of fungus gnats on my peppers that I wintered indoors. I did 2 things and it drastically reduced (but not eliminated) the problem. I sprinkled cinnamon on the top of the soil and I began watering with a weak chamomile tea. Both are natural anti-fungals. Now I water all my seedlings with a weak chamomile tea.

Fungus gnats are an insect NOT fungus.

    Bookmark   April 15, 2011 at 10:45AM
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loribee2(CA 9)

I'm presuming from Laura's post that the goal is to get rid of the fungus that the gnats are being attracted to.

    Bookmark   April 15, 2011 at 2:54PM
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taz6122(N.W. AR.6b)

Lighten up! It was a joke.

BTW michelelc's who I quoted! Is that another Laura?

    Bookmark   April 15, 2011 at 4:35PM
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fool4flowers(8)

Every time I pot up amaryllis I get them gnats in the house. YOu can see them in the bag of potting soil when you open it. I wonder if its old potting soil in the fall that causes it.

    Bookmark   April 15, 2011 at 11:37PM
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taz6122(N.W. AR.6b)

If it is, your potting soil is too moist to begin with.

    Bookmark   April 16, 2011 at 1:00AM
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