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Re: Giant Whitefly

Jane,

UC ag extension  released whitefly predators both this year and last year.
It is a tiny wasp whose name I don't recall off-hand, but it seems to me
that it is not one that we can buy commercially.  They warn (plead, beg) us
not to spray pesticides on the whiteflies as the pesticide will also wipe
out the predator.

The best treatment I know of is simply blasting the heck out of them with a
really strong hose-end nozzle.  You  have to do it every week or so, but it
washes off the current crop of eggs (that white spiral pattern on the
bottom of the leaves), washes off the "cotton candy" filaments, and
scatters the flies.  Someone with a questionable reputation told me that
the weight of the water on the flies' wings forces them to the ground and
they die, but I haven't noticed that to be the case.

In my part of So Cal (San Diego), the weather didn't warm up until fairly
late in the Summer so our whitefly problem was far far less that last year.
Last year, we lost several large mature hibiscus plants and  other plants
to the buggers.  This year, the infestation has been so light that I've had
no problem managing it with water spray.

Since you are at the arboretum, perhaps you could get ahold of the
predators to use at your site.  I suggest you call your local UC extension
agent and ask.

Good luck and if you hear of any alternative treatment, please let us know!

Nan

Nan Sterman, Master Composter in residency
San Diego County, California
Sunset zone 24, USDA zone 10b or 11
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