Fungus gnats and control

Rodger Whitlock
Sun, 14 Dec 2003 09:27:50 PST
On 11 Dec 03 at 15:57, David Fenwick wrote:

> I once drenched pots with malathion for the fly, and all of them
> came to the surface coughing. I thought right I can blast them with
> something else now and used an aerosol, a household flea and fly
> spray containing pyrethrin. Boy it was good control and really
> successful for the fly. Sadly all the seedlings died as well, it
> would seem that the plants were phytotoxic to the butane propellant.

The death of your seedlings is more likely due to the malathion than 
the butane. Malathion is known to be phytotoxic to some plant groups 
and the label will say "do not apply to X, Y, and Z."

Butane itself is a very simple compound with very little
physiological effect to be expected other than possibly displacing
air temporarily. 

Other possible culprits include the pyrethrins themselves and the 
vehicle they are dissolved in.

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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