Neem

Azadirachta indica

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:

• Neem extract can protect your crops against moths, aphids, leaf and plant hoppers, leaf miners, grasshoppers, scale insects, whiteflies and nematodes.
• Spray neem all over the leaves, but  especially the undersides where insects like to hide. If you have any left over, drench the soil around the roots as well.
• Do not spray in full sun as neem may cause leaf burn. Also, apply in the evening to avoid the azadiractin being destroyed by sunlight.
• Spray at least once every 2 weeks.
• Wait at least 3 days after spraying before harvesting the crop.

Method 1 - FRESH LEAVES

• Collect 1 kg of green leaves in a strong bowl or bucket (Photo 5)
• Add 5 litres of water
• Soak the leaves overnight (12 hours) OR pound the leaves with a heavy stick- like a baseball bat and soak overnight (Photo 6).
• If not pounded, remove the leaves to another bowl or bucket, and keep the water; pound the leaves, and squeeze out the liquid. Combine the two liquids.
• If already pounded, collect leaves and squeeze out the liquid (Photo 7)
• For both lots, strain the liquid through a kitchen sieve or muslin cloth to remove leaf pieces.
• Add about 20 g soap into a small amount of water until dissolved.

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

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, or inhale the dust when preparing dried leaves or seed. 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 (Fact Sheet no. 056) and the Pesticide label - how to read it? (Fact Sheet no. 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.