Azadirachta indica, commonly known as neem, nimtree or Indian lilac, and in Nigeria called dogoyaro or dogonyaro, is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to the Indian subcontinent and most of the countries in Africa.
It is typically grown in tropical and semi-tropical regions. Neem trees also grow on islands in southern Iran. Its fruits and seeds are the source of neem oil. The extract comes from the seeds of the tree and has many different traditional uses. Neem is known for its pesticidal and insecticidal properties, but people also use it in hair and dental products.
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15–20 m tall (sometimes up to 40 m tall)
The tree is easily propagated both sexually and vegetatively. It can be planted using seeds, seedlings, saplings, root suckers, or tissue culture. However, it is normally grown from seed, either planted directly on the site or transplanted as seedlings from a nursery.
The seeds are fairly easy to prepare. The fruit drops from the trees by itself; the pulp, when wet, can be removed by rubbing against a coarse surface; and (after washing with water) the clean, white seeds are obtained. In certain nations—Togo and Senegal, for example—people leave the cleaning to the fruit bats and birds, who feed on the sweet pulp and then spit out the seeds under the trees.
It is reputed that neem seeds are not viable for long. It is generally considered that after 2-6 months in storage they will no longer germinate. However, some recent observations of seeds that had been stored in France indicated that seeds without endocarp had an acceptable germinative capacity (42 percent) after more than 5 years.
Growing a Neem Tree
Neem is a hardy tree that can tolerate temperatures up to 120 degrees F. (50 C.). However, extended cool weather with temperatures below 35 degrees F. (5 C.) will cause the tree to drop its leaves. The tree won’t tolerate colder temperatures, wet climates, or prolonged drought. That being said, if you can locate fresh neem tree seeds, you can grow a tree indoors in a pot filled with good quality, well-drained potting soil. Outdoors, plant fresh neem seeds directly in the ground, or start them in trays or pots and transplant them outdoors at about three months. If you have access to mature trees, you can root the cuttings in late fall or early winter.
Neem Tree Care
Young neem trees benefit from regular moisture and should be watered once every week. Neem trees don’t do well in poorly drained soil and don’t tolerate wet feet so be sure not to overwater them.
The soil should be allowed to dry between every watering session.
Be sure to feed the tree with good quality fertilizer, diluted fish emulsion, or a dilute solution of water-soluble fertilizer. Do this at least once every month in spring and summer.
Cut back your neem tree in spring followed by a smaller trimming towards the end of summer. A healthy neem tree responds well to being cut back by producing lots of new shoots.
If your aim is to harvest your neem leaves for home remedies, you can do so without worrying about the cut back. Just remember that your tree will need a lot of feeding to make up for those leaves.
When it comes to pests and diseases of neem trees, be on the lookout for scale insects. The oriental yellow scale (Aspidiotus orientalis) and the neem scale (Palvinaria maxima) can cause considerable damage to your tree.
By and large, most neem trees are reputed to be remarkably pest free; however, in Nigeria 14 insect species and 1 parasitic plant have been recorded as pests. Few of the attacks were serious, and the trees almost invariably recovered, although their growth and branching may have been affected.
However, in recent years a more serious threat has emerged. In some parts of Africa (mainly in the Lake Chad Basin), a scale insect (Aonidiella orientalis) has become a serious pest. This and other scale insects sometimes infest neem trees in central and south India. They feed on sap, and although they do little harm to mature trees, they may kill young ones. Now that one type has been detected in Africa, the impact could be severe.
Other insect pests include the following:
The scale insect Pinnaspis strachani (very common in Asia, Africa, and Latin America);
Leaf-cutting ants Acromyrmex spp. (common defoliators of young neem trees in Central and South America);
The tortricid moth Adoxophyes aurata (attacks leaves in Asia including Papua New Guinea);
The bug Helopeltis theivora (considered a serious neem pest in southern India); and
The pyralid moth Hypsipyla sp. (attacks neem shoots in Australia).
Even though neem timber is renowned for termite resistance, termites sometimes damage, or even kill, the living trees. They usually attack only sickly specimens, however.
Despite the fact that the leaves contain fungicidal and antibacterial ingredients, certain microbes may attack different parts of the tree, including the following:
Roots (root rot, Ganoderma lucidum, for instance);
Stems and twigs (the blight Corticium salmonicolor, for example);
Leaves (a leaf spot, Cercospora subsessilis; powdery mildew, Oidium sp., and the bacterial blight Pseudomonas azadirachtae)
Seedlings (several blights, rots, and wilts—including Sclerotium, Rhizoctonia, and Fusarium).
A canker disease that discolors the wood and seems to coincide with a sudden absorption of water after long droughts has also been observed.
A lack of zinc or potassium drastically reduces growth. Trees affected by zinc deficiency show chlorosis of the leaf tips and leaf margins, their shoots exude much resin, and their older leaves fall off. Those with potassium deficiency show leaf tip and marginal chlorosis and die back (necrosis).
Fire kills neem seedlings outright. However, mature trees almost always regrow, especially if the dead parts are quickly cut away.
High winds are a potential problem. Large trees frequently snap off during hurricanes, cyclones, or typhoons. Neem is therefore a poor candidate for planting in areas prone to such violent storms.
Seedlings regenerating beneath stands of neem are sensitive to sudden exposure to intense sunlight. Thus, clear-felling neem trees normally produces a massive seedling kill, especially if the seedlings are small.
In some localities rats and porcupines kill young trees by gnawing the bark around the base. Even when not causing any physical damage, rodents can be pests: wherever they are numerous, the fruits may disappear before the farmer can harvest them.
Neem, with its intensely bitter foliage, is not a preferred browse, but if nothing else is available goats and camels will eat it. In fact, in Asia goats and camels have been known to browse young neem trees so severely in times of scarcity that the plants died. In Africa neem is generally ignored by livestock (which makes the tree easy to establish even within villages and courtyards). The reason that livestock treat neem differently in Asia and Africa is unknown at present. It may be differences in the tree specimens, or in the animals' preferences or past experiences.
Neem oil is a common pest repellant, effective against sand fleas and mosquitoes. Other forms of neem can help control termites and repel moths.
Some manufacturers add neem to animal shampoos to repel ticks and fleas. They may also add it to cattle feed or grain to repel pests and parasites.
Neem is a strong antioxidant, neutralizing free radicals that may influence the development of some conditions. It is also a strong anti-inflammatory agent.
Neem has antimicrobial effects and may be effective against several types of bacteria, viruses, and fungi.
As neem is effective against mosquitoes, it may also have anti-malarial properties. Malaria is a parasite that some mosquitoes carry. It causes around 219 million illnesses and 435,000 deaths worldwide each year.
The bark, leaves, and seeds are used to make medicine. Less frequently, the root, flower, and fruit are also used.
Neem leaf is used for leprosy, eye disorders, bloody nose, intestinal worms, stomach upset, loss of appetite, skin ulcers, diseases of the heart and blood vessels (cardiovascular disease), fever, diabetes, gum disease (gingivitis), and liver problems. The leaf is also used for birth control and to cause abortions.
The bark is used for malaria, stomach and intestinal ulcers, skin diseases, pain, and fever.
The flower is used for reducing bile, controlling phlegm, and treating intestinal worms.
The fruit is used for hemorrhoids, intestinal worms, urinary tract disorders, bloody nose, phlegm, eye disorders, diabetes, wounds, and leprosy.
Neem twigs are used for cough, asthma, hemorrhoids, intestinal worms, low sperm levels, urinary disorders, and diabetes. People in the tropics sometimes chew neem twigs instead of using toothbrushes, but this can cause illness; neem twigs are often contaminated with fungi within 2 weeks of harvest and should be avoided.
The seed and seed oil are used for leprosy and intestinal worms. They are also used for birth control and to cause abortions.
The stem, root bark, and fruit are used as a tonic and astringent.
Some people apply neem directly to the skin to treat head lice, skin diseases, wounds, and skin ulcers; as a mosquito repellent; and as a skin softener.
Inside the vagina, neem is used for birth control.
Neem is also used as an insecticide.
Tree: the neem tree is of great importance for its anti-desertification properties and possibly as a good carbon dioxide sink. It is also used for maintaining soil fertility.
Fertilizer: neem extract is added to fertilizers (urea) as a nitrification inhibitor.
Animal feed: neem leaves can be occasionally used as forage for ruminants and rabbits.
Teeth cleaning: neem has traditionally been used as a type of teeth-cleaning twig.
Although experts generally consider neem safe for use, it is possible for someone to have an allergy or sensitivity to it.
Before using neem for the first time, consider doing a patch test. To do a patch test, rub a few drops of neem onto a patch of skin on the inner forearm.
Wait 24 hours, then look at the site to see whether a reaction has occurred. Any signs of discoloration, swelling, itching, or discomfort indicate that a person may be sensitive to the oil and should avoid using it again.