Worldwide. South and Southeast Asia, Africa, South and Central America, the Caribbean, Oceania. It is recorded from Australia, Fiji, Solomon Islands, and other Pacific island countries.
Neem is a tree of the mahogany family (Photo 1). It is fast-growing, up to 20 m, evergreen, but may lose leaves in drought. Leaves up to 40 cm long with a flexible central midrib, bearing 20-30 paired leaflets, each one 3-8 cm long and attached to the midrib by a short stalk (Photo 2). Flowers are in clusters (Photo 3). The fruits are green, yellow when ripe, almost oval, olive-shaped, up to 3 cm long and 1.5 cm wide (Photo 4).
Neem is used in many ways: it improves soil fertility, so it is used in reclamation projects; it is made into plywood because it is resistant to termites, borers and decay by fungi; and it is used to treat scabies and lice affecting humans, and fleas on cats and dogs. It is also used as a vegetable, and in traditional medicines to cure many ailments.
Extracts from leaves and seeds are used as a pesticide (Photos 5-7). The most active chemical in them - azadirachtin - repels and kills insects and nematodes.
As a pesticide against some insects and nematodes:
Method 1 - FRESH LEAVES
Note, you can use the liquid from the leaves for up to 1week after preparation; but it is best to store in a cool, dark place.
Method 2 - DRIED LEAVES
Method 3 - SEEDS
See the cartoon video from the University of Illinois (https://www.youtube.com/watch?v=6U4FMgFdVAM)
If using a knapsack sprayer, keep the nozzle about 50 cm about the crop and spray over 250 m2 Keep the sieve and muslin used only for making neem spray. Do not use for food.
Note, you can use the leaves and seeds after pounding. Spread them around the crop to repel insects and also as a manure.
Neem is generally considered to be of low toxicity to humans, but that does not mean people should drink large amounts, allow it to contact skin or eyes; and do not inhale the dust. It should be treated like all pesticides: when working with neem take care. Wear protective clothing when you are preparing and applying it. The kinds of protective clothing to use are outlined in Preparing natural pesticides (056) and the Pesticide label - how to read it? (288).
In some parts of the world neem is invasive. In the Northern Territory of Australia, it invades waterways and has been declared a weed. However, because of its drought resistance (it can grow in regions with less than 400 mm rain) it is used as a shade tree in urban and rural areas.
AUTHOR Grahame Jackson & Kazuko Ota
Information from Azadirachta indicata (Neem) Bio-NET-EAFRINET. (https://keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Azadirachta_indica_(Neem).htm); and from Azadirachta indica Wikipedia. (https://en.wikipedia.org/wiki/Azadirachta_indica). Photo 3 JM Garg Azadirachta indica in Hyderabad, India.
Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.
This fact sheet is a part of the app Pacific Pests and Pathogens
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