sam wrote:
[...] For many years I have sown a small tray of French Marigolds in
my
greenhouse in order to discourage whitefly, and it has never
failed.
[...]
understand that tagetes are also good but I have never tried them
myself).[...]

You have, though: French marigolds _are_ tagetes! OK, so are African
marigolds, but I think a lot of the ones around are crosses between
the two anyhow.

--
Mike.