[<< wikibooks] Horticulture/Neem Oil
Neem oil is a vegetable oil pressed from the fruits and seeds of the Neem tree, Azadirachta indica, which is endemic to the Indian sub-continent and has been introduced to many other areas in the tropics. It is perhaps the most important of the commercially available products of neem.
The oil is generally light to dark brown, bitter and has a rather strong odour that is said to combine the odours of peanut and garlic. It comprises mainly triglycerides and large amounts of triterpenoid compounds, which are responsible for the bitter taste. It is hydrophobic in nature and in order to emulisify it in water for application purposes, it must be formulated with appropriate surfactants.
Neem oil also contains steroids (campesterol, beta-sitosterol, stigmasterol) and a plethora of triterpenoids of which Azadirachtin is the most well known and studied. The Azadirachtin content of Neem Oil varies from 300ppm to over 2000ppm depending on the quality of the neem seeds crushed. 

The method of processing is likely to affect the composition of the oil, since the methods used,
such as pressing (expelling) or solvent extraction are unlikely to remove exactly the same
mix of components in the same proportions.The Neem oil yield that can be obtained from neem seed kernels varies also widely in literature and varies from 25% to 45%.
The oil can be obtained through pressing (crushing) of the seed kernel both through cold pressing or through a process incorporating temperature controls. 
Neem seed oil can also be obtained by solvent extraction of the neem seed, fruit, oilcake or kernel. A large industry in India extracts the oil remaining in the seed cake using hexane. This solvent-extracted oil is of a lower quality as compared to the cold pressed oil and is mostly used for soap manufacturing.
Neem cake is a by-product obtained in the solvent extraction process for neem oil.

== Uses ==
Neem oil is not used for cooking purposes but, in India and Bangladesh, it is used for preparing cosmetics (soap, hair products, body hygiene creams, hand creams) and in Ayurvedic, Unani and other traditional medicines is used in the treatment of a wide range of afflictions. The most frequently reported indications in ancient Ayurvedic writings are skin diseases, inflammations and fevers, and more recently rheumatic disorders, insect repellent and insecticidal effects.
Traditional Ayurvedic uses of neem include the treatment of fever, leprosy, malaria, ophthalmia and tuberculosis. Various folk remedies for neem include use as an anthelmintic, antifeedant, antiseptic, diuretic, emmenagogue, contraceptive, febrifuge, parasiticide, pediculocide and insecticide. It has been used in traditional medicine for the treatment of tetanus, urticaria, eczema, scrofula and erysipelas. Traditional routes of administration of neem extracts included oral, vaginal and topical use. Neem oil has an extensive history of human use in India and surrounding regions for a variety of therapeutic purposes.
Formulations made of Neem oil also find wide usage as a bio-pesticide for organic farming, as it repels a wide variety of pests including the mealy bug, beet armyworm, aphids, the cabbage worm, nematodes and the Japanese beetle. Neem Oil is non-toxic to mammals and birds as well as many beneficial insects such as honeybees and lady bugs. Neem oil also controls black spot, powdery mildew, anthracnose and rust.

== Action ==

== Application ==
Applied in a spray at 100:1 or 200:1. Agitation is recommended.

== Precautions ==

== Resistances ==

== References ==
Evaluation of Cold-Pressed Oil from the Seed Kernels of Azadirachta Indica (A.Juss), Meliaceae (Neem) for use in Listable Therapeutic Goods; Office of Complementary Medicines, Therapeutic Goods Administration (TGA), Australia
N. Kaushik and S. Vir. Variations in fatty acid composition of neem seeds collected from the Rajasthan state of India; Biochemical Society Transactions 2000 Volume 28, part 6
Schmutterer, H. (Editor) (2002) The Neem Tree: Source of Unique Natural Products for Integrated Pest Management, Medicine, Industry And Other Purposes (Hardcover),2nd Edition, Weinheim,Germany: VCH Verlagsgesellschaft .ISBN 3-527-30054-6
Vietmeyer, N. D. (Director) (1992), Neem: A Tree for Solving Global Problems. Report of an ad hoc panel of the Board on Science and Technology for International Development, National Research Council, Washington, DC, USA: National Academy Press. pp.71-72. ISBN 0-309-04686-6