Thursday, April 09, 2015

Insecticidal Soap, not just any soap

I always thought soapy water was the recipe for controlling bugs on tomatoes and peppers but it turns out soap is not just soap. I'm researching because my usual dish soap and water mixture this year is not working and I may have lost my tomato plants early. 

An insecticidal soap is a potassium fatty acid soap (aka -- natural) as opposed to a synthetic detergent. It's much more like what would have been made in the home 150 years ago before chemical engineering designed something that will clean better. These old timey soaps work well for simple dirt but not well for stains. Here are a few that are considered insecticidal ---- Zote, Fels Naptha, Roma, Dawn(?)

Insecticidal soap works best on soft-bodied insects and arthropods such as aphids, adelgids, mealybugs, spider mites, thrips, jumping plant lice, scale insects, whiteflies, and sawfly larvae.

Soap Spray
Combining insecticidal soap with water makes a concentrated form of insecticidal soap spray. In order to make the concentrate, grate about 1 inch from a bar of Zote soap, put the grated soap in 1 quart of warm water and stir the water gently until the soap dissolves. The concentrated solution should be stored in a clearly labeled container. When you're ready to spray your plants with an insecticide, place 1 quart of water in a spray bottle or garden sprayer, and add to it 1 teaspoon of the Zote concentrate you made. Don't use a stronger solution. Although insecticidal soap spray is safe for most plants, a high concentration of it may damage plant foliage.

Whitefly damage - worse year so far

Shaving pieces off a bar of Zote

Soap dissolving in the sun

........ Simple video for the idea ......


Kim G said...

Have you tried neem oil? It's very good for aphids and the like and also non-toxic.

Best of luck! The last time I tried to grow tomatoes, it was a race against fungus. As soon as the plant set fruit, the fungus started to attack. Very frustrating, really. I'm not sure if I'm going to try again this year.


Kim G
Boston, MA
Where the red beetles on the lilies are the worst pest.

sparks said...

I've had a few Neem trees and given many away but am not going into production of OIL or anything else they produce.

I'll try the less expensive route and probably have to wait till next year to see

Kim G said...

You can buy the oil already pressed. Making it is probably a huge hassle. Whatever you do, good luck with the bugs!

brad mayeux said...

and without a latin name, this post did nothing to help the confusion....
i google pitaya and all i get is dragonfruit
neither of the plants above

The construction of the house finished in April 2011 and I'm pretty much settled in. As of March 2014 I'm in preparation for rain mode for this coming summer. That includes sealing and painting things and dealing with drainage issues from last year.

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