"Sally" wrote in message
...
Despite my using companion planting, my greenhouse tomatoes are
becoming
infested with whitefly. Any recommendations of biological control
would be
gratefully received.
Thanks so much



I have used a wasp called Encarsia formosana, which is a parasite for
white flies and will kill all forms of the pest. These insects won't
remove all the white flies, but then you don't need to remove them
all, just reduce the population. I'm not sure of the name of the
company from which I bought them, something like Biological Controls,
but you can do a google search and easily find sources.

These come on a little card. You attach these to the plants, after
uncovering and the wasps then fly around and attack the white flies.
This is beautiful - they do all the work and there are no side effect.
These wasps don't attack anything but white flies.

The downside is they are rather expensive. However, I've not found any
chemical which controls sufficiently. I have had decent luck with Neem
oil, you might try that as a cheaper alternative. If you use Neem oil,
be sure to spray the undersides of the leaves.

Guy Bradley
Chesterfield MO
zone 6