View Single Post
  #7   Report Post  
Old 16-11-2006, 11:34 PM posted to rec.gardens
Just Asking Just Asking is offline
external usenet poster
 
First recorded activity by GardenBanter: Nov 2006
Posts: 2
Default Fungus Gnats and Pyrethrum

"Father Haskell" wrote in message
oups.com...

Just Asking wrote:
I have a few questions:

1) Can you kill fungus gnat larvae by drenching the soil with a pyrethrum based solution?


Yes. Also, permethrin family insecticides, synthetic pyrethrins fine
tuned
for better kill and longer persistance.

2) Can you kill fungus gnat larvae with hydrogen peroxide (h2o2)?
Will this kill the plants? If not, what is the best strength?


I've used 3 percent drugstore peroxide cut to 1/2 percent without
causing noticeable harm. Kills the gnat larvae indirectly, by killing the
fungus that turns healthy root hairs into gnat food.

Tried cultural fixes? Try root pruning and repotting in clean soil.
Then cut back on water. Drowned (and dead) roots is what draws gnats.
Near-terminal cases may require taking and rooting cuttings and hoping
the fungus infestation hasn't become systemic.

Have you done a potato test to get a positive on fungus gnat larvae?
I wonder if it would be possible to use spud slices as bait to draw
the little buggers to your dose of pyrethrin or BtI, allowing more
kills with less poison?


Val and Father Haskell,

Thanks a lot, that is great advice. I expecially will try
cinamon (in combination with neem oil for the adult insects).
And I finally have a good dose for the H2O2 solution.
I'll also try a soil drench with pyrethrum, when my
plants are more established.

Thanks.