Fungus Gnats that will NOT die! Let me know how you deal with em please.

Discussion in 'Plant Problems' started by BamaGrower, Jun 2, 2012.

  1. BamaGrower

    BamaGrower Registered+

    Here is the situation:

    Six plants in six five gallon containers. I (stupidly) used miracle grow potting soil and consequently about a month into my veg grow these fungus gnats started showing up. I ordered Azatrol upon some advice from my local grow shop and it has helped cut down the population but, it just cant seem to get em all gone. I have excellent airflow and only water about every four days at most(sometimes every 5 if soil is damp enough). Plants look great to me and have grown about 1/4 to 1/2 inch every day on average for first 2 months. Temp is 76 to 80.5 "daytime" and never drops below 71 at "night". What can I do to finally knock these things out. Ever tried about an inch of sand(salt free) on top of the soil?

    Please pass on your experience and knowledge to me in regard to these flying nightmares.
    Just the thought of some larva below the soil snacking on my girls infuriates me.

    BTW--- got 4 papaya strain, one critical sensi star, and one caramello. all female happy to say. just started the flowering stage about one week ago.

    I gotta give the members of this forum about 90% of the credit on my luck so far. You guys(and gals) are a hell of a resource for a newbie that would be struggling otherwise.
    Thanks in advance for your attention to this matter.
  2. silent leprechaun

    silent leprechaun Registered+

    Hey duse.

    Sorry to hear about your gnat issues... the biggest reason for getting gnats is over watering.

    So here are 3 ways to get rid of them which I use.

    First I use pure camomile tea, put 1 - 2 tea bags in a 3 litre pot. Boil the kettle and pour in the boiling water in the teabags. Boil about 2 litres of water.

    Let this pot sit overnight to cool off and let the teabags filter. Maybe start on a light mixture with just one teabags to begin as too much chamomile can be harmful to roots.

    This is the first attack on the bugs. It attacks the fungus they feed on making it inaccessible to the gnats.

    Second, get your hands on some neem oil. Fill your water sprayer with hot water and add 5ml of soap/detergent (biological).
    Shake the bottle so the soap is dissolved fully in the water. Then take 5ml of pure neem oil, heat it lightly to make it a liquid, and add it to the sprayer water.
    Shake the bottle very well, the soap should allow the neem oil to mix well with the water.

    Then spray all over the plants; the leaves, the top soil and the base of the pots. Also make a bucket of the stuff for your next watering/feeding.
    The neem oil doesn't kill the bugs straight away. It confuses the insects so the stop procreating, eating, flying and also stop larvae from hatching.
    Gnats can live to up to 3 weeks so give the plants one watering with the neem mixture but continue to use the neem spray for up to 3 - 4 weeks.

    Thirdly, cover the top layer of the soil in a half inch of sand, be sure the sand is sterile. The gnats won't lay eggs on sand.

    That should be it. 100% organic method to kill gnats.
    So with these 3 methods you cut off their food supply, stop them laying eggs and also confuse the gnats literally to death.

    Take care buddy

    Last edited: Jun 2, 2012
    • Like Like x 2
  3. killerweed420

    killerweed420 Registered+

    Here's the simple organic fix for a lot of these bugs. Just put out a small bowl of mollasses. Almost all bugs love the sugar and once they get stuck in the mollasses they can't get out.
    • Like Like x 1
  4. cannabis-seeds

    cannabis-seeds Premium Sponsor

    This won't get rid of them, but it might help cut them down.

    I had a problem with fruit flies last year after an overabundence of tomatoes that we just couldn't keep up with.
    I tried all the homemade traps. They worked, but not nearly as good as those ugly glue tape strip things that cost about $1 for 4.

    I don't know what they put in that glue, but they loved it. Of course, it only helps keep the numbers down. You won't get rid of them completely until you take care of the source of the problem.
    • Like Like x 1
  5. mattj12pint2

    mattj12pint2 Registered+

    pick up some hot shot and hang them in ur room, they work great on flying insects, 2nd get some neem oil. its all organic. it works great. makes the bugs forget to eat and mate and stuff. let ur soil dry out more and make sure to keep ur humidity down also. p.s. the neem oil u can use up to the day before really works
  6. mattj12pint2

    mattj12pint2 Registered+

    u can get them both at homedepot very cheap
  7. BamaGrower

    BamaGrower Registered+

    Thanks for all the info gentlemen. I will get to work on these methods ASAP.

    BTW- how much damage can these gnats do to my girls? This is my first grow indoors so I don't have much to compare my current plants to. They appear super healthy and have great color/growth rate. The ph of my water that drains from the bottow is about a 5.5 to 6 and humidity levels peak at 55% but generally stay at 45%. That in itself is a miracle for living in coastal Alabama. Humidity outside in June is generally 70-90%. The only thing that happens is one of my plants has few fan leaves that are curling under just a bit. I doubt this is due to gnats. From all the research i have done it seems to be a nute issue and has improved as I started to adjust the ph of the water that drains from my soil.
  8. silent leprechaun

    silent leprechaun Registered+

    You will be very surprised by how quickly these gnats will destroy your plants. In about 3 - 5 weeks left alone they will kill a plant.

    Unchecked I have had a house plant almost completely die from them. 80% of the plant suddenly died so I washed the soil off the roots and replaced it.

    I even attacked the little bastards with chamomile and neem oil... even after I washed to roots !

    You don't need to wash the plants if you catch them early with the neem oil. But this plant was very near total destruction though. It still lives today !!!
  9. BamaGrower

    BamaGrower Registered+


    After my post about this issue with Fungus Gnats one of my Papaya plants started to show signs of wilt on older growth(fan leaves mostly). 48 hrs later it was a little worse. I decided to attack it with little regard for burning the plant because I assumed that it would die from the gnats if I didnt get drastic. So, I just mixed a huge amount of ground cinnamon into the top 2 inches of soil and then placed a generous dusting on the top of the soil. I did this on all my plants but went extra heavy on the one that showed signs of stress. I put out a shallow bowl made up of water, dish soap and enough coke(soda) to color the water brown. 12 hrs later and I counted over 30 adult gnats floating in the bowl. 24hrs later I used a 15% mix of water and Azatrol in a spray bottle and I saturated the top 2-3 inches of soil. I decided to add another fan so all my plants are getting a large amount of airflow and all the leaves are in motion at all times. As of today I estimate the adult population is less than 10% of its former size. I know the true test is with the larva. The Azatrol is supposed to keep the larva from reaching the adult phase which should break the reproduction cycle. None of my other plants seem to be showing signs of any damage(yet?????) I really hope that my first harvest is not worthless or tiny due to these god awful things.

    Thanks to all of you for your help.
  10. BamaGrower

    BamaGrower Registered+


    As of today my gnat problems are 99% gone. The ground cinnamon gets the credit along with a healthy dose of Azatrol.
    now to do something about that wilt!

Share This Page