FGTC Species Highlight - Neem Tree (Azadarachtin indica)
By Mary Anne Wambui, Waruhiu County Trainer, Kenya
Azadiractha indica, commonly known as the Neem tree, is a small to medium- sized tree in the mahogany family Meliacaea, and is one of the two species in the genus Azadirachta. It is usually evergreen and grows up to 30 meters tall, with a round, large crown up to 10 meters in diameter. It has grey-brown rough bark and compound leaves, with 5-8 pairs of leaflets which are toothed along the edge. Neem has gained a lot of popularity throughout the tropics and subtropics due to its highly valued hardiness, almost year-round shade, and its multiple wood and non-wood products. It grows best in hot lowland areas, flourishing in very dry places.
English: Neem, margosa Indian lilac, neem tree, Indian cedar
French: Neem, nim, margousier
Swahili: Muarubaini, mkilifi
Spanish: Lila india
Where it Grows
Neem is native to the Indian subcontinent and southeast Asia. It later spread to North Australia, tropical Asia, Africa, Mauritius, Puerto Rico, the Caribbean, and many countries in south and central America.
Rainfall: Mean annual rainfall 400-1,200 meters. Does not tolerate water logging.
Temperature: Can withstand temperatures up to 50C with mean annual temperature of 21-32C. Does not tolerate temperatures below 5C.
Sunlight: Does well in plenty of bright sunlight.
Altitude: 0-1,500 meters above sea level.
Soil: Grows in a wide range of neutral to alkaline soils but performs better than most species on shallow, stony, sandy soils or in places where there is a hard calcareous or clay pan. It does best in pH ranging from 6.2-7 (slightly acidic) but can still tolerate a pH of up to 8.5.
Controls soil erosion
Living Fence and Windbreak – Neem is low branching hence able to serve as a windbreak
Apiculture – Produces clusters of small white flowers that attract bees.
Compost and Organic Manure – The leaves are used as mulch or green manure. Neem cake is used for soil amendment as it prevents mildew and rust.
Intercropping – Neem has effectively been intercropped with pearl millet and Pennisetum glaucum.
Integrated Pest Management – Azadirachtin (main compound found in neem) serves as a repellent to many pests.
Shade or Shelter – The large crown makes it an effective shade tree.
Food: Fruits can be eaten fresh, cooked, or prepared as a dessert. The young twigs and flowers are occasionally consumed as vegetables.
Fodder: The leaves are often used as dry season fodder.
Fuel: Wood is used as firewood and for charcoal production.
Timber: Produces posts for construction and fencing. It has insect repellant qualities against termites, borers, and fungi which increases the quality of its wood.
Gum or Resin: Used as a food additive because of its high protein material. It is also used as neem-glue in Southeast Asia.
Tannin and Dye: Contains 12 -14 % tannins
Neem Oil: Used in the production of soaps, cosmetics, pharmaceuticals and other non-edible products.
Organic Pesticide: Contains azadirachtin which makes it useful in insect control as it distorts their reproduction cycles. It is also used to make Neem tea, which is a pesticide made from dried, crushed seeds that are soaked overnight. The leaves repel insects and are used to preserve grains.
Medicine: Neem has proven effective against certain fungi and several species of pathogenic bacteria that infect humans. It is said to treat 40 diseases which is where its Swahili name comes from: “Muarubaini.”
Neem produces cream-white flowers, which hang in clusters. The fruit is a smooth oval shape, initially green and turning yellow when ripe, with seeds 1.2-2.0 centimeters long. Neem seeds are recalcitrant seeds and not ideal for storage. They will not survive if left in a dry place at room temperature for an extended period. They have a short viability of about 3-4 weeks. Drying the seeds slowly and keeping them at a low temperature of 4C can allow for storage up to 7-8 months (ECHO 1996). There are about 4000 – 4500 seeds/kg.
Neem is a tropical to subtropical tree that can tolerate varying water quality and thrives in the merest trickle of water. Weeding is essential since the tree cannot withstand competition, especially from grass. Neem trees respond well to coppicing and pollarding, but seed production is adversely affected when lopped for fodder. It can survive for 100 to 200 years.
Neem is mainly propagated by seed but can be propagated through cuttings. They can be sown in tree sacks or as bareroot. Fresh Neem seeds germinate within one to three weeks and are transplanted in about three months. Fresh seeds can be directly sown under existing vegetation. No seed pretreatment is required. Seeds are often dispersed by birds, bats, and baboons that eat the sweet yellow fruit around the seed kernels.
Pest and Diseases
Neem has few serious pests, but several scale insects have been reported to infest it: such as Pulvinaria maxima. Rats and porcupines attack and occasionally kill the Neem tree seedlings by gnawing the bark around the base. In India, a common fungi Pseudocercospora subsesessils causes shot hole effect and bacterium Pseudomonas azadirachtae may damage the leaves.