The Kohomba tree [Azadirachta indica] is indigenous to Sri Lanka and the dry forest areas of South East Asia including India, Pakistan, Thailand Malaysia and Indonesia. However, the tree is now grown in many parts of the world, even as far as Southern Florida and Arizona in the United States. It grows almost anywhere in the lowland tropics up to an altitude of about 1500 meters. It can withstand severe droughts and has a strong root system that can extract nutrients and moisture from poor soils. The taproot of this tree is nearly twice the height of the tree and a tree can grow up to 20 meters and a girth of 2.5 meters. It is believed that Kohomba leaves being slightly alkaline are good to neutralize acidity in the soil.

The Kohomba tree has been held in high esteem because of its medicinal and insecticide properties and it is a tree our ancestors planted near their houses. It has been an indispensable part of our home remedies for ages. Listed below are some common uses of Kohomba.

* Chewing 8 – 10 leaves early in the morning for twenty-four days protects the body from diseases like diabetes and hypertension. The body is also said to become immune to skin problems by this medication.

* A mixture of powdered seeds, rock salt and alum in equal quantities by weight is effective as a tooth powder.

* A decoction prepared from the leaves is used as a head wash to prevent premature graying, hair loss and to remove lice and dandruff.

* Four seeds powdered and mixed with warm water and taken as a drink on an empty stomach for a week is said to stop bleeding piles.

* From time immemorial Kohomba twigs have been used as a toothbrush. One end of the twig is chewed so that the fibers of the twig can be used as a brush.

* The aromatic oil obtained from the seed is much valued in Ayurvedic medicinal preparations.

Propagation

There is no dormant period for Kohomba seeds and they can be sown soon after harvesting. In fact there is a belief that their viability decreases with age. Seeds should first be immersed in water and only those that sink to the bottom are suitable for germination. Seeds can be sown directly or transplanted after growing them in polythene bags. A good soil mixture is, farmyard manure, sand and soil in the ratio 1:1:3. Seeds should be planted at a depth of 1 – 1.5 cm and watered. Two or three seeds can be sown in each bag, and they will germinate in about a week’s time. The healthy seedling is retained and the others removed after they are about two weeks old. The seedlings are ready for planting in the field in 4 – 6 weeks time when they are 15 – 25 cm in height but with the tap - root still inside the bag.

The late Chris de Saram and I often discussed the feasibility of sowing Kohomba seeds in the dry zone at the beginning of the monsoon rains, from a helicopter. The better alternative may have been to adopt " One Straw Revolution", Masanobu Fukuoka’s method of making half inch red-clay balls containing a mixture of seeds including Kohomba, microbes and humus, all rolled inside a protective clay coating. The clay shells defend the seeds from drought, insects, rodents and birds that would otherwise eat them before they sprout. These seed balls can be sown at any time of the year. When the monsoon rains commence and sufficient rains have fallen the protective clay will dissolve and the seeds inside will germinate and grow, with the microbes and humus in the pellet giving them a good start.

Harvesting of Seeds

After identifying trees that have yellow fruit, a mat or plastic sheet is spread under the tree and the branches are beaten with a stick. Seeds thus collected are brought to the shade where the pulp is removed by twisting the yellow fruits between the index finger and thumb. When the pulp is removed the seeds will be white in colour. The seeds are dried in the shade for two or three days before storage.

Kohomba Products and their Uses

In recent times, Kohomba has been attracting worldwide attention mainly due to its bioactive ingredients that are finding increasing demand in modern crop and grain protection. Research has shown that Kohomba extracts can influence a wide range of insects, even those that are resistant to chemical pesticides. Kohomba extracts will not kill pests instantaneously but will incapacitate them in several other ways.

Kohomba Kernel Extract

The outer seed cover should be removed and only the kernel should be used. If the seeds are fresh 3 Kgs are adequate for an acre but if the seeds are old, 5 Kgs are required. The kernel should be pound gently and placed in an earthen pot. To this 10 litres of water should be added and the mouth of the pot tied securely with a cloth and left for three days. After three days, on filtering 6 – 7 litres of the extract can be obtained. The shelf life of this extract is about one month. 500 – 1000 ml of this extract mixed with 9 litres of water can be sprayed. The addition of soap solution at 10 ml per litre of mixture will help the extract to stick well to the leaf and stem surfaces.

Kohomba Leaf Extract

10 – 12 Kgs of Kohomba leaves are required for use in an acre of land. Pound the leaves gently and place them in a pot. To this add 20 – 24 litres of water, tie the mouth of the pot securely with a cloth and leave it for three days. On filtration after three days 15 – 17 litres of the extract can be obtained. The shelf life of this extract too is about one month. 500 – 1000 litres of the extract diluted in 9 litres of water can be sprayed. Here again, the addition of soap solution at 10 ml per litre of mixture will help the extract to stick well to the leaf and stem surfaces.

Note: Since large quantities of leaves are required for preparing this extract, it is preferable to use this extract for nurseries and home gardens. The concentration of both these extracts can be increased or decreased depending on the intensity of the pest attack.

To prepare the soap solution, ordinary bar soap soaked in water over night can be used. The soap solution should be sticky and thick in nature.

Kohomba Cake Extract

10 Kgs of Kohomba cake is required for an acre of land. Powder the Kohomba cake well and place it in a cotton cloth and tie it in a pouch. Place this bundle in a vessel containing 20 litres of water for three days. Squeeze the pouch well into the water. About 15 to 17 litres of extract can be obtained. 500 – 1000 ml of extract should be diluted in 9 litres of water for spraying. The addition of 10 ml soap solution per litre of mixture is recommended for better adhesion.

* Spraying should be undertaken in the morning or late in the evening.

* As insects lay eggs on the undersides of leaves it is necessary to spray under the leaf as well.

* It is better to start with lower concentrations of extracts and then increase the concentration, if required.

Kohomba as a Prophylactic

1. Take Kohomba leaves, kernel or cake. Pound well and place in a pot. Add twice the volume of water and tie the mouth of the pot with a cloth and leave it for three days. Place four of these pots in the four corners of a field. In the evening open the mouths of the pots by removing the cloth cover. The foul smell emanating from the Kohomba products, prevent entry of pests into the field.

2. Place gunny bags filled with Kohomba cake along water canals. The Kohomba cake dissolves in the water and it irrigates the fields. This practice prevents the attack of pests and diseases that affects the roots and tillers of the crop.

Kohomba for Stored Grain

Grains and pulses can be stored after mixing with Kohomba products like dried leaf powder, kernel powder or oil. Stored grain is also fumigated with the smoke of Kohomba leaves. When oil is used against stored grain pests, it should be at the rate of 1 percent by weight of the grain. The active ingredients of the Kohomba tree like Azadirachtin, Salanin and Malandriol are concentrated in the seed. Therefore the use of seed, oil or kernel extract is always recommended.

Kohomba, has the potential to control many pests and diseases. It has been used traditionally in the East for a variety of purposes and continues to be used even today earning the name, "the tree of a hundred uses". One of the main advantages of this tree is that it is easy to propagate and once it has been established it needs very little attention or care. It is a perennial that can be regularly harvested for decades.

With the growing concern all over the world about the environmental harm caused by chemical pesticides, research scientists should as a matter of urgency, look for alternative methods of pest control. There is already a big demand for pesticides from plants rather than from petroleum products and Kohomba has the ability to meet this growing demand.