Neem oil

ccabal(7)August 28, 2012

I had purchased some Need oil earlier this year, specifically "Fertilome triple action plus". I have been dissapointed with it, since it has not had much of an effect with my aphids, and has not discouraged any squash vine borer egg laying, and doesn't seem to exhibit the systemic properties I have read about in the web. I've wondered if I had a bad batch, or if its just overrated and not that effective. Today I found this article:

This is very interesting. The aithor explains the difference between real cold-pressed neem oil, and many of the product out there. My bottle says "Clarified hydrophobic extract of neem oil" , so its lacking the Azidaractin !! So maybe my evaluation of neem oil has not been fair! I'll plan on buying a bottle of pure cold-pressed neem oil next and give that a shot.

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The author of that article makes enough erroneous claims about the product to bring eveything written there into question. While Neem Oil products are not toxic to humans to state that they are not toxic to certain insects while killing others stretches the immagination. These may be of somewhat lower toxicity to insects that do not ingest the stuff, beneficial insects still can be harmed by them if they are sprayed at the wrong time or used inapropriately.
Neem oil products are not the magic elixar some proponents of it make it seem, and like all other pesticides they can harm beneficials.

    Bookmark   August 31, 2012 at 6:30AM
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rhizo_1 (North AL) zone 7

Anything can be harmful if sprayed at the wrong time or used inappropriately.

ccbal, avoid the clarified extracts and simply find cold pressed oil. It is READILY available on-line. The product I happen to use is Dyna-Gro, something I keep on hand for occasional pest and disease issues in the veggie garden. It, and most other cold pressed neem products, are 70% neem though Dyna-Gro also manufactures a 100% neem oil product with directions about how much soap to add to make an emulsion.

Please know that the use of this and any other product you may decide to use in your organic garden comes with responsibilities. It's always important to remind ourselves about how to use a product properly so that unintentional harm does not occur to non-target critters as well as to the plants we are trying to protect.

Good luck and don't hesitate to ask if you have any questions. Neem oil is a fabulous tool for the organic gardener but not effective on every problem. Nothing is, right? ;-)

    Bookmark   August 31, 2012 at 1:02PM
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tapla (mid-MI z5b-6a)

From another thread:

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Posted by kimmsr 4a/5b-MI (My Page) on Mon, Jun 1, 09 at 20:53

Everything I have read about Neem Oil products states that they are broad spectrum poisons, they kill insects on contact and through ingestion. Some of these sources state that there is nothing to indicate these products harm beneficials, but that no studies have been done to see if there may be harm to beneficials. I have yet to find a pesticide that only kills insect pests and does not harm beneficial. How would this product know that this insect is not to be killed? Does the beneficial insect have some kind of ID tag to tell the Neem Oil not to kill it?
If you use Neem Oil products, or any other pesticide, read and follow the label directions carefully. However the objective of an organic gardener should be to not have to use any pesticide.

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Posted by organicguy (My Page) on Mon, Jun 1, 09 at 21:42

I have never seen it claimed anywhere that Neem kills anything on contact. It is effective against many types of insects, including LEAF MINERS!! Here is some accurate information put out by Cornell Cooporative Extension on Neem, how it works and what it is effective against -
Neem oil. Another group of neem products is made from the oil fraction of neem extract. The
active ingredient is generally listed as "clarified hydrophobic extract of neem oil," and is labeled
as a fungicide, insecticide, and/or miticide. Insects and mites susceptible to paraffinic
(petroleum-derived) horticultural oil are likely to be controlled to some extent by neem oil
products. The mode of action is probably similar to other oils, namely membrane or cuticle
Every effort has been made to provide correct, complete, and up-to-date pesticide recommendations. Nevertheless, changes
in pesticide regulations occur constantly, and human errors are still possible. These recommendations are not a substitute for
pesticide labeling. Please read the label before applying any pesticide. The information given herein is supplied with the
understanding that no discrimination is intended and no endorsement by Cornell Cooperative Extension is implied.
This document is a product of the Landscape Horticulture Program Work Team at Cornell University. Primary contributors include Paul
Weston, Department of Entomology and Dan Gilrein, Cornell Cooperative Extension, Suffolk County. Prepared June, 2007
disruption and/or interference with respiration. Note that the activity is distinct from that of
azadiractin-based insecticides.
Other neem products. In addition to products based on azadirachtin or neem oil, there are also
other pesticides derived from neem. One such product, K+ Neem, is an insecticidal soap made
from neem oil, listed on the label as potassium salts of fatty acids. Mode of action (membrane
disruption) and efficacy against arthropods is probably similar to that of other insecticidal soaps
since the product has no measurable quantities of azadirachtin.
What does neem control?
Although neem has a fairly broad spectrum of activity against insects, some insects are more
susceptible than others, and results often vary from pest to pest. Many leaf-feeding larvae are
susceptible to azadirachtin-based products; this list includes lepidopterous larvae (caterpillars), leaffeeding
beetle larvae, and sawflies. [NOTE: we have not seen significant efficacy against viburnum
leaf beetle larvae.] Fluid-feeding insects such as aphids, leafhoppers, and plant bugs are also fairly
well controlled by products based on azadirachtin, as are dipterous leaf miners and fungus gnats.
Adults of a number of insect groups are also responsive to azadirachtin; Japanese beetles and
grasshoppers reportedly avoid neem-treated foliage. Neem-oil products are reportedly effective
against aphids, whiteflies, scale crawlers, and spider mites. Neem products are generally not
effective against mealybugs, weevils, thrips, or adult scales. Use of neem products against pests not
on the label is not advisable because efficacy against these pests has not been determined (or is
inadequate), not to mention the fact that such uses are illegal in New York.

Here is more info from another reliable website -

How Neem Oil Works:
According to the EPA, "Azadirachtin and Clarified Hydrophobic Extract of Neem Oil are derived from the natural oil found in seeds of the neem tree.... When the natural neem oil is removed from the seeds and treated with alcohol, virtually all of the azadirachtin and related substances separate from the oil itself. The remaining oil - without the azadirachtin - is called Clarified Hydrophobic Extract of Neem Oil. Azadirachtin acts in the following ways: It deters certain insects, such as locusts, from feeding and it interferes with the normal life cycle of insects, including feeding, molting, mating, and egg laying."

Neem Oil As Organic Insecticide: Pests Killed or Repelled:
Neem oil kills some pests (after they've eaten leaves sprayed with neem oil), while it repels others with its strong smell. Neem oil is used to control many pests, including whitefly, aphids, Japanese beetles, moth larvae, scale and spider mites. Because it kills mites -- which aren't insects but, instead, related to spiders and ticks -- neem oil is listed as a "miticide." Sprays containing clarified hydrophobic extract of neem oil are also used as fungicides against rust, black spot, mildew, leaf spot, scab, anthracnose, blight and botrytis.

Benefits of Neem Oil for Pest Control:
Besides being an organic insecticide, using neem oil allows you to target pests, specifically, as opposed to beneficial insects (e.g., bees and lady bugs). By definition, "pests" are the insects eating your plants, and neem oil, properly applied, kills an insect only if it ingests the sprayed foliage (bees and lady bugs don't eat plant leaves).

The Garden Guy
Informative articles, ongoing garden journal and
interactive message boards.

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Posted by justaguy2 5 (My Page) on Mon, Jun 1, 09 at 22:00

Everything I have read about Neem Oil products states that they are broad spectrum poisons, they kill insects on contact and through ingestion.
You posted a link in the other neem thread that indicated it doesn't kill on contact other than the same way any horticultural oil might on soft bodied insects like aphids.

You have seen posted here information on it's harmlessness to bees unless sprayed directly on them and even then it isn't anywhere near a 100% kill. Info has been posted in threads you have participated in indicating that even bees collecting pollen of sprayed flowers aren't killed. You have seen information here about honey bee keepers spraying their hives with neem.

You have seen here info from credible sources indicating lady bugs aren't harmed by it.

It has been explained to you numerous times by numerous people precisely what science has to say about neem.

Yet you continue to describe it as if it was Sevin.

Let's be very clear on this:

Neem may kill soft bodied insects that it is sprayed directly onto. Neem may kill insects that ingest plant material sprayed with it.

Other than that neem appears to be pretty benign to everything else. Humans ingest the stuff. It's used in health care products. Neem is one of the safest, least toxic pesticides that is actually effective against a variety of common plant pests.

Describing it as a 'broad spectrum, on contact' pesticide makes it sound like Sevin which it is not.

So, do you *now* understand what neem is and what it is/isn't toxic to?

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Posted by gardengal48 PNW zone 8 (My Page) on Mon, Jun 1, 09 at 22:23

There ARE targeted insecticides.....those that only direct their effectiveness at specific insects or insect types. Bacillus thuringiensis (Bt) is a common example, milky spore is another. While neem does have a much wider target base than either of these two examples, it IS a directed insecticide, targeting primarily sucking and chewing insects - aphids, spider mites, mealy bugs, scale, etc. Since the beneficial insects like ladybugs, ladybug larvae, mantises, parasitic wasps, bees and butterflies are not classified as sucking or chewing insects and tend to feed on other insects or on non-plant parts, like pollen, the neem poses a minimal threat to them. And there have been tests/studies done to confirm that this is the case......if one bothers to do the research, it's not all that difficult to find.
Depending on how the neem is applied, it can have a systemic effect - that is, it is transmitted into the plant tissues. Generally this is accomplished when used as a soil drench, as opposed to just spraying it on the foliage. The effect will be longer lasting when applied in this manner compared to the more common spray method. It is also found to have some deterrent qualities when used in this manner, discouraging some insects (the primary tests involved grasshoppers) from eating the treated plants at all.

The effectiveness of neem is not immediate. Because of its course of action - essentially hormonal disruption - it often takes some time to see clear evidence of its effectiveness. It takes time for those insect digestive systems to breakdown, or for them stop to laying eggs. It is not the immediate knockdown, kill everything, broad spectrum 'poison' some seem to think. But it IS effective and it IS pretty darn benign.

Those who persist in stating otherwise - i.e., that it is a non-effective, broad spectrum contact insecticide that will harm beneficials - do not have a good understanding of the product or how it works. Then again, I'm not sure they have much of an understanding of how ANY specific pesticide works :-)

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Posted by tapla z5b-6a MI (My Page) on Tue, Jun 2, 09 at 14:35

It is indeed wearisome to hear the same things rigidly offered over and over again. "You can't do this or that and belong to the good organic gardener's club - your goals should be .... well, they should be MY goals - the cure to everything under the sun is to add more organic matter to the soil.
Incessantly pursuing dogmatic offerings in the face of an assortment of reasonable alternatives is not what posters here want to read. They don't come here to be preached to, but to gather useful suggestions and ideas so they can evaluate them for themselves. Telling them what they can and can't do, or what they should and shouldn't do is an affront to any individual's ability to make their own decisions or to reason through a problem on their own.

Neem's scope of effectiveness is concentrated heavily on those insects with rasping and sucking mouth parts - the ones that feed on plant saps. Tertiary mortality of non-target species is EXTREMELY low. If you have an absolute '0' tolerance for any impact whatsoever on beneficial populations of insects and bugs, then avoid all insecticides, because there are none that will ONLY kill targeted species. If you personally decide you NEED an insecticide today (not in three years after your soil has been made healthier via the inclusion of more organic matter, and your plants are bursting with vim and vitality), then neem oil is one of the very safest choices you can make.


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Posted by organicguy (My Page) on Tue, Jun 2, 09 at 14:48

Al and Just A Guy,
You hit a homerun! The "fanatics" that are against everything and anything are what make organic gardeners look like kooks to some.
There are great completely organic products available that make organic gardening not only work, but practical and productive. To put these products into the category of toxic chemicals is not only uninformed abut irresponsible.

My goal in over 50 years or organic gardening and farming has always been to keep as much toxic chemicals as possible out of my food and enviroments, while at the same time enjoying my garden, nature and the art of gardening itself. If I have to occasionally kill a beneficial to save a crop, I have no problem with that, because my healthy soil and crops soon attract many more to take their place.

The Garden Guy
Informative articles, ongoing garden journal and
interactive message boards - All FREE!

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Posted by tapla z5b-6a MI (My Page) on Tue, Jun 2, 09 at 15:29

Exactly - try as hard as you can, you/we still may find ourselves in a situation where we feel we need to use a product we might not normally use, and I'm not necessarily referring to neem oil, because it IS so innocuous. Reasonable people understand this and adjust. We can't tout the principles of IPM in one breath and eliminate the possible use of every insecticide known to man in the next and expect retain credibility.

I've been a member of GW for a good number of years, and I used to visit this forum regularly, but I found myself constantly entrenched against the same one or two vocal individuals with extremely narrow perspectives about what was or wasn't a good garden practice. I just grew weary of it, choosing to only pass through occasionally (though I've spent a little more time here lately) and to look elsewhere for my fun.



More about Neem oil - something I wrote years ago:

Neem Extract as an Insecticidecolor>size>

In India mainly, but also Asia and Africa, grows a tree all plant enthusiasts should be aware of, Azadirachta indica, commonly known as the "neem" tree and a relative of mahogany. Extracts from the tree's seeds contain azadirachtin, a relatively safe and effective naturally occurring organic insecticide. Let me preface the comments following by reminding you that the terms "naturally occurring and/or organic" do not universally mean safe. Pyrethrums, rotenone, and even the very dangerous nicotine are all organic insecticides that should be handled with great caution. Neem extracts, on the other hand are very safely used in a wide variety of cosmetics, as a topical treatment for minor wounds, as an insecticide in grain storage containers, bins, and bags, and a whole host of other applications. Neem is very safe for use around birds & mammals. I'll limit this discussion to its use as an insecticide.

Neem works in many ways. It is effective both in topical and a systemic applications. It is an anti-feedant, an oviposition deterrent (anti-egg laying), a growth inhibitor, a mating disrupter, and a chemosterilizer. Azadirachtin, a tetranortriterpenoid compound, closely mimics the hormone ecdysone, which is necessary for reproduction in insects. When present, it takes the place of the real hormone and thus disrupts not only the feeding process, but the metamorphic transition as well by disrupting molting. It interferes with the formation of chitin (insect 'skin') and stops pupation in larvae, thus short-circuiting the insect life cycle. It also inhibits flight ability, helping stop insect spread geographically

Tests have shown that azadirachtin is effective in some cases at concentrations as low as 1 ppm, but some producers use alcohol or steam in the extraction of neem oil from plant parts, which causes the azadirachtin to be removed from the oil or diminishes the amount of azadirachtin in the product as well as its effectyiveness. Some products touting neem oil as an ingredient actually have no measurable amounts of azadiractin. I use what is referred to either as cold pressed or virgin neem oil. You may also occasionally find it referred to as 'raw' or 'crude' neem oil.

Neem oil is most often used in an aqueous (water) suspension or emulsion as a foliar spray or soil drench. Commonly, it is diluted to about a .5 to 2% solution, but the suggested ratio for use in container plant culture is 1 tsp. per quart of warm water. A drop or two of dish soap (Castile, olive oil, or Murphy's Oil soap work better) helps keep the oil emulsified. The mixture is then applied as a mist/spritz to all leaf and bark surfaces and as a soil drench to the tree's root system. It should not be applied as a foliar spray on hot days or in bright sun as leaf burn may occur. Remember to agitate the container frequently as you apply and do not mix any more than you will use in one day. Neem breaks down rapidly in water and/ or sunlight.

Some users of insecticides feel the need to observe the instant results of their efforts in order to be convinced of the effectiveness of what they are using. The application of neem derivatives does not provide this immediate gratification. There is virtually no knockdown (instant death) factor associated with its use. Insects ingesting or contacting neem usually take about 3 - 14 days to die. Its greatest benefit; however, is in preventing the occurrence of future generations. It is also interesting to note that in studies it was found that when doses were given, purposefully insufficient to cause death or complete disruption of the metamorphic cycle, up to 30 surviving generations showed virtually no resistance/ immunity to normal lethal doses, so it appears that insects build no 'resistance' to azadiractin.

I have been using neem oil for more than 15 years as an effective preventative and fixative. Applications of cold-pressed neem oil are most effective for use on mites, whitefly, aphids, thrips, fungus gnats, caterpillars, beetles, mealy bugs, leaf miners, g-moth, and others. It seems to be fairly specific in attacking insects with piercing or rasping mouth parts, and since these are the pests that feed on plant tissues, they are our main target species. Unless beneficial like spiders, lady beetles, certain wasps, etc., come in direct contact with spray, it does little to diminish their numbers.

Neem oil does have an odor that might be described as similar to that of an old onion, so you may wish to test it first, if you intend to use it indoors. I've found the odor dissipates in a day or two. As always, read and follow label instructions carefully.

Neem oil can be purchased from many net or local sources. My favorite brand is Dyna-Gro, pure, cold-pressed neem oil. If you have trouble locating a source, you can contact me via the forum or directly.


    Bookmark   September 10, 2012 at 5:56PM
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Man WHAT A SCAM out there with Neem products.. This should be illegal or false advertising.. So what I bought thinking was the real deal was the "clarified hydrophobic extract" which had the main active ingredient I needed removed from it!! That ticks me off.. Then they sold the actual azidaractin as a separate product. I read about how good neem is, but I guess what they are talking about is the real stuff with azidaractin,and I was left with a dud. No wonder what I had was ineffective. The aphids were unaffected, and I got just as many SVB laying eggs and attacking my squash plants. I was going to write off Neem as a dud, but I guess now I need to give the real stuff a chance.

    Bookmark   September 11, 2012 at 12:12AM
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I would note that with Neem oil, despite claims to the contrary, that direct contact with a drenching spray on beneficial insects is likely to be death to those beneficial insects. It would be disruptive to the maturation process to those which survive the suffocation that many vegetable oils, even canola oil (much cheaper than Neem, if that is all that you want to do), so your beneficial wasps, flies, and beneficial mites will be of less use to you in an integrated pest management system. Before you use a whole Neem product (this excludes the nearly totally ineffective clarified Neem products from which the azadirachtin has been removed, and so is mainly useful to shine leaves or smother some insects), do some research to find out from someone other than some of the popular organic gardening charlatans (many are not charlatans) who hold forth from radio forums and endorse products they've been paid to endorse, if Neem is efffective on something that is infesting your garden. How was that for a run-on sentence? If you have an integrated pest management system, healthy soils, and don't have a rogue neighbor with unabated pests in a neighboring field, then you likely don't need Neem oil in your garden or greenhouse.

    Bookmark   August 14, 2013 at 12:04AM
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