[CH] Be careful using household soap sprays
Bob Batson (bob@sky.net)
Wed, 2 Jun 1999 14:25:05 -0500 (CDT)
As whiteflies act as a vector for some viruses, I thought the following
article would be applicable.
-------------------------------------------------------------------
Beware of Phytotoxicity Due to Household Soap Sprays
There is increasing interest in insecticidal sprays concocted from
household soap products--in part, because such sprays are inexpensive
compared to commercially available insecticidal soaps. Setting aside
the issue of legality (homemade sprays are certainly not registered with
the U.S. Environmental Protection Agency!), there are some highly
practical reasons to be wary of spraying with solutions containing
dishwashing detergents. Greenhouse and field trials conducted at
Colorado State University have shown that tomatoes (and thus, by
implication, probably many other crop plants, as well) are susceptible
to damage due to detergent sprays. In the greenhouse trials, the sprays
that gave the best control of whiteflies also tended to cause the most
damage to tomato leaves. It is interesting that the commercial
insecticidal soap "M-Pede" was not very phytotoxic, but it also didn't
control whiteflies very well. Among several low-toxicity sprays
compared in the greenhouse trials, only "Sunspray" horticultural oil
(2%) provided good control of whiteflies with moderate phytotoxicity. In
the field, yields were much lower with weekly sprays containing 2% "New
Ivory Clear" detergent than with no sprays at all! Yields were improved
only slightly (but NOT with statistical significance) by spraying
weekly with 2% "Sunspray" oil, neem oil ("Margosan-O"), "M-Pede" soap,
or "Guardian" garlic water.
Reference: D. Casey Sclar, Daniel Gerace, Andrea Tupy, Karen Wilson,
S. Aaron Spriggs, R. Jason Bishop, and Whitney S. Cranshaw (Dept. of
Bioagricultural Sciences and Pest Management, Colorado State University,
Ft. Collins, CO 80523), "Effects of Application of Various Reduced-risk
Pesticides to Tomato, with Notes on Control of Greenhouse Whitefly,"
_HortTechnology 9(2)_, April-June 1999, 185-189. (American Society for
Horticultural Science, 600 Cameron St., Alexandria, VA 22314-2562.)
-----------------------------------------------------------------------
Reprinted with permission from the May 1999 _HortIdeas_. Copyright 1999
by Greg and Pat Williams. _HortIdeas_ (ISSN 0742-8219) is published
monthly by Gregory and Patricia Y. Williams, 750 Black Lick Road,
Switch, KY 40328 U.S.A. Annual subscription rates: U.S., $20 periodicals
or $22 first class; Canada and Mexico, $26; Overseas, $30 surface mail
or $35 air mail. Single issues: North America, $2.00 each; Overseas,
$3.00 each, surface mail, or $3.50 each, air mail. The email address for
_HortIdeas_ is: gwill@mis.net. _HortIdeas_ is now on the world wide web
at http://www.users.mis.net/~gwill/
====================================================================
Bob Batson L 39 12 14 N 94 33 16 W
bob@sky.net Kansas City
TCS - Mystic Fire Priest USDA zone 5b
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Under the most controlled conditions, the experimental apparatus will
do exactly as it pleases.