Fungus gnats control

Kenneth Hixson
Tue, 09 Dec 2003 11:36:51 PST
Dear members:
>Fungus gnats are a problem sometimes.  One thing I do is to avoid using peat 
>moss unless the seeds really want it (e.g., azalea seeds).  Peat moss and 
>too-damp soil can lead to amazing numbers of fungus gnats.  

	It is generally agreed that fungus gnats only lay eggs in/on exposed
organic matter.  Some people feel, probably correctly, that the organic matter
must be moist.  Keeping the pot surface fairly dry helps. A fan to circulate 
the air, and disturb the adult gnats, also dries the soil surface.
I seldom have problems with rhododendron seed pots, even though I use half
and half perlite.  One simple solution is to cover the organic matter with 
something-I've used small gravel (aquarium "sand", "chicken grit" or blasting 
sand) on the top of the container.  Blasting sand is the stuff they use at
body shops; (80 pounds of it a few years ago cost about $4) which also helps 
prevent soil spatter in pots going outside to be rained on. Perlite,
Pumice or similiar materials can also be used.  It only needs to be deep
to cover the organic matter, about 1/4 inch/1 cm deep.
	Using a soap solution spray will kill the "maggots", but will not kill
adults, unless you hit them, and does not kill eggs, so the treatment needs
to be repeated every few days for about two weeks.  A vacuum cleaner will suck
up the adults if you can get the hose tip in amoung your plants--but it will
suck up leaves as well.  You can "herd" the flies to the hose by just slowly 
moving your hand over your pots toward the hose.
	Lysol--coat the interior of a plastic bag with 1 capful before inserting 
the seed-container.  Diluting Lysol with water and spraying the container and 
seedlings.  Or add a capful with water to the tray under the container and 
seedlings to bring the Lysol from the bottom.
	Yellow sticky traps will work to catch the adults, but a glass of wine 
or cider-vinegar placed next to the pots will get them even faster - they are 
immediately attracted to it and will drown themselves (happily in the wine?)
The larvae are still in the soil and must be dealt with before they "hatch " 
and start the entire cycle over again.  Bacillus thuringiensis, subspecies 
Israelensis as a soil drench will kill the larvae.  Several applications
may be 

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