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Organic Insecticidal Soap Recipes

Posted by Todd_In_Texas Zone 8A Dallas (My Page) on
Wed, Aug 24, 05 at 11:02

Well, I've noticed several leafhoppers (Cicadellidae in the order Hemiptera) on my banana trees for about the past month and they continue to cause damage:

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I've been spot spraying these guys with a safe insecticidal soap and they have been dropping dead. (Click on the thumbnail to read the entire label)

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This spray has been effective but at $4.50 per bottle it is getting a little expensive. How else can I control these guys? Does anyone have a receipe for a homemade insecticical soap? What kind of soap? (Detergent? Non-detergent?) Any name brands of soap to use?

Thanks everyone!

-Todd


Follow-Up Postings:

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RE: Organic Insecticidal Soap Recipes

Why not make a cheap homemade version out of a few tblsp of a mild liquid soap, canola oil, and at least a gallon of water?

Add a little garlic and hot pepper powder if you like for more insecticdal power...


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RE: Organic Insecticidal Soap Recipes

Todd,

FYI, the Targets around here (Arizona) had concentrated bottles of that brand of insecticidal soap for 75% off. I think I paid around $2.25 for it. Not sure if they'll have the same deal in your area but the next time you're in a Target you may want to check it out.

The stuff has helped to control white flies on both my tomato and hibiscus plants. I plan on trying one of these homemade recipes once I run out of this stuff.

Wade


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RE: Organic Insecticidal Soap Recipes

The recipe for Insecticidal soap is 1 teaspoon of real soap, not a detergent, in 1 quart of water. You only need about 1 percent soap solution to be effective and you do not need oil or anything else. What makes the insecticidal soap effective is the fatty acids from the animal fats the soap is made from which is why you need real soap and not a detergent. Those fatty acids disolve the target insects exoskeleton so the dehydrate.


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RE: Organic Insecticidal Soap Recipes

Kimmsr
That makes sense since the label of the spray I'm using now is just 1% "Potassium Salts of Fatty Acids".

Can you tell me where I can find that kind of "real soap" and not a detergent? Are there any popular brands out there?


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RE: Organic Insecticidal Soap Recipes

Ivory, Fels Naptha, Dr. Bronners. There are probably others you would just need to look closely at the labels to see what is in that product.


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RE: Organic Insecticidal Soap Recipes

sooooo... according to what kimmsr said, you would have to spray directly on the hopper...the ones i have are too fast..so how could this work?bz


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RE: Organic Insecticidal Soap Recipes

Hi Todd-You can find Dr. Bronner's at Herb Mart in Mesquite. It's at the corner of Galloway and Town East Blvd. in the same shopping center as The Dusty Attic. That's where I get Dr. Bronner's Sal Suds for all my homemade cleaners.


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RE: Organic Insecticidal Soap Recipes

Insecticidal soaps must come into contact with the insect in order to do the job. Apply the product in the early morning or late afternoon so that it can remain wet for a longer period of time. All the insect has to do is to get a little on him.


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RE: Organic Insecticidal Soap Recipes

I have some Palmolive "Hand Soap" here at home. Can I use that? I don't believe that's a "detergent" so it would work right?

All it says on the label is "Hand Soap" and "Dishwashing Liquid". Is does not say anything about being a detergent.

Well, I just looked up the definition for "detergent" and it says: A cleansing substance that acts similarly to soap but is made from chemical compounds rather than fats and lye.

So I guess that won't work since the back label says something like Tricolsan, Ammonium C12-15.

Thank you all for your suggestions for concentrated bottles, the garlic and peppers..., Ivory, Fels Naptha, Dr. Bronners as well as the Herb Mart refernece here in Mesquite. I'll look for some of those this weekend.

-Todd


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RE: Organic Insecticidal Soap Recipes

You can also use Ivory liquid soap, it is easy to find. I personally use Dr. Bronners though since I use it for so many other things anyway.
Kimmsr Said
"You only need about 1 percent soap solution to be effective and you do not need oil or anything else"
This is true... nothing else is needed, however using a veg oil in the mix makes it last longer since the water will evaporate. This is why Rodale's books as well as many other organic gardening books recommend the addition of oil to many home made solutions. This is also why it is included on the organicgardeningweb.com.
Mixing without the oil is much easier though. You really have to shake the oil up, I use a mason jar.
Sincerely,
SB


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RE: Organic Insecticidal Soap Recipes

I had no idea what two of the products mentioned looked like so I did some research online and found a couple images of them. Of course once I saw the Fels Naptha soap I know I've seen that in my mother and grandmother's laundry room many many times:

But here are some pics incase anyone wants to see what they look like so they can find them easier while shopping:

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Here's what they said about Fels Naptha:

"After 100 years, Fels Naptha Soap is still used everyday in hundreds of households for everything from poison ivy treatment, garden fertilizer and insecticide as well as laundry detergent to stain removal."

and... "...use it as a general cleaner for floors, tubs and showers, or dissolve it in water and spray as an insecticide in the garden."

Here's what they said about Dr. Bronners:

"As a preventative mix 1 tablespoon Dr Bronner's Peppermint soap per quart water. Spray on vegetables on a regular bases or first sign of trouble. On specific pests mix 5 tablespoons per quart water. Test first on plant/bug to see if it is too strong or not strong enough."

Great info! Thanks everyone.

-Todd


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RE: Organic Insecticidal Soap Recipes

A note for vegetarians: Kimmsr wrote, "What makes the insecticidal soap effective is the fatty acids from the animal fats the soap is made from which is why you need real soap and not a detergent." My bottle of Dr. Bronner Pure-Castile Soap is labeled 100% Vegetarian and made from coconut, olive, hemp, and jojoba oils. No animal fats in the product. I don't know about the rest of the soaps.


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RE: Organic Insecticidal Soap Recipes

I would just keep the Bronner peppermint around for your insects tho, If you get it in your eyes, or anywhere else sensitive (yeah, ouch), it stings!

Good thread everyone, its easy, fun, and cheap to make safe household cleaners and garden products (dilute Vinegar stinks for a few mins, but works as well as national brand glass cleaner)


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RE: Organic Insecticidal Soap Recipes

Interresting comment about Dr Bronners... thanks Todd.
That got me to thinking about the fire ant problem I have in my garden... they hate mint... but love my eggplants. Next year I will try Dr Bronners peppermint soap on them and see if it works... anyone tried this?

I used the DrB's peppermint soap for 2 years (now I get free rejects from a friend who makes soap), I had no complaints... but it got cold in the winter. It the texas summers it was very refreshing. My wife doesn't like it though. if I ever loose my fre supply... it will be my soap of choice... it can be a very effective body soap at high dilutions.

SB


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RE: Organic Insecticidal Soap Recipes

Orginut
I'm not sure if this link helps but I found it today and gives instructions on how to use Dr Bronners Soap... like on ants, on tree, on roses, on veggies...
-Todd

Here is a link that might be useful: How to Use Dr Bronners Soap


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RE: Organic Insecticidal Soap Recipes

I didn't make it out to make any special purchases this weekend but I did pick up some Ivory. Here are pics of the front and back label. This is real soap I assume right? I could probably use this as well. Am I right?

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-Todd


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RE: Organic Insecticidal Soap Recipes

I have a Gilmour hose end sprayer. The type that you add the chemical and it dilutes it as it's sprayed. I have a lot of area to cover. Is there a way to convert this recipe to use in my hose end sprayer?


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RE: Organic Insecticidal Soap Recipes

mzpatti, why would you want to spray an insect toxin over a broad area?

Soap is one of the most toxic substances to wildlife there is. It is deadly not only on many insects, but to aquatic organisms as well.

RoundUp is an often criticised 'chemical' product, but what many don't seem aware of is it isn't the chemicals in Roundup that present the primary environmental concern, but the surfactant in RoundUp. The surfactant is simply soap.

Yes, we take it for granted as we use it on ourselves all the time and think nothing of it, but soap should not be indiscriminately applied over large areas by those wishing to garden in an environmentally friendly manner.

To be effective the soap must contact the target organism so a more focused application is usually in order.

Sorry to sound preachy.


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RE: Organic Insecticidal Soap Recipes

  • Posted by farkee 10 B South Fl. (My Page) on
    Wed, Apr 12, 06 at 16:02

mzpatti, I agree with username. Not sure if you have specifically ID'ed an insect problem but ,first of all, alot of times nothing needs to be done as the threshold of damage is minor, secondly, if you do ID an insect and decide to spray only spray on the particular plant the insect is on. Insecticidal soaps do impact some beneficials so should not be used to spray the 'whole' yard but at least they do not have a long residual effect that many chemical sprays have.


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RE: Organic Insecticidal Soap Recipes

"Not sure if you have specifically ID'ed an insect problem but ..."

Perhaps you didn't read the opening post, the one with the picture of a leafhopper, another picture of the damage that has been done, the text which says Todd has been spot spraying, before you jumped in to agree with the ridiculous post preceeding yours?


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RE: Organic Insecticidal Soap Recipes+

Oops! Never mind. Still, the RU post is ridiculous.


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RE: Organic Insecticidal Soap Recipes

  • Posted by farkee 10 B South Fl. (My Page) on
    Thu, Apr 13, 06 at 22:22

Althea, your "oops! Never mind." doesn't cut it with me.

Also don't understand your beef about the post proceeding mine. They were addressing mzpatti who was thinking about using a hose-end sprayer to broadly apply insecticidal soap. It is a very measured and thoughtful reply. Find it amazing you would consider it 'ridiculous' while your own half-baked criticizing posts really leave you with no credibility.


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RE: Organic Insecticidal Soap Recipes

Insecticidal soap srpays are not meant to be used as, and should not be used as, general purpose over the whole garden sprays. No insecticde should be used in that way. Target the pest, not your whole environment.
Dr. Bonners works because of the peppermint oils in it. Slightly different than real soap but almost as effective.


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RE: Organic Insecticidal Soap Recipes

Garden Safe insecticidal soap is very good to kill the aphids on contact. Garden safe has other product to kill aphids on contact but insecticidal soap is the best as I have tested out. I heard more about Neem oil but I have not tried yet. I think the best of killing aphids is lady bug larvae. I see these larvae making aphids on the run and not staying on your pepper tree at all.

LT


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RE: Organic Insecticidal Soap Recipes

Has anyone mentioned that hard water renders insecticidal soap ineffective?


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RE: Organic Insecticidal Soap Recipes

Ivory Liquid is not soap and should not be used for insecticidal soap.

This from Proctor and Gamble's web site (Ivory Liquid is not soap):

Ivory Liquid - (Introduced 1957) - Liquid Ivory for dishes is a light-duty detergent. It earns the Ivory name by offering mildness to hands. Ivory Liquid is "Tough on grease and easy on hands." In 1995, Ultra Ivory Dishwashing Liquid was introduced. Ultra Ivory is still "Tough on grease, easy on hands," while using 1/3 less product than with regular dishwashing detergents.

Here is a link that might be useful: P&G Our History


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RE: Organic Insecticidal Soap Recipes

Use Entrust instead...it is orgainc certified and works. Or try some dishsoap which really simply suffocate the pest...the word "soap" is a mis nomer as is "gluten" in corn gluten meal...


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RE: Organic Insecticidal Soap Recipes

You need to use soap that is made with animal fat and lye.This is real soap. With the soap being made with animal fat you don't have to add any other oil to it


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RE: Organic Insecticidal Soap Recipes

I have many evergreen plants in my yard and every year I fight spider mites. I have been using the "Garden Safe" brand (mentioned above, by Todd) insecticidal soap to keep them at bay, though it needs to be re-applied many times throughout the growing season. This is proving to be very expensive because of the many plants that get infested.

My question is this,
my tomato plants are next to several of these evergreens, and are often covered in the spider mites, as well. Are any/all of these home made recipes safe for use on these tomato plants, and can I use them directly on the tomatoes themselves and still eat them?


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RE: Organic Insecticidal Soap Recipes

I tried a spray with garlic and I'm glad I tested it because it burned the brussel sprout, bean, and tomato leaves that I tested it on. I was just trying it out because I wanted to have it handy if things got out of hand (I have some damage, but don't plan to step in until needed, such as in the case of my poor brussel sprouts which were decimated over the course of 2 days :( ).

I've read that Murphy's Oil Soap makes a decent insecticidal spray and there are also a lot of references to using Bronner's peppermint soap as well.


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RE: Organic Insecticidal Soap Recipes

Ooooh... So Dr. Bronners is Castile Soap, as I see by the photo -Thanks Todd. Now I get why I thought Safer's Insecticidal Soap smells like Castile Soap. It IS castile soap.
I always think of castile soap as a really nice, clean smelling soap that is very mild on skin. (I've used it for various pet situations - it's safe enough for babies, even.)
BUT... the Safer's label says it can harm earthworms, so I use it very judiciously, try to avoid getting it into soil by covering it with plastic, just to reduce whatever will inevitably get into the soil as when it rains. I've mostly used it on potted plants.
Safer's label says you can use it "up to day of harvest" so it should be fine on edibles - just rinse!

What else is it good for? Works on whiteflies, I haven't had much success with thrips or aphids....


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RE: Organic Insecticidal Soap is castile soap

On cost of products: The Safer's is concentrated. A small bottle costs around $4.50 last time I bought it, but you can make probably 10 or so spray-bottles-full. so it really beats the price of the Gardener's Insecticidal Soap shown in OP. Dr. Bronners is fairly expensive , too, as I recall - about $6 a bottle? But then you'd get a heck of a lot of dilutions from one bottle... yeah it's probably pretty cheap that way. That may be the most cost effective, but Safer's would be next best way to go...


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RE: Organic Insecticidal Soap Recipes

If you have a Trader Joe's in your area, their liquid soap (castile) is cheaper than Dr. Bronners. TJ's is about $3.50/16oz, Dr.B's almost $9/qt


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RE: Organic Insecticidal Soap Recipes

I've got a few leafhoppers myself, the little buggers are too fast for me to kill by hand. I just can't bring myself to spray anything that might do damage to the plant of effect the taste. The damage is minor (for now). If it becomes a problem, I'll consider the castille soap thing.
I have peppermint oil, I have neem oil, garlic, all that stuff. I'm just concerned about hurting veggie plants, since everything is okay for now. Perhaps I'll try it out on my perennial flower seedlings that are being DEVOURED. Anybody know a recipe for using cold-pressed neem oil?


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RE: Organic Insecticidal Soap Recipes

Here's a link explaining how neem works as an insecticide:
http://www.discoverneem.com/neem-oil-insecticide.html

And information about diy spray vs. commercial: http://www.discoverneem.com/neem-oil-spray.html

The same website has pages about other household uses for neem but I can't back any of the info up - haven't tried it yet.

Plant-Care has a couple articles with practical tips on using neem in gardening:
http://www.plant-care.com/pest-control-without-pesticides.html
http://www.plant-care.com/neem-oil.html

I'd like to see how Dr.B's peppermint and neem work together. Maybe an ounce of each per gallon water.


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RE: Organic Insecticidal Soap Recipes

Well, ya all can try making your soap your self.
Here is a really simple soap recipe

16 oz shortening
2 ounce powder lye, Ace Hardware carries it.
6 ounces distilled water

Now go to this like and see how soap is made.
http://candleandsoap.about.com/od/coldprocesssoapmaking/ss/sscpsoap.htm


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RE: Organic Insecticidal Soap Recipes

Just thought I would put in a plug for store bought 'insecticidal soap'.

It certainly costs more than homemade concoctions, but a little goes a long way and it's formulated to be hard on bugs and easy on plants. That's the primary problem with homemade solutions, they can strip the waxy coating right off plants resulting in damage.

There are animal and plant based formulations available.


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RE: Organic Insecticidal Soap Recipes

Look at the soap labels. Soap is made of Lye, water, and oil.

Lye is Sodium Hydroxide (NaOH)
Natural Oils to make soap are: Palm, Coconut, Tallow, Olive Oil.
So when you mix the Sodium Hydroxide and water, and one of the above oil, you get

Sodium Palmate
Sodium Cocoate
Sodium Tallowate
Sodium Olivate (Castille Soap)

If a petroleum based oil is used, then you get
Sodium lauryl sulfate

Typically store bought soaps will have other stuff in it for fragrance, anti caking, color perservative, coloring (even for white).

Hope this helps.


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RE: Organic Insecticidal Soap Recipes

As JaG has pointed out, there is a significant difference between commercially prepared insecticidal soap and homemade concoctions. One is the consistency of the product - unless working under laboratory conditions, the properties of the homemade formulation may change as the ingredients are not under your control and the proportions only approximate. And most home dish or hand soaps typically used are detergent based (derived from chemical compounds rather than fats and lye) and contain various additives for stability, coloring, fragrance and possibly antibacterial properties. None of those are necessary to insecticidal soap and may very well create phytotoxic reactions with the plants you are intending to treat.

And the other factor which most tend ignore is that unless it is registered and approved by the EPA for that purpose, it is illegal to recommend or prepare any homemade remedies for disease control. A fine and not too important point for most but one to keep in mind.


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RE: Organic Insecticidal Soap Recipes

  • Posted by jean001 z8aPortland, OR (My Page) on
    Mon, Aug 24, 09 at 23:20

A question to OP:

Are you blaming the dried leaf edges of the banana on the leafhopper? If so, that's not what they do. They're sucking pests and you would see small irregular pale spots on the green background.

Better suspects for the dry brown tissue are insufficient water for one or several reasons. Perhaps soil is too dry, water is applied too seldom or in smaller amounts than needed, and/or drying winds.


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RE: Organic Insecticidal Soap Recipes

Please note that insecticidal soaps are the "POTASSIUM salts of fatty acids"....Thus, if you want to make insecticidal soap from scratch, you need to use potassium hydroxide, NOT lye (sodium hydroxide). Simply follow any recipe for making liquid hand soap or castile soap, and use vegetable oil, not shortening (I like canola). You may also want to slightly 'super-fat' the soap by adding slightly more oil than required (maybe 5-10%). This will insure a milder soap.

Then use about a 1% dilution.


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RE: Organic Insecticidal Soap Recipes

I'd like to suggest that the day after spraying with the soap solution that you dust your plants with self rising flour. When the self rising flour gets into the mouth parts of the insect it thickens up, rises, and chokes or starves the insect. If it makes it to the stomach of the insect the gas and swelling the flour produces also kills the insect. I've had great insect control on my vegetable garden here in south west Florida using a combination of soapy water with next day dusting of self rising flour and a spraying with Conserv Naruralyte.
Good Luck!


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RE: Organic Insecticidal Soap Recipes

Wow. I learned so much on this site about insecticides and insects. I've used JR Watkins 'Naturals' plant based cleaners for roses with aphids. The labels says they are are 95% natural, plant based surfactants, some with Rosemary Oil and seem to work well.


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RE: Organic Insecticidal Soap Recipes

Wow, something I assumed and have been told for years is not true. Ivory Liquid is not pure soap! My formula has always been one tablespoon of Ivory or other pure soap + one tablespoon of vegetable oil in one quart of water. Now I will have to change it.
BTW by my calculations one teaspoon/quart = about .5%
one tablespoon/quart = about 1.5%
Most recommendations for insect control with soap or oil call for about 1-2% depending on the pest, the life stage and the weather.


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RE: Organic Insecticidal Soap Recipes

Self rising flour, grits, rice do not swell inside insects any more than they do inside of you and do not chokeor starve the insect, or cause any other harm to the insect.


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RE: Organic Insecticidal Soap Recipes

You can also Murphy oil soap 1 to 2 tablespoons per 1 gal water


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RE: Organic Insecticidal Soap Recipes

All true soaps are made using animal fats or vegetable oils such as olive oil,cocnut and palm oils, during the soap making ptocess the oils and fat go through saponification which is a chemical reaction between the lye and the oils or fats used in the soap. All soap must contain lye...many organic soaps do not list lye (sodium hydroxide) as an ingredient instead they will list "sapoinified oils" such coconut oil,olive oil, palm oil, this is just a fancy way of listing lye as an ingredient without using the word lye or sodium hydroxide. I know this to be true as I am a soap maker. So you will get the needed amount of oil into an insecticidal spray using soaps containing animal or vegetable oils. For those of you who like to add mint to your spray you can steep some pepermint leaves in hot water, strain and cool and use that as the water for your spray.


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RE: Organic Insecticidal Soap Recipes

Sodium Hydroxide will make a hard bar of soap...If you want liquid you need Potassium Hydroxide...and the percentages are different with how much water, oils, and lye that you need. If you make your own soap with the lye, oils, water, etc.... look online for a lye calculator...


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RE: Organic Insecticidal Soap Recipes

Neem oil, ivory soap= done
The neem oil and soap will also help repel for about 7 days. the spray again. It kills aphids instantly and is more repellant then pesticide.


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RE: Organic Insecticidal Soap Recipes

You can easily make gallons of liquid Castile soap by shaving a bar of pure Castile soap into water [either 1/2 gal or gal] and let it soak to form a thick mixture [you dilute as needed to pass through your sprayer.[you can speed the process by using a kitchen electric mixer]

It kills bugs on contact and is gentle. A direct spray, kills Japanese Beetles immediately and wipes out those tiny worms that hide under rose leaves. Adding a bit of pure peppermint oil is supposed to act as a deterrent to insects [and smells good too].


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RE: Organic Insecticidal Soap Recipes

I have a Hibiscus Tree that I had to bring in for the winter. Looks like it has aphids and possibly spider mites and white flies. It still looks pretty healthy but starting to get infested. I plan on taking it outside to spray it well with the soap mixture mentioned here and just wanted some guidance on the frequency. I plan to use plain old ivory bar soap that I have from about 15 years ago - I think the ingredients are sodium tallowate, sodium cocoate or sodium palm kernelate, water, sodium chloride, sodium silicate, magnesium sulfate, and fragrance. So all I need to dissolve some of that soap in water and mix 1t soap to 1 QT water - right? I am on city water - any problem with that?
I also have octagon soap - would that work better? I live in NC and haven't been able to find Fels Naptha here.
Please advise. I want to try to spray this tree tomorrow while the weather is mild.
Thanks


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RE: Organic Insecticidal Soap Recipes

Handywench, If you have white flies, I'd also look into using a dormant oil spray, which *should* kill the tougher life stages.

But to answer your question, if I have to nuke lots of bugs with soap, I try to do it every 4-5 days, total of 3 times.

I see mentioned above using Dr. Bronners peppermint soap - this works pretty well - I use a bit stronger, maybe 2 tablespoons/gallon.

And, your plants smell nice.


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RE: Organic Insecticidal Soap Recipes

I have not seen, in some 60 years of gardening, any Insecticidal Soap that would kill any insect on contact. The Insecticidal Soaps work by disolving the insects exoskeleton and that takes some time to do.
! teaspoon of soap to 1 quart of water, or since there are 3 teaspoons per tablespoon and there are 4 quarts per gallon you will need to mix 4 tablespoons of soap per gallon of water to get the same dilution.
Do not mix a large amount at one time thinking of using it over several days. Mix each batch as needed.


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RE: Organic Insecticidal Soap Recipes

To make the equivalent to Safers, look up a soap-making recipe, use (as mentioned above) POTASSIUM hydroxide (not sodium hydroxide or lye), and use grocery-store lard or your own bacon grease savings to make the soap (i.e., animal fatty acids). Safers may possibly use fish oil (I think I read that once) but that is not as easily obtainable in bulk.

Potassoum hydroxide is available from home-soap-making supply houses.
http://www.chemistrystore.com/

Fels Naptha Soap used to be made with naphtalene (moth ball chemical) but not for a long while ("naptha" itself is more-or-less gasoline, so the name has never been accurate).


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RE: Organic Insecticidal Soap Recipes

I think that what happened with the Ivory soap is that they changed the soap since the time this thread started in 2005. The product was built on a great natural ingredients, then they changed the product. Now I think it even has lotions added.


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RE: Organic Insecticidal Soap Recipes

I have never seen anything listed on the ingrediants label for Fels Naptha soap to indicate that Naphthalene was ever in it. This was a favorite soap of my parents and there was no odor of Naphthalene present even back in the 1950's.

Here is a link that might be useful: Fels Naptha soap ingrediants


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RE: Organic Insecticidal Soap Recipes

Why would anyone expect a label on a current product to say what was in it decades ago?

Googling -- Fels naptha naphthalene -- gives several references mentioning (albeit nonauthoritatively) napthalene as once being an ingredient and another says it was Staddard's Solvent, this being close to mineral spirits or kerosene and thus likely with some napthalene in it.


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RE: Organic Insecticidal Soap Recipes

Insect Control: Soaps and Detergents

by W.S. Cranshaw 1
Quick Facts...
Soaps can be used to control a wide range of plant pests. Small, soft-bodied arthropods such as aphids, mealybugs, psyllids and spider mites are most susceptible to soaps.
The ease of use, safety and selective action of soaps appeal to many people.
Limitations of soaps include the need to wet the insect during application, absence of any residual effectiveness, and potential to damage some plants.
Soaps or detergents used for control of insects are applied as dilute sprays, mixed with water to produce a concentration of about 2 percent.
Soaps have been used to control insects for more than 200 years. Recently, there has been increased interest in and use of these products. This change is due to a better understanding of how to use soaps most effectively and a desire to try insecticides that are easier and safer to use than many currently available alternatives.

How soaps and detergents kill insects is still poorly understood. In most cases, control results from disruption of the cell membranes of the insect. Soaps and detergents may also remove the protective waxes that cover the insect, causing death through excess loss of water.

Soap-Detergent Sprays
Soaps and detergents act strictly as contact insecticides, with no residual effect. To be effective, sprays must be applied directly to and thoroughly cover the insect.

Several insecticidal soaps are distributed for control of insects and mites. Available under a variety of trade names, the active ingredient of all is potassium salt of fatty acids. Soaps are chemically similar to liquid hand soaps. However, there are many features of commercial insecticidal soap products that distinguish them from the dishwashing liquids or soaps that are sometimes substituted. Insecticidal soaps sold for control of insects:

are selected to control insects;
are selected to minimize potential plant injury; and
are of consistent manufacture.
Some household soaps and detergents also make effective insecticides. In particular, certain brands of hand soaps and liquid dishwashing detergents can be effective for this purpose. They are also substantially less expensive. However, there is increased risk of plant injury with these products. They are not designed for use on plants. Dry dish soaps and all clothes-washing detergents are too harsh to be used on plants. Also, many soaps and detergents are poor insecticides. Identifying safe and effective soap-detergent combinations for insect control requires experimentation. Regardless of what product is used, soap-detergent sprays are always applied diluted with water, typically at a concentration of around 2 to 3 percent (Table 1).

Susceptible Insects
Most research with insecticidal soaps and detergents has involved control of plant pests. In general, these sprays are effective against most small, soft-bodied arthropods, such as aphids, young scales, whiteflies, psyllids, mealybugs, and spider mites. Larger insects, such as caterpillars, sawflies and beetle larvae, generally are immune to soap sprays. However, a few large insects, including boxelder bugs and Japanese beetles, are susceptible.

Insecticidal soaps are considered selective insecticides because of their minimal adverse effects on other organisms. Lady beetles, green lacewings, pollinating bees and most other beneficial insects are not very susceptible to soap sprays. Predatory mites, often important in control of spider mites, are an exception: a beneficial group of organisms easily killed by soaps.

Application
One of the most serious potential drawbacks to the use of soap-detergent sprays is their potential to cause plant injury -- their phytotoxicity. Certain plants are sensitive to these sprays and may be seriously injured. For example, most commercial insecticidal soaps list plants such as hawthorn, sweet pea, cherries and plum as being sensitive to soaps. Portulaca and certain tomato varieties also are sometimes damaged by insecticidal soaps. The risk of plant damage is greater with homemade preparations of household soaps or detergents. When in doubt, test soap-detergent sprays for phytotoxicity problems on a small area a day or two before an extensive area is treated.

Plant injury can be reduced by using sprays that are diluted more than the 2 to 3 percent suggested on label instructions. To reduce leaf injury, wash plants within a couple of hours after the application. Limiting the number of soap applications can also be important, as leaf damage can accumulate with repeated exposure.

However, because of the short residual action, repeat applications may be needed at relatively short intervals (four to seven days) to control certain pests, such as spider mites and scale crawlers. Also, application must be thorough and completely wet the pest. This usually means spraying undersides of leaves and other protected sites. Insects that cannot be completely wetted, such as aphids within curled leaves, will not be controlled.

Environmental factors also can affect use of soaps. In particular, soaps (but not synthetic detergents) are affected by the presence of minerals found in hard water, which results in chemical changes producing insoluble soaps (soap scum). Control decreases if hard-water sources are used. Insecticidal soaps may also be more effective if drying is not overly rapid, such as early or late in the day.

Soaps and detergents can offer a relatively safe and easy means to control many insect pests. As with all pesticides, however, there are limitations and hazards associated with their use. Understand these limitations, and carefully follow all label instructions.

Table 1: Approximate mix to produce various dilute soap sprays.
Percent dilution desired Approximate amount of soap to add to water to produce:
Gallon Quart Pint
1 2 1/2 Tbsp (-) 2 tsp (+) 1 tsp (+)
2 5 Tbsp (-) 4 tsp (+) 2 tsp (+)
3 8 Tbsp (+) 2 Tbsp (+) 1 Tbsp (+)
4 10 Tbsp (-) 2 1/2 Tbsp (+) 4 tsp (+)
(+) Will produce a solution of slightly higher concentration than indicated.
(-) Will produce a solution of slightly lower concentration than indicated.

1Colorado State University Extension entomologist and professor, bioagricultural sciences and pest management. 12/96. Reviewed 3/08.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

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Updated Friday, August 03, 2012


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RE: Organic Insecticidal Soap Recipes

Wow, I learned a lot from this thread!

I'm looking for a solution to fungus gnat larvae attacking my indoor plants. I emailed my local Master Gardeners and they recommended (somewhat vaguely) "pesticidal soap" or "horticultural oil."

After reading everyone's posts, I think I'm going to try spraying the store-bought insecticidal soap on the soil (where the offending larvae live)...

...Unless anyone has a better suggestion. I'm open to any advice that can help me get rid of these critters.

~peace~


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RE: Organic Insecticidal Soap Recipes

Knowing something about your enemy helps you conquer them. Fungus Gnats grow in quite moist environments and the simpelest method of control is to allow the growing medium they are in to dry out between waterings.
No reason to douse the growing medium with Insecticidal Soap or any other "something" that most likely will not do a very good job of controlling them anyway.

Here is a link that might be useful: About Fungus Gnats


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RE: Organic Insecticidal Soap Recipes

I sprinkle the potting soil with the crumbly version of "mosquito dunks" (see link) which contain a bacteria that works on fungus gnat larvae.

Very effective.

Here is a link that might be useful: link


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RE: Organic Insecticidal Soap Recipes

Peace, your master gardeners are not well informed.


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