How farmers in Uganda can grow star fruit for its medicinal benefit

The carambola, commonly known as star fruit, is a geometrically stunning, tender sweet fruit that comes from the averrhoa carambola plant.
The tree is native to the Asian continent; however it is also grown in tropical areas including Uganda and it is commonly known in the Luganda language as muzadibu.

Its fruit has a distinctive ridge running down its sides and those who know about it use it for blending juice.
It is mainly grown in villages in central Uganda for home consumption but experts think it can be grown on large scale due to its nutritional and medicinal value.

Background
Malaysia is a global leader in star fruit production by volume and ships the product widely to Asia and Europe.
The star fruit producing plant is a species of woody plant in the family Oxalidaceae native to the Philippines, Indonesia, Malaysia, Vietnam, India, Bangladesh and Sri Lanka but, cultivated in many parts of the world.

It is a popular tropical fruits and used commonly in traditional Chinese medicines including to relieve ailments such as chronic headache, fever, cough, gastro-enteritis, diarrhoea, ringworm infections and skin inflammations. 
It contains five species, namely A. bilimbi, A. dolichocarpa, A. leucopetala, A. microphylla and A. carambola, where A. carambola is widely cultivated on a commercial scale.
The common ones grown by Ugandans in their homesteads are the sweet type which include the large fruit type Bell, Arkin, Maha and Dmak and the sour type which have smaller fruits are Star King, and Newcomb. 

Health benefits
The experts contend that phytochemical and pharmacological studies suggest that the extracts of Star fruit plant leaves, fruits and roots contains saponins, flavonoids, alkaloids and tannins which are known to confer antioxidant and specific healing properties .
The major vitamins and acids found in star-fruits can therefore be useful in treating fever, sore throat, cough, asthma, chronic headache and skin inflammations.

How to propagate star fruit
The star fruit propagation is similar to most woody tropical plants, in that they can be effectively propagated by seeds, cloned or by cuttings. However cutting and air layering is the most ideal approach.
The seeds don’t usually remain viable long enough to grow the trees from seed, so it is best to reach out to a nursery to obtain seedlings.
It is also possible to graft star fruit branches onto other fruit trees with a similar growth cycle and climate needs.

Soil requirement 
The fruit tree thrives in several types of soil but does best in well drained, loamy soils rich in organic matter.
Planting can be done by using seed where holes are made and one seed is dropped in the hole and covered with soil. 
Alternatively a farmer may place the seeds in a moist paper towel in a plastic bag and place them in a warm dark place. In optimal conditions seeds may germinate in a week.

For cuttings, get an existing star fruit tree, cut off branches which have buds. Ensure to cut the stems are at an angle, place them in a rooting hormone and then into well prepared polythene packs with potting soil.
Ensure to water the cuttings and after two or three weeks the roots will get established.

Alternatively the farmer can air layer the branches of trees and this involves thinly debarking 3-4 cm of the lateral branches to expose the inner layer.
Then clean the scraped area and smear a rooting hormone on to the exposed part, place a ball of moist soil and wrap in a transparent polythene sheet.
Secure tightly with a string at both ends of the wrap. After several weeks the roots will form underneath the soil ball. Cut off the rooted branch from the mother tree at four centimetres below the wrap, then transplant in to polythene bag for further hardening and growth.
Care
The trees need plenty of bright sunlight to flourish at least seven hours of direct sun per day. If growing in a container, make sure it has a sunny window and the tree is turned occasionally to give it full exposure on all sides.

Watering
Water your star fruit tree regularly. Star fruit trees are not tolerant of drought. However, heavy consistent rain or overwatering may inhibit fruit production.
Pruning
Prune the tree lightly to keep it looking neat and encourage the balanced placement of fruiting branches. If the branches bend under the weight of the fruit, this is a sign that it needs pruning.

Common pests 
Star fruit trees are somewhat susceptible to various pests, including carambola fruit flies, ants and some birds who enjoy snacking on the fruit.
They may also be attractive to weevils such as stink bugs, squash bugs and thrips.
They are also prone, like other fruit trees, to some of the diseases such as fungal leaf spot, algal rust, anthracnose fruit rot, and pythium root rot.
These can be managed by applying recommended chemicals which can be sprayed ones the diseases are spotted.

Harvesting
After three years of planting carambola blooms for the first time and flowers take about two months to become fruits.
It is a green yellow fruit about 12 cm long and usually has 5 longitudinal ribs.
A ripe star fruit can be recognised by its yellow to orange flesh. It’s juicy and sweet with a high content of oxalic acid, its rich in vitamin A and C.
Farmers can start plucking the fruits once it turns yellow and looking mature. Avoid plucking them when they are still green and immature because they will be sour and not palatable to consume the juice.

Requirements 
Soil
Starfruit grows in a variety of soil types but soil that is well-drained, loamy, and rich in organic matter is suitable.
Watering
The plant should be regularly watered when it is young. Once established, water only when the soil is dry.

Fertilising
Fertilise young starfruit with 10-10-10 fertiliser every month, except in winter. Mature trees should be fertilised at the beginning of the growing season. Additionally, you can apply compost or manure to improve the soil texture.