whitefly - 2
HAVE a real problem with whitefly in my outside garden. It all started
when I transferred a tomato plant from my glasshouse into the garden.
The whitefly followed and multiplied in a big way. At the end of
March I pulled up the badly infested plants, put them in a plastic
bag and took them to the dump. However, the whitefly that got away
immediately took residence in a display of annuals (Salvia
'Victoria Blue'). I sprayed them with a mixture of Target and Conqueror
Oil and eventually reduced the numbers, but forgot to check under
the leaves for some weeks. When I did, I found they were everywhere,
even under the leaves of weeds. I want to replace these annuals
with winter ones. How do I get these insects under control?
despair, there is hope. Unless your garden is exceptionally warm
and sheltered, the adult whiteflies will die off in winter, leaving
their eggs under the leaves to survive until the weather warms up
again in spring. So if you pull up the salvia and dispose of them,
you should get rid of the problem, for your winter annuals at least.
You can put the salvia
in the compost heap. As the plants rot down, the eggs and any surviving
whitefly nymphs should die off.
To help avoid the problem
next season, get rid of any weeds around the place before the weather
warms up, as they could be harbouring eggs. Also, next season check
your plants regularly, both outdoors and in the greenhouse, especially
under the leaves, for early signs of infestation. The sooner you
take action the better, before the whitefly population gets well
Some whitefly may survive
as adults all winter in your greenhouse, so if you still have susceptible
plants in there you'll need to keep up the spraying programme. For
a bad infestation in warm conditions, such as in a greenhouse, you
need to spray every five days or so for at least three sprays in
order to really disrupt the whitefly life cycle of egg, nymph and
Gardener, Issue 174, 2005, Page 28
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.