white fly?/house gnats???

Discussion in 'Gardening & Plant Propagation' started by thefarm, Feb 21, 2004.

  1. thefarm

    thefarm Well-Known Member

    Messages:
    624
    Joined:
    May 10, 2002
    Location:
    Maine
    :confused: ok I'm confused on what to do.. I have 2,100 plugs going and 14,000 coming on March 1st.. Well now I'm getting this thing that looks like a fruit fly but I think it's white fly or house gnats?? I'm spraying all the time to keep the plants moist. I bought some of those yellow sticky cardboard looking things and they work ok.. But I really need to use a spray because with the large amount I'll be getting don't need a major problem... Looking for some help thanks... Brenda Happy Planting...
     
  2. Whiteflies look like tiny white moths and live mostly on the underside of plants' leaves. The larvae feed on the plant sap and debilitate it and can also carry disease. The adults are attracted to yellow sticky cards; freshly caught adults are white and dead ones turn into little dark tan specks.

    Fungus gnats/shore flies look like tiny little house flies. They fly up from the surface of the soil and deposit fecal specks all over the tops of the plug trays. The larvae live in the soil and feed on algae growing there; there have been some who say that they will also damage tender roots. The adults are attracted not only to the yellow cards, but better to light blue ones.

    Whiteflies like warm, dry conditions. Insecticidal soap works well for us (use a specific insecticidal one, not a dishwashing detergent one which can burn seedlings). Since it is a contact killer, you will have to make sure the spray contacts all the underleaf area to get the larvae. There are other chemicals which work, and once you have identified which insect you have, anyone who sells the products will be able to help you.

    Since the algae is the root of the problem with fungus gnats, it's best to get rid of that (the adults only live about 3 days and do not harm the plants -- but they're a nuisance). Let the seedlings dry out a little between waterings if possible, but don't let them wilt. This is kind of hard to judge with the small root ball of a plug, but it's possible. We have used parasitic nematodes in the water to kill the larvae; we now use bromine in the water to prevent algae growth. The disinfectant Greenshield also works well, but isn't labelled for on-the-plant use (but we've done it anyway . . .). There are also chemicals that you can drench with to kill the larvae, and sprays to get the adults.

    Best of luck! Insects on plant babies are no fun.

    Marcia in MT (not logged in)
     

  3. thefarm

    thefarm Well-Known Member

    Messages:
    624
    Joined:
    May 10, 2002
    Location:
    Maine
    Thanks for the info.. I guess you would call it fungus gnats because when they land on the yellow sticky card they are brown and look like a fruit fly .They :) are in the soil because when I water they fly up... Would I get something from a greenhouse supplier? This is new to me.. thanks Brenda
     
  4. You could use Diazinon to kill the adults as a spray and the larvae as a soil drench. A greenhouse supplier would be able to sell you the concentrate -- a lot -- at a better per-use price than a local garden center. But depending on how much you'll ever use and how safely you can store chemicals, you may want to get a smaller amount from a garden center, department store, etc.

    Sounds like you are going to raise plants in a big way (good for you!) -- so you might want to cultivate a relationship with your greenhouse supplier representative. This person will not only know what their company carries, but how to use it and on what. They can be useful people -- as long as your sales resistance is pretty high, you won't be talked into anything you really don't need.

    Marcia in MT
     
  5. Dchall_San_Anto

    Dchall_San_Anto Active Member

    Messages:
    27
    Joined:
    Feb 17, 2004
    The organic solution to fungus gnats is Bacillus Thuringiensis israelensis. You can get that in a product called Mosquito Dunks at any garden store including Wal*Mart. If you soak a dunk in a gallon of water and spray with that water, you should take care of the gnats.
     
  6. thefarm

    thefarm Well-Known Member

    Messages:
    624
    Joined:
    May 10, 2002
    Location:
    Maine
    Thanks so much to no... Brenda :)