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February 2009. A question about how to use need provoked a lot of discussion.
Mosquitoes
Members said that having the tree near the house had the effect of repelling mosquitoes. It seems that taking cuttings and putting them inside the house also had the effect of repelling them. Perhaps the volatile compounds in the leaves have a repellent effect.
Target pests
Neem oil is said to control: aphids, beetles, grasshoppers, leafhoppers, scale insects, thrips, weevils and whitefflies. See desertwaterwisegardens.suite101.com/article.cfm/neem_oil.
Neem preparations
Methods of preparing neem from leaves and also seed is given at www.oisat.org/control_methods/plants_in_pest_control/neem.html. The method of preparing neem oil is given at the website mentioned under Target pests.
Take the ground seed and soak it in water for a night, strain and apply. This is called NSKE (Neem Seed Kernel Extract). Prepare NSKE by soaking 50 gm of neem seed kernel powder in one litre of water for 24 hours. Next day filter it using two-layers of cloth and add 1 ml of washing-up liquid. Spray the solution on the plants, preferably in the evening.
Uses
Neem works as an anti-feedant and repellent against leaf eating and sucking insects. It should be used immediately as the effectiveness reduces very quickly. Seed can be stored for some time, but old seed is less effective. It also has anti-bacterial, anti-fungal and ovicidal properties.
Neem is used in cleaning skin and wounds; and the kernel oil is also used in soaps. Extracts are variously used in the preparation of toiletries and soaps; neem twigs are used as tooth-brushes; very young leaves are fried with potato and eaten to prevent infectious diseases (Bengal). Neem is also used in veterinary medicine. In India, people believe that neem will cure chicken pox by keeping the leaf in the house during summer. Even when people become infected, neem is placed with that person in an isolated room.
Commercial preparations
Azadarachtin can be purchased, but it is expensive, has generally less effect, is not really stable at high temperatures and its shelf life is not long. See www.neem-products.com/seed-extract.html
The following website provides some info: http://www.neem-products.com/seed-extract.html.
Invasiveness
Neem is a highly invasive tree. See www.discoverneem.com/neem-weed.html. It certainly is not the first noxious weed to threaten the remote Kimberley region in Western Australia, but it is one of the most invasive and fastest spreading.
…the authorities realised that the devastating impact of the invasive weed far outweighed the possible economic benefits of the “wonder herb”…
“There is a need for immediate policy measures and actions to remove the risk of further infestations developing, to document the scale of current infestations, and put in place strategies for containment or, where possible, eradication.”
The Kimberley is only one example, the same thing is happening all over tropical Australia. Neem is naturalised around Darwin and Katherine, it’s thick in the Victoria River region, and it has spread through Queensland.
In summary, neem has high seed output, freely suckers from roots and stumps, and, with its insecticidal properties, few or no locally occurring herbivores (natural enemies) will keep it under control.
General information
www.gigers.com/matthias/engmala/neemtree.htm
www.discoverneem.com/neem-tree-as-insect-repellent.html
NSKE is excellent for Diamond back moth control, and also for Spodoptera and Helicoverpa, if sprayed at the 1st instar stage. The crushed kernel (after the preparation of NSKE) can be turned into the soil during land preparation as an organic manure. It seems to have an impact on root-knot nematode infestations. However, a member from Zambia reported that the result was often inconsistent against Diamond back moth. The best results are obtained from an emulsified extract, i.e., a commerical product.
Neem should not be confused with the Chinaberry Tree, Melia azedarach. Chinaberry does not have the same properties as neem, and it is also poisonous to humans and other animals. See PIER website, www.hear.org/pier.
In Cambodia, the leaves are eaten, after dipping in hot water; they have also been used against ticks on pigs, and grain weevils by placing dried leaves between the bags.
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