Saturday, June 26, 2010


Neem is an effective organic insecticide that can help control a wide variety of garden insect pests and powdery mildew. However, because it is relatively strong, gardeners should understand how it works and time its use carefully. Keep the beneficial insects around and do away only with the pests by using neem wisely.


  1. Neem is a botanical insecticide made by extracting oil from the seeds of the neem tree. The neem tree is native to the Indian subcontinent, where it has been used for many purposes, including garden applications, spermicide and toothbrushes. Neem oil is used by gardeners to kill insects and is considered an organic insecticide.
  2. Types

  3. Neem is typically sold as one ingredient in organic insecticidal sprays that may include other organic compounds for optimum pest control. Some of these might be sold as concentrates that are then diluted for use in the garden. Another possibility is to buy pure neem oil and mix your own customized spray for the garden.
  4. Function

  5. Neem can be used to control a variety of garden insect pests. Aphids can be killed by spraying neem oil mixed into water on the top and bottom surfaces of leaves. Stink bugs, leaf-footed bugs and squash bugs are also potential victims for neem. Spider mites--most often seen on tomato plants--are also targets for neem. Finally, neem can help control powdery mildew on plants.
  6. Time Frame

  7. Because neem is an organic insecticide, its residue will last for a shorter time in the garden than that of other, stronger products. It also does not enter plants' systems as extensively as other chemicals. This means you need to apply neem more frequently than other insecticides. The exact interval for applications will depend on the severity of your insect infestation. You can spray it as often as you wish to control the number of bugs in the garden. Keep in mind, though, that it may take up to a week to see a reduction in the insect population after the first application of neem; give it time to work.
  8. Warning

  9. Although neem is an effective organic insecticide, it is almost too effective to use frequently in your garden. Neem is not selective in the insects it kills, and it will affect both the insect pests and the beneficial insects that reside in your garden. If you want to maintain a well-balanced organic garden, you'll want to make sure it's a friendly place for those beneficial insects. Before resorting to neem, try using other organic pest control methods, including hand-picking insects off plants and using row covers to keep pests from landing in the first place. However, if the bugs are out of control, use neem wisely to reclaim your garden.


Neem extracts are particularly suitable for use on vegetables and small scale field crops. If sufficient water and sprayers are available it is also possible to treat larger fields.


Numerous insect species are repelled by active ingredients in the neem seed. As they find the taste and smell unpleasant they avoid the plants that have been treated with neem extracts. Other insects die some time after having eaten leaves or other parts of the plant treated with these substances. They alter the behaviour in some insects or reduce their ability to lay eggs. Other pest species are affected minimally or not at all by the neem substances, probably as a result of their hidden biology.


The neem extract can be applied in two ways: When using a sprayer, the rough particles must first be filtered out of the mixture to prevent clogging the nozzle. This is done by covering a bucket or similar container with a coarse cloth or gauze through which the mixture is poured. The sprayer is filled with the filtered solution and spraying of the vegetable crops can begin.

If no sprayer is available the extract may be applied with a straw brush. In this case, it need not be filtered. A brush made with fine, flexible straw is simply dipped into the solution and shaken over the plants until all the leaves are moistened. The effect of the neem substance lasts between 3 to 6 days, regardless of how it was applied.


If and when spraying is necessary depends very much on the individual case and this can only be decided by the farmers or the appointed adviser. In general, it may be said that in areas of vegetable cultivation, where pests are a great problem, weekly spraying is necessary. If, on the other hand, infestation is only slight, treatments in intervals of 10 to 14 days are adequate. Often a single treatment of the plants is sufficient. Just as with chemical insecticides, the insect species and crop are important factors in deciding how often spraying should occur. According to scientific research the extract is not poisonous for humans, thus, it is not necessary to wait long between final spraying and harvesting.


The neem extract does not have the same effect on all insect species. Some pest groups can be easily controlled. The feeding behaviour of other groups may be influenced or their ability to reproduce impaired, but this does not prevent direct damage to the plants. Some insects react minimally or not at all to the extracts.

Given below you will find more detailed information on the reactions of pests of neem extracts. It is important to note, however, that this is not intended as a precise description of the effects of neem extracts but as a guide which gives the user advice as to which pests may be controlled by application of neem.


Stem borers on young corn and sorghum plants can be controlled relatively easily with crushed neem seeds (the powder normally used to mix with water). A small amount of powder mixed with sawdust or dry clay at a ration of 1:1 is placed in the funnel. 1 kg powder should be sufficient for 1500 - 2000 plants.

In this method, rainwater dissolves the substances in the neem seeds as it gathers in the funnel and washes out the powder. Where rainfall is irregular a liquid neem seed extract can be sprayed into the funnel.

This treatment should be repeated every 8 to 10 days during the sensitive growing phase. Thus, roughly three treatments are sufficient for protection against stem borers. This recommendation applies only for young plants before flowering and not for older plants.


Stored grain legumes can easily be infested with bruchids. These are small beetles whose larvae eat into the grain. The bruchids can be controlled simply by mixing the legumes with neem oil.

Neem oil is extracted from the neem seed kernels (oil content 40 – 50%). When used for storage protection it should be carefully pressed, either by machine or various other traditional methods. As only a very small amount of oil (30 ml oil per 100 kg grain) is required, pressing by hand is practicable. The seeds must first be shelled, by cracking the shells with a stone or gently pounding in a mortar and finally by winnowing to remove the shell particles.

If the crushed seeds are very hard and brittle they should be moistened and left to stand for several hours until they can be pressed together by hand. Crushing the seeds in a mill or mortar produces a rough, sticky mixture out of which can be pressed by kneading. Usually it is necessary to add a little water to make kneading easier.

By alternating kneading and pressing of the paste in a bowl the neem oil is released. Using this method it is possible to extract 150 ml oil from 1 kg powder. The legume seeds are treated with neem oil extracted in the following manner: The appropriate amount of neem oil is mixed with the legume seeds in a large bowl or similar container (3 ml per 1 kg grain); then the seeds may be stored in the usual way.

Neem oil is non-poisonous but very bitter, thus freshly treated legumes taste at first very sharp. This taste disappears, however, after 3 to 4 weeks


Apart from its previously described application for storage protection, neem oil has been a trusted remedy for a naturally healthy skin in the villages of India. Derived from the seeds of the neem tree it contains all the disinfecting and healing properties of the tree, in a concentrated easily usable form. For centuries, this therapeutic oil has provided protection and

Scientific studies have shown that Neem contains certain chemicals, which are unique. The primary chemicals are a mixture of 3-4 related compounds called limonoids. Neem seeds also contain a few chemicals that have sulphur. These phyto-chemicals add the characteristic smell to the neem oil. They also attach additional curative properties to the oil. It has a dark yellow color, turns solid at temperatures below twenty-three degrees Celsius, and does not dry out. The oil is composed mainly of glycerides of palmitin, stearin, oil and linol acids. It chemically resembles soy oil or olive oil. In the cold-pressed oil, there are also 10 to 20 percent of the total content of biologically active components, especially the limonoids. Bitter components contained in neem oil and certain sulfur compounds that give the oil its strong garlic scent, destroy the taste.

It is a completely natural total first aid tool for families. Due to its unique composition it has an almost magical effect on chronic skin conditions that fail to respond to conventional treatments. What makes neem oil outstanding in comparison to other remedies is that it is active against all three varieties of infectious organisms: Bacteria, Fungii and Viruses. The oil is known to provide a very effective germicidal action. Modern science has now confirmed the effectiveness of Neem oil in fighting infection. Scientific studies indicate that Neem has very powerful skin rejuvenating qualities and it is being hailed as the Oil of Wonder.

Many strains of bacteria are found to be resistant to the modern antibiotics. Neem oil has a seemingly endless range of antibacterial uses. This has prompted the development of neem as an anti-bacterial drug for these resistant strains, against which it has shown promising activity in the laboratory tests. Because of its antiseptic qualities, neem oil is also well suited for medicinal soaps and pharmaceuticals such as salves and creams. Neem oil is used in cosmetics for creams, lotions and shampoos.

It has a wide spectrum of action and can be safely used for a variety of skin conditions. Neem oil and many of its constituents have been successfully used against a wide range of bacteria, viruses, fungi and parasites. Neem oil has been reported to be effective against certain human fungi, which are even difficult to control, by modern synthetic fungicides. These include some Trichophyton, Epidermophyton, Microsporum, Trichosporon, Geotricum and Candida. Neem oil inhibited the growth of all the three strains of Mycobacterium in a concentration of 12.5 mg/ml.

Neem oil has consistently shown moderate to potent anti-bacterial activity against a wide range of Gram positive and Gram negative microorganism. The oil possess marked spectrum of anti-bacterial activity against Gram negative and positive microorganisms including M. tuberculosis, streptomycin resistant strain. Neem oil absorbs quickly into the skin and has good skin penetration. It’s compounds are non-irritating and are known to have a minimum of allergic reactions. It is neither too hot (ushna) nor too cold (sheetha) in potency (veerya) and subsides pitta and kapha dosha, promoting holistic health for mind, body and spirit.

If you are looking for a natural remedy for skin irritations, pure medicinal grade Neem oil could well be your answer.


Apart from its suitability to provide shade and for Afforestation the wood of the neem tree is very much in demand. The trunk and branches are ideal for building being both strong and rather resistant to termites. It is also used for firewood and in the making of charcoal.

There is an important point to remember when using neem for firewood: If, as is common practice in many countries, the branches and the top of the tree are regularly pruned, it will be some time before the trees again produce fruit as they will first try to re-establish branches. Thus the combined use of the neem tree for insecticide and firewood is only possible when the tree is left undisturbed for several years. In other words: In order to produce insecticide, the original branches should be left intact (fruit production begins in 3 – 4 years). Only trees that are at least 10 years old should be used for firewood and only after the younger trees, planted later, have begun to produce sufficient fruit.


The neem tree (Azadirachta indica A. Juss) thrives almost anywhere in the tropical lowland, upto 800 m above sea level. It is resistant to extreme drought and grows where the annual rainfall is as sparse as 300 mm. Moreover, it grows very quickly and makes few demands on the soil fertility. The neem tree, therefore, grows in a wide variety of places. Hilltops and infertile, depleted land (e.g., Eroded hillsides) are as suitable as stony, flat land or hard laterite. The neem tree may be used to line avenues, to border roads or fields and in mixed cultivation with fruit trees. The average annual fruit yield from a mature neem tree is above 20 kg. Apart from insecticides, neem oil may be extracted from the seed. 30 kg neem seeds produce 6 – 8 kg oil. The resulting residue can be used to make insecticides in a similar way as from the whole neem seeds described earlier.

All parts of the neem tree can be utilized. Insecticidal substances are present in various parts of the tree; the highest concentrations are, however, contained in the seeds.

Azadirachtin, the most important insecticidal substance contained the plant, has, even in very small doses, a growth disrupting effect on many insect larvae, i.e. insects which eat this substance are unable to develop to the next larval / nymphal stage and die off. Other pests, such as grasshoppers, avoid or reduce feeding as a reaction to azadirachtin. As tests have repeatedly confirmed, due to its special mode of action, the neem extract is quite harmless for useful insects. Unlike synthetic pesticides, tests carried out over a longer period indicate that development of any resistance to the neem extract is in the short term unprobable. However, where intensive vegetable cultivation is practiced, the exclusive use of neem extract is inadvisable.

One great advantage of the neem extract is that even after repeated application on vegetable crops, it remains perfectly harmless for humans.


  1. Pest tolerance in crop land is usually based on the cost of control. Sometimes pests can be numerous and do considerable damage to a crop before the cost of that damage outweighs the cost of control.
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