Re: [gardeners] Re:soap

Kay Lancaster (
Wed, 10 Mar 1999 17:19:46 -0800 (PST)

On Wed, 10 Mar 1999, T.L.Miller wrote:

> BTW, we've had a discussion on which is more effective on inscets, soap 
> or detergent. Do they kill insects in the same ways? Any opinions?
> I've used both dishwashing detergent and soaps like Murphy's Oil Soap and 
> seen no negative effects on my plants.

Different brands of soaps and detergents burn different plant species.
Best way to avoid problems is to avoid spraying in direct sunlight or
when temperatures are over about 85oF, and to wash off the plant with
plain water an hour or so later.    University of California's
horticulture department compared leaf damage with various brands of
insecticidal soap and plain old Ivory liquid dish detergent, and
found damage from each to some plants, but each soap or detergent
damaged different species... so none were clearly superior to others.

I've seen different explanations to why insecticidal soaps and detergents
work, but as near as I can tell, they both work by partial dessication
of the insect.

Personally, since I hate cleaning sprayers, I try a good blast of water
from the hose first... repeat for a couple of days, and usually that
does it for me.

Kay Lancaster
   just west of Portland, OR  USDA zone 8 (polarfleece)

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