Detergent vs Soap as an Insecticide
Posted: Jul-06-2004 at 6:23pm
When they say--spray your aphids with soapy water, are they talking detergent or real soap? Is there a diffrence that is significant to the aphid? Or is the idea just to break down the skin surface of the critter and cause it to dehydrate. I read Jerry Baker, and he talks about lemon soap for use in his mixtures. but I think the lemon soap he refers to is a detergent. I emailed his site, but never received an answer. Can someone clarify this for me, please.
Posted: Jul-06-2004 at 6:56pm
From Rodale's Chemical-Free Yard and Garden comes this information regarding insecticidal soaps:
"The great advantage of soaps is that they are not toxic to people, birds, and other animals. Soaps are the salts of fatty acids, which are common in all living things. . . Soap has varying insecticidal effects against certain groups of insects, depending on the kind and proportions of fatty acids and base used. Soaps kill insects on contact by paralyzing them, disrupting membranes, and affecting their growth and development. Beetles are less susceptible to soap, so lady beetles are relatively safe, but soap sprays do kill their larvae." This kills on contact, so be sure to spray top and bottom of leaves to get as many of the baddies as you can.
To make your own: "You can use household soaps, such as Ivory Snow, Ivory Liquid, or Shaklee's Basic H to make insecticidal soap solution."
So it seems soap is what you want, not detergent. They are both cleaning agents but the chemical make-up is slightly different between the 2 (and don't ask me how, I'd have to google that).
Also from the above source: Soaps can damage some plants, particularly those with "thin cuticles, such as beans, Chinese cabbage, cucumbers, ferns, gardenias, Japanese maples, nasturtiums, and young peas, are easily damaged by soap sprays. Tomatoes and potatoes are less susceptible to damage, and cabbages seem virtually impervious, although lowered yields have been reported after heavy use of soaps." This source recommends using no more than three successive soap sprays on any particular plant. They also suggest spraying on overcast days or in the evening to lessen leaf damage.
Okay, this is my opinion coming atchya. Be cautious with information from Jerry Baker. Much of it is likely harmless, some of his remedies are a waste of time (there are better, easier to use, tried and true remedies than his concoctions) but some are unsafe, and to my knowledge, cautions are not mentioned with the remedies (and my reason for cautioning you about his advice.)
Posted: Jul-07-2004 at 9:06am
I also heard from my "Mom in law" that Lemon Joy or other lemon dishwashing soaps work well. Old school perhaps, but tried and true all the same.
Posted: Jul-07-2004 at 10:47am
Thanks, Now I am really glad I waited to spray the cabbage! I was really frustrated when Baker was on OPB last year with his helpful advise, but the online site did not respond to what I thought was a reasonable question. --and I have wondered if his home-made remedies were not just as expensive as the commercial stuff. Sorry gotta run, it is overcast and I must spray!
Posted: Jul-07-2004 at 5:47pm
When the weather/planting cycle is "wrong" and I get aphids on my Brussels sprouts in late summer, I prefer to use something like Safer's pyrethrum spray. This organic spray is toxic to bee and other beneficial insects but I don't get many of those near my cole plants unless I am waiting for the seed instead of the green harvests.
I've tried using water sprays with my pressure sprayer to knock them to the ground but too many get back and every female aphid already has pregnant babies in her body. That takes too many sprays!!!
Posted: Jul-13-2004 at 2:59pm
I've heard that you're better off using a commercial soap preparation, such as Safer's insecticidal soap, because different dishwashing soaps have varying strengths (and ingredients), and you could risk doing harm to your plants.
Posted: Jul-14-2004 at 8:57am
I've had good luck using the hose spray for my rose but not nastursiums. They congregate on the underside of the leaf so it's harder to get them with the spray. I just yank out the nastursiums when they get too bad.