"Kay Easton" wrote in message
...
In article , Franz Heymann notfranz.
writes


Kay, could you do a bit of explaining please:

I presume that the development of a resistance to a pesticide is a
genetic
process. I envisage it as occcuring when one specimen undergoes a
genetic
modification in the desired direction, and subsequent sexually
transmitted
mixings spreading it through a population. If this is so, I don't think
one
will notice as quick an immunity as you imply.

Please tell me what I misunderstand.


I'm talking about a time scale of years rather than months.

Nuff said.

A greenhouse
is a largely closed environment, so it's more of a problem than the
garden generally. Certainly I no longer find pesticides effective
against mealy bug and red spider mite.

Generations in both mealy bug and rsm come thick and fast!

I understand better now, thanks. I had an impression (wrongly) that you
meant that the effect might be seen within a season.

Franz