Fungus fly!!!! Neem ' em or?

mossback1971June 13, 2011

I have Dyna-Gro Neem oil. What is the best way to use it? Can I use it as a soil drench and foliar spray? Thank you

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from what i have been told the soil drench works best as it kills the larvea. I too had a bad case, i bought yellow sticky taps and i kill whatever ones i can. my soil is too wet right now to drench so i am hoping that the sticky traps gets all of them or i will drench with liquid BT once the soil is dry.

    Bookmark   June 13, 2011 at 4:15PM
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What is liquid BT?

    Bookmark   June 13, 2011 at 5:16PM
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I've tried it all, back when I HAD a fungus gnat problem. They just managed to come back over time, and it became an endless battle. How did I get rid of them you say? Well, I switched my potting mix from the peat based bagged soil, to gritty mix and 5-1-1 mix. Without the decomposing organic material that was in the bagged soil, the gnats don't have anything to feed on. Since I switched, I am gnat free!


    Bookmark   June 13, 2011 at 5:28PM
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Ohiofem(6a Ohio)

Well, I had fungus gnats many years ago when I was growing my vegetable starts indoors and got rid of them by using BT -- a form of the bacteria Bacillus thuringiensis specific to gnats (not the same as the one specific to cabbage worms or mosquitoes). It is sold as Knock-out-Gnats and under several other brand names. You need to use it as a soil drench because the larva are the real problem. I expect it would be more effective than neem oil, although I don't know since I haven't used neem to address gnats.

The best way to deal with fungus gnats is to keep your potting soil as dry as you can without harming your plants. The 5-1-1 should allow you to do a better job of that than the peat based seed mix I was having trouble with so many years ago, but I have to admit it is doing a worse job for me. In fact, I have several containers outside with 5-1-1 that are teaming with fungus gnats about three to six weeks after I first planted them. In almost 20 years of container gardening, I have never had any problem with fungus gnats outside. I don't remember seeing more than one or two over the years.

I was really surprised to see this happen because I like the 5-1-1 so much, and my potting soil is definitely not soggy. The recipe I used in these pots is exactly as Al recommends: 5 parts pine bark fines, 1 part sphagnum peat and one part perlite. The only thing I can think is that some of the pine bark mulch I bought from a hardware store had fungus gnats in it. It was on sale and pretty soggy when I got it. We had huge amounts of rain in the first month after I began setting out my plants in 5-1-1, and I think that's what gave the gnats the ideal conditions to multiply.

I am not concerned about my outdoor containers because fungus gnats can't do much damage to an older plant that is growing well, and the plants I put in these pots are mostly veggies that are growing extremely well. And besides, I expect dry weather, birds and beneficial insects to take care of the problem pretty soon.

Here is a link that might be useful: More than you ever wanted to know about gnats

    Bookmark   June 13, 2011 at 6:02PM
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I concur... fungus gnats thrive in a moist or wet environment. Keeping the medium and environment drier will discourage fungus gnats. Using a medium that dries out in a timely fashion is probably the best approach, especially since it's better to not have to resort to chemicals.

I agree... the 511 mix will help solve any drainage issues that allow a medium to remain too wet for too long, or hold perched water, as it's called. A medium of larger particulate is also better for aeration and compaction issues. I definitely recommend taking a deeper look into mediums like the 511 or Gritty Mix. Your plants will thank you. :-)

    Bookmark   June 13, 2011 at 7:11PM
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Mosquito Dunks hold the right strain of BT (BTi). Break off 1/4 and dissolve in a gallon of water. Water or drench the plant. You'll need to reapply after 7-10 days in order to attach the newly hatched little stinkers.

    Bookmark   June 14, 2011 at 9:01AM
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Aren't fungus flies due to too much peat? Eliminate the peat and the FF are gone (no reason for them to stick around).

    Bookmark   June 14, 2011 at 11:39AM
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I found my problem! I have a thick bed of bark chips that my smart pots sit on. Fungus gnats are below the surface of the bark and infested my pots. I'm using Al's 5.1.1 mix and I still have them. I put some Mosquitoe Bits on the bark bed and used some dunks in a watering can. I also used Dyna-Gro neem and Pro-Tek as a foliar spray for the adults. I'll see if the works!!!

    Bookmark   June 15, 2011 at 2:03PM
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noss(Zone 9a Lafayette, LA)

Will Neem oil sprayed on fig trees in high 90s-low 100s temps harm the trees? One of my little trees has scale--came with it and I didn't know what it was and now it's all over the trunk and running up the leaf stems onto the leaves. It's a container fig tree, just a little tad right now, but it wants to grow and can't.

I was told to make a mixture of rubbing alcohol, soap and neem oil and spray it onto the tree.



    Bookmark   June 17, 2011 at 12:27AM
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Ohiofem(6a Ohio)

I understand that scale is one of the few insects that is not very susceptible to neem. That's probably because they need to feed on leaves that have been sprayed directly to be killed, and with their little shells, they are feeding on a part of the leaf or stem that is not exposed to the spray. Although the alcohol and insecticidal soap spray might help some, the best way to get rid of scale is to scrape them off, with your fingernails if you can stand touching them. That little "shell" they have is almost impermeable to poisons.

    Bookmark   June 17, 2011 at 4:19PM
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noss(Zone 9a Lafayette, LA)

The soap was dish soap, not insecticidal soap and it seems the alcohol can kill the creatures. I think the soap acts as a surfactant and breaks the adhesion of the little suckers. :)

It was the neem oil I was concerned about and using it in the high heat we have in Louisiana and if it would harm the fig tree. I've heard that it's not good to use oil on trees in cold weather because it can harm the trees, but that doesn't seem right because if you can't use it in cold weather and can't use it in hot weather, then when the heck CAN you use it???

I don't mind smooshing the scale creatures. They remind me of barnacles. I was also told that they don't come off easily unless they are dead. Is that true?

I was told that the oil will smother the scale, but the person was talking about dormant oils and I checked and was told by Ortho that something like Volk (sp?) can't be used on fig trees.

I've also been told to use a q-tip soaked in alcohol and just dab the scale off the tree.

The more I'm told, the more confused I become.


    Bookmark   June 18, 2011 at 4:19AM
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