Tamarillo, best known by the name tree tomatoes in Kenya is a fast-growing tree that grows up to 5 meters. Peak production is reached after 3-4 years of growing, and the crop is able to remain in production for about 12 years. The tree usually forms a single upright trunk with lateral branches. They produce 1 to 6 fruits per cluster. Plants can set fruit without cross-pollination, but the flowers are fragrant and attract insects commonly. Cross-pollination seems to improve fruit set.
Small tree that is attractive, half-woody, fast-growing, brittle and shallow-rooted reaching 10 to 18 ft (3-5.5 m) in height; rarely as much as 25 ft (7.5 m). The leaves are muskily odorous, evergreen, alternate and more or less heart-shaped at the base, broad, thin, and softly hairy, with conspicuous coarse veins.
Borne in small, loose clusters near the branch tips, the fragrant flowers, 1/2 to 3/4 in (1.25-2 cm) wide, have 5 pale-pink or lavender, pointed lobes, 5 prominent yellow stamens, and green-purple calyx. The long-stalked, pendent fruit, borne singly, or in clusters of 3 to 12, is smooth, egg-shaped but pointed at both ends and capped with the persistent conical calyx.
In size it ranges from 2 to 4 in (5-10 cm) long and l 1/2 to 2 in (4-5 cm) in width. Skin color may be solid deep-purple, blood-red, orange or yellow, or red-and-yellow, and may have faint dark, longitudinal stripes.
Flesh color varies accordingly from orange-red or orange to yellow or cream-yellow. While the skin is somewhat tough and unpleasant in flavor, the outer layer of flesh is slightly firm, succulent and bland, and the pulp surrounding the seeds in the two lengthwise compartments is soft, juicy, mildly acidic to sweet; it is black in dark-purple and red fruits, yellow in yellow and orange fruits.
The seeds are thin, nearly flat, circular, larger and harder than those of the true tomato and distinctly bitter. The fruit has a slightly resinous aroma and the flavor suggests a mild or under ripe tomato with a faintly resinous aftertaste.
Origin and Distribution
Although its place of origin is not certain, the tree tomato is generally believed to be native to the Andes of Peru and probably also Chile, Ecuador and Bolivia where it is extensively grown, as it is also in Argentina, Brazil and Colombia.
It is cultivated and naturalized in Venezuela and grown in the highlands of Costa Rica, Guatemala, Jamaica, Puerto Rico and Haiti. It must have been carried at an early date to East Africa, Asia and the East Indies, as it is well established in the Nilgiri heights and the hills of Assam in southern India, and in the mountains of Malaya, and was popular in Ceylon and the Dutch East Indies before 1903. It has been grown in Queensland, Australia, in home gardens, for many years and is a practical crop in the highlands of the Australian part of New Guinea.
Shortages of tropical fruits in World War II justified an increased level of production. A promotional campaign was launched in 1961; window banners and 100,000 recipe leaflets were distributed.
Varieties: The main varieties grown in Kenya are the:
Gold-mine, Inca red, Rothamer, Solid gold and Ruby red.
Some exotic cultivars are:
Fruit is medium orange in color, the size of a large hen’s egg. Are Pulp light orange, creamy in texture, less acid than the Ruby Red. Excellent for eating out of hand and also suited for culinary purposes.
Are very large golden-yellow fruit with golden, highly flavored flesh, less bland than Solid Gold, but not acidic. Have superb earring qualities.
A yellow-fruited cultivar said to be less acid than the red types. When cooked the fruit is said to resemble the apricot in flavor.
It is a large fruited red cultivar, oval to round in shape, with a sharp acid flavor. Good quality for eating out of hand and excellent for jams and preserves.
It’s a large fruit, over 3 ounces. Skin is bright red. Flesh golden-yellow, flavor sweet and exotic. Seeds are dark red. Ripen from December to April.
f.Ruby Red variety
It’s a large, brilliant red fruit. Its Pulp dark red, tart and flavorful
g.Solid Gold variety
It’s a large, oval shaped fruit. Skin is golden-orange in color, soft, less acidic in flavor than Oratia Red.
Fruit is the size and shape of a large plum. Skin is yellowish orange. Flesh yellow, with a milder flavor than the red types. The yellow form is the oldest in cultivation in New Zealand.
The tamarillos prefer subtropical climate, they grow in many parts of Kenya with rainfall between 600 and 4000 millimeters and annual temperatures between 15 and 20 °C. It is intolerant to frost (below -2 °C) and drought stress. It is assumed that fruit set is affected by night temperatures. Areas where citrus are cultivated provide good conditions for tamarillos.
Tamarillo plants grow best in light, deep, fertile soils, although they are not very demanding. However, soils must be permeable since the plants are not tolerant to water-logging. They grow naturally on soils with a pH of 5-8.5. They are as well planted by irrigation as they also do well.
Most farmers in Kenya use seeds as a means of Propagation but prpagationof this crop is also possible by the use of cuttings. The farmer should be aware that Seedlings first develop a straight, about 1.5 to 1.8 meters tall trunk, before they branch out. Propagation by seeds is easy and ideal in protected environments. Seedlings should be kept in the nursery until they reach a height of 1 to 1.5 meters, as they are very frost-sensitive.
Figure 2 TREE TOMATO SEEDS
Plants grown from cuttings branch out earlier and result in more shrub-like plants that are more suitable for exposed sites. Cuttings should be made from basal and aerial shoot, and should be free of pathogenic viruses. Plants grown from cuttings should be kept in the nursery until they reach a height of 0.5 to 1 meter. The easiest way to grow tree tomatoes as a crop is through seedlings. The tree grows very quickly and is able to bear fruits after 1.5 to 2 years though in some favorable conditions they carry fruits in a lesser span of time. The plant is day length-insensitive. The fruits do not mature simultaneously, unless the tree has been pruned.
A single tree can produce more than 30 kg fruits per year, an orchard yields in 15 to 17 tons per hectare. One single mature tree in good soil will bear more fruit than a normal family can eat in about 3 months.
- The tomatoes are planted at 4 feet and 5 feet as between the plants and within the row spacing respectfully.
- Dig 2.5ft by 2.5ft Mix one and a half wheelbarrow-row of well-prepared compost (chickens and pig manure are preferred) with two spade full of topsoil to plant the seedlings.
- Leave a shallow depression in every plant for placing the mulching material – only 1 feet of the tree tomato seedling should be buried while planting just enough to cover the root hairs. Selection of planting site is very important.
- Because of the shallow root system, deep cultivation is not possible, but light cultivation is desirable to eliminate weeds until there is sufficient vegetative growth to shade them out.
When the tree is about 1 to 1.5 meters in height, it is advisable to cut the roots on one side and lean the tree to the other (in the direction of the midday sun at about 30 to 45 degrees). This allows fruiting branches to grow all along the trunk rather than just at the top. An acre can be planted 1200 tree seedlings.
When planting tree tomatoes, approximately 200 grams of di-ammonium sulfate fertilizer should be applied in each and every plant. After two months of planting each and every plant should be supplied with Ammonium nitrate or urea (the white fertilizer) in 250 grams per plant in a span of 4 months for 4 years. .
The tree tomato cannot tolerate prolonged drought and must have an ample water supply during extremely dry periods. Mulch is very beneficial in conserving moisture at such times.
Tree tomato flowers are normally self-pollinating. If wind is strong enough to disrupt pollination, unpalliated flowers will drop prematurely.
Tamarillos are ready to harvest when they develop the yellow or red color characteristic of the particular variety. To harvest, simply pull the fruit from the tree with a snapping motion, leaving the stem attached.
The fruit can be stored in the refrigerator for up to 10 weeks, but temperatures below 38° F can cause the skin to discolor.
Figure 4 harvested fruits
PEST & DISEASES CONTROL
Tree tomato is fairly resistant to most diseases and pests. However, the tree is prone to powdery mildew, which causes the leaves to fall off. Application of copper oxychloride (allowed in organic farming) can control the disease. Neem extracts can also be used to control the disease. The main pests that attack the tree include the aphids, thrips whiteflies and nematodes. Pests can be prevented by continuous application of plant extracts (chilies, African marigold, garlic, neem) at least three times. The farmer should also observe a good crop rotational programme.
- Ripe tree tomatoes may be merely cut in half lengthwise, sprinkled with sugar and served for eating by scooping out the flesh and pulp. Or the halves may be seasoned and grilled or baked for 15 minutes for service as a vegetable.
- The fruit should not be cut on a wooden or other permeable surface, as the juice will make an indelible stain.
- For other purposes, the skin must be removed and this is easily done by pouring boiling water over the fruit and letting it stand for 4 minutes, then peeling is begun at the stem end.
- The peeled fruit can then be sliced and the slices added to stew or soups, or served with a sprinkling of sugar and perhaps with a scoop of vanilla ice cream.
- Seasoned with salt and pepper, the slices can serve as sandwich-filling or may be used in salads. Chopped slices are blended with cream cheese and used as sandwich spread.
- Peeled, diced fruits, with diced onion, breadcrumbs, butter and appropriate seasonings are employed as stuffing for roast lamb.
- Tree tomato slice, alone, or combined with sliced apple, are cooked in pies. They may be packed in preserving jars with water or sugar syrup and cooked for 55 minutes, or may be put into plastic containers with a 50% syrup and quick-frozen for future use in pies or puddings.
- The peeled fruits can be pureed in a blender or by cooking, strained to remove the seeds and then packed in plastic containers and frozen. Lemon juice may be added to the puree’ to enhance flavor. The peeled, stewed fruits are combined with gelatin, milk, sugar and lemon juice to make a dessert which is then garnished with fresh tree tomato slices. Peeled, sliced and seeded tree tomatoes, with lemon rind, lemon juice and sugar, are cooked to a jam; or, with onions and apples, are made into chutney.