Disinfecting seeds

Rodger Whitlock totototo@mail.pacificcoast.net
Sun, 14 Dec 2003 07:21:39 PST
On 11 Dec 03 at 10:41, Jamie wrote:

> Another problem I have, and perhaps some of you have methods to
> combat it, it fungus flies (or similar).  They lay their eggs in the
> medium and the nematode-like larvae eat the seeds!  I've tried Neem
> and insecticides that are on the European market watered in, but
> without real effect.  Sterilizing the earth is not the answer as the
> flies could care less!  Anyone have a good method?

Two things come to my mind.

One: You need to clean up your growing area. It was one of the 
great advances in human understanding when it was realized that there 
is no such thing as spontaneous generation of organisms; those fungus 
gnats are coming from somewhere, most likely your other potted 
plants. Get rid of the infestations in those and your seed pots will 
not become infested in turn.

If it's impossible to clean them out entirely, try screening your 
seed pots with fly screen, cheesecloth, or something like that.

Two: Perhaps your seed mixes are too peat-rich. Traditional 
horticultural lore associates fungus gnats with peaty potting mixes. 
This may be complete b.s.

I have a number of ordinary large-flowered hippeastrums that have to 
overwinter in the house, and fungus gnats sometimes become a 
nuisance. I have found that an ordinary pyrethrin-based household 
insecticide spray does a good job of controlling them. If you spray 
about once a week, being sure to get at the soil surface, their 
numbers decline very rapidly.

Pasteurization of the growing medium before sowing is, of course, 
essential in order to destroy any fungus gnats in it.

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

on beautiful Vancouver Island

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