fungus gnats and Diatomaceous earth

Discussion in 'Cannabis Infirmary' started by d420, Sep 22, 2009.

  1. d420

    d420 Premium Farmer

    I was wondering how to make a foliar spray with this.(How much I should dilute it) I have a horrible fungus gnat infestation and have purchased some DE to help correct the problem. Thank you for all your suggestions.
  2. darookie2000

    darookie2000 New Farmer

    Do not let this stuff get airborn. The reason DE is effective for gnats is that it cuts their undersides as they try to fly into the soil. A foliar spray will do the same thing to your lungs. I have been fighting gnats for most of a grow, and the only tried and true remedy that I've avoided is DE, because it's just so nasty. If I had to, I would use it, but I consider it a last resort - I'd rather go for perlite, which I hate because of the floatation before risking my health with most DE preparations (I can really only find one type, the kind in the big yellow bag). Supposedly food-grade DE is safer, but I've never been able to locate it. Keep pets, kids, slow friends, etc. away from it, it's a severe irritant.

    The way to correct the problem, if you decide to use DE, is to put a layer of it on top of the soil. Make sure you get a mask and some eye protection, and probably gloves. It's nasty shit, and you don't want it getting on you. It will prevent adults from flying into the soil to lay eggs (well, it won't prevent them from flying there, but it will prevent them from living if they do), and prevent larvae from escaping once they become adults. However, the larvae can do quite a bit of damage to the roots before they emerge.

    Your best bet to get rid of all the adults quickly would probably be a pyrethrin bomb, but this is not great for the plants, and I'd use it as a last resort (this was my second to last resort before DE, lol, I used a pyrethrin spray once before I found out that it kills beneficials, and I have a bomb on standby, but I won't use it unless something far more threatening than gnats shows up - in other words, like an airbag, I hope I never have to use it). For the larvae and eggs, I have used a bunch of different things, and what has worked best for me is Azamax as a soil drench. I have only seen a hand full of gnats in the past couple weeks, since I went and got more azamax. I have also started using crushed mosquito dunks on the top layer of my soil, which seems to help a lot.

    Good luck! Oh, one more thing helps a lot, get faster draining soil or water less often!
  3. Jalisco Kid

    Jalisco Kid Well-Known Farmer

    Gnatrol or mosquito dunks for the larvae and what he said above. JK
  4. bigyieldsonly

    bigyieldsonly New Farmer

    try gnatrol water the top layer of soil a couple times a week ion a drysoil top with in 1 week most were dead
  5. d420

    d420 Premium Farmer

    Thank you for all the suggestions. I will try the perlite thing and if that does not work I will do the other things you guys suggested.
  6. heavydutykevork

    heavydutykevork Premium Farmer

    Look up GrowCo. on the net they got this stuff called Captain-Jacks Dead Bug spray it works great for gnats. I spray it on the plant, floor and around the grow area anywhere those fuckers hide i spray, and for the dirt they will give you Microbe-Lift 1 drop per 5 gallons. It work for me o yeah and sticky traps all around for awhile to get them too;)
  7. FastForward

    FastForward Moderator

    Its like most things - you gotta break the cycle.

    Drench your medium with an anti gnat product (I use GnatOff) to deal with the eggs
    Put up yellow stickies or a HotShot to deal with the adults
    Spray the leaves with an anti bug product every 3-4 days for a few weeks to deal with any hiding adults

    Do this for a couple of weeks and you should be golden

    FF
  8. markscastle

    markscastle Well-Known Farmer

    I know the nat larva will eat at roots and flying nats are a bother but plants don`t live long enough for nats to do that much harm. Best thing is to let the top 2-3 inches of soil dry up in between watering.You can put an inch if clean sand or perlite on top to keep em from putting any more eggs in the soil.I`ve used DE and it works well.You shouldn`t let it get air born or get in your eyes. Mouth won`t hurt you much.It is sometimes used to kill worms in dogs by adding it to there food but doesn`t seem to harm earthworms.It can build up and cake in the soil stopping water from soaking through so it shouldn`t be added in soil mix.Hope that helps!
  9. madcease

    madcease New Farmer

    How about treating these black eggs i got all over my rockwool since day one. There everywhere but havnt hatched it doesnt seem.

    Are these black small eggs fungus gnats?
    Have a pic 2 show soon
    SOGreenThumb likes this.
  10. d420

    d420 Premium Farmer

    for me I couldn't tell until the tops of my buckets looked like champagne glasses(Larvae flying around them, especially in mornings.) It's a pain in the ass. I just hope they do not get to my clones, which are rooted nd ready t transplant, but I can't because my soil is infested with gnats. Any suggestions?
  11. Jalisco Kid

    Jalisco Kid Well-Known Farmer

    The best cure is prevention. Use a noseum netting around your containers. JK
  12. Lost

    Lost New Farmer

    No pest strips FTW. Put it in for a week then take it out. Problem sloved :)
  13. supasticky

    supasticky Farmer

    When you transplant the clones put a layer of DE on the bottom and top(about 1/2 inch) of the container. Also you'll want to clean out your grow room and water your soil with one of the products mentioned before. The fungus gnats are not the main concern. Their eggs are. What happens is the fungus gnats lay eggs on your leaves and when they are ready to hatch they fall onto the soil and then attack the roots. With DE on the top they wont be able to get to the soil. The layer on the bottom is so that bugs can't go through the drain holes. All bugs. Also it provides your plant with silica and helps to strengthen your plants SAR(system aquired resistance); basically their immune system. Your fungus gnat problem should go away if you do this unless you're outdoor.

    -Supa
  14. Jalisco Kid

    Jalisco Kid Well-Known Farmer

    Supasticky how does DE kill insects? JK
  15. mc1969

    mc1969 New Farmer

    had them pretty bad one time done the sand on top of soil with a little cinnamon (seen an write up on it in an organic gardening mag ) mixed in and the pest strips and they were gone in a week.
  16. darookie2000

    darookie2000 New Farmer

    It's like poking their undersides with a bunch of knives. It cuts them up.
  17. darookie2000

    darookie2000 New Farmer

    Yeah, any light, quick-draining medium that is not composed of dead organic matter will work as a barrier. The idea is that sand, perlite or vermiculite will dry out quickly, and gnat larvae need to be in the top inch or two of the soil in order to be able to emerge from the soil when they grow into adults. If you put the layer on top, they can't get out, and the adults have a hard time getting in to lay the eggs.
  18. darookie2000

    darookie2000 New Farmer

    [​IMG] this is the only type of DE I have ever been able to find, and it's not food-grade.
  19. darookie2000

    darookie2000 New Farmer

    Yeah, I was just having trouble finding it locally. I would prefer not to use it if there was a safer alternative, so I would probably try perlite instead.
  20. darookie2000

    darookie2000 New Farmer