TREE TOMATO (TAMARILLO)

By Hellen Omondi

Introduction

Tree tomato also known as Tamarillo is an egg-shaped edible fruit. The fruit contains high levels of fiber, vitamin A, B, C E and K and minerals, specifically iron, calcium, magnesium, potassium, phosphorous and is low in calories. It is an important source of pectin, carotene, and protein. Vitamin C, E and B-carotene (pro-vitamin A) are regarded as major nutritional antioxidants.

Utilization: The tree tomato flesh can be added to stews to make unique flavour. Fruit can be eaten fresh, cooked, made into jam chutneys or blended with other fruit juices e.g. orange juice to make refreshing juice or added to vegetable salads. The yellow variety is preferred for processing. The fruits should not be cut on wooden or other permeable surface as the juice will make an indelible mark. The fruits are high in pectin and therefore have good properties for preserves. The unripe fruit contains high level of tannin, thus bitterness.

Potential for production

There is high demand for the fruit especially in the urban market in hotels, supermarkets, local markets and with food vendors. Consumers are increasingly becoming aware of the nutritional and medicinal properties of the fruit hence the current supply cannot meet the demand due to limited production at commercial level within the country. The fruit can be grown in a wide range of climatic zones, it requires minimal input and is easy to manage once established.

Varieties: The colour of fruits varies from yellow and orange to red and almost purple. Sometimes they have dark, longitudinal stripes. Red fruits are more acidic, yellow and orange fruits are sweeter. Some varieties grown include: Ecuadorian orange, Gold mine, Inca gold, Red oratia , Rothame, Ruby red,  Solid Gold, Yellow.

Ecological Requirement

Altitude: The favourable production altitude in Kenya is 1000-2000m above sea level. However it can be grown up to 3000m above sea level. The fruit is slow to ripen in higher altitudes.

Rainfall: It requires rainfall 1200 - 2100 mm and cannot tolerate drought.  

Soils: Tamarillos requires well drained fertile soils that are rich in organic matter. The tree does not tolerate water logging because of the shallow root system. Soil pH of 5-8.5 are suitable for production.

Temperatures: Tamarillos prefer warm conditions as long as the plants are also provided with sufficient moisture. Temperatures should be above 10°C throughout the year. Persistent heavy frosts can kill even well-established trees.

Planning for production

• Selection of suitable site with required condition
• Selection of species depending on market requirement
• Organizing for planting material from a registered nursery

Note: The area under production should be set aside and expanded gradually so that production is increased according to market demand.

Tree tomato can be grown in the open field and also in the green house.

Land Preparation

Land should be prepared to a fine tilth and manure incorporated into the soil. This reduces or eliminates the need to apply fertilizer. In poorly drained soils ridges prepare for planting.

Propagation: Seeds and cuttings may be used for propagation.

Seeds: Seeds produce high-branched, erect tree. The tree does not always come true to type from seed, but is possible if seed is taken from red fruits with black seed pulp or yellow fruits with yellow seed pulp. Seed should be separated from pulp, washed and dried in the shade. Germination is accelerated by placing washed and dried seed in a freezer for 24 hours before planting out. Seeds- produce a high–branched erect tree ideal for sheltered locations; seeds germinate in 3-5 weeks.

Cuttings: Cuttings develop into a shorter, bushy plant with low–lying branches suitable for exposed windy sites. Cuttings should be from 1-2 years-old wood, 10-30 mm thick and 45-100 cm long.

Planting: The spacing in the field varies depending on the management practices, soil fertility and environmental conditions. The spacing is 2.5 -3 m apart between plants and 3 m between the row or 1.0-1.5m between plants and 4.5-5.0m between rows. Closer spacing is recommended in windy unprotected locations.

Manure and Fertilizer

A compound fertilizer such as NPK may be applied at planting time if necessary; however a good supply of compost is normally adequate.

Wind break: Tree tomato is fragile and is shallow rooted hence requires protection from wind because branches can easily break. Staking can be done to prevent swaying and to minimize root disturbance.

Pruning: The tree should be pruned back the first year after planting to a height of 0.9-1.2 m to encourage branching. Pruning helps to control fruit size, plant size and harvesting. If timed properly pruning can extend the total bearing period. Yearly pruning is therefore recommended to eliminate old branches that have already fruited because fruits are normally produced on new growth. Light pruning leads to medium sized while heavy pruning leads to large sized fruits. Basal shoots should be removed. In the green house pruning prevents excessive vegetative growth.

Weeding

Tamarillo is shallow rooted hence care should be taken when weeding the plant to avoid damaging the roots. Deep cultivation around the plants should also be avoided

Irrigation

The plant cannot tolerate prolonged drought and should have sufficient water during dry periods.  Supplement irrigate during dry periods especially at peak growth. Mulching is very beneficial in conserving moisture and also suppressing weeds.

Pests and Diseases

The plant belongs to solanaceae family and is related to potatoes, tomatoes, brinjals. These tend to suffer from the same pests and diseases, however tree tomatoes are generally pest and disease tolerant but occasional attacks of green aphids thrips and red spider mites and fruits flies.

The principal disease is powdery mildew which may cause serious defoliation if not controlled. Other diseases during growth include potato virus, cucumber mosaic virus and downy mildew. The fungal diseases (powdery mildew, downy mildew) can be controlled using suitable fungicides. Viral diseases can be prevented by controlling vectors e.g. aphids and fields sited away from host plants such as cucumber, potatoes

Harvesting

Tree tomatoes are ready to harvest when they develop red or yellow colour. The tree is a fast-growing, starts bearing fruits from 1.5-2 years after planting and bears fruits all year round. Fruiting should be discouraged at one year since this retards growth. Peak production is reached after 4 years and it continues for 5-6 years with good management.  The economical life span of the tree is about 11-12 years.

Yields: The average yield is15-20 kg per tree annually or 15-17 tons per hectare.

Storage: At room temperature the fruit can be stored for about 1 week, but under controlled storage it lasts for more than 2 months. The fruits ripens over a period of 6-7 weeks depending on environmental conditions hence can be left on the tree without rotting as the grower organizes for better market.

Challenges: Lack of adequate clean planting material is a serious challenge in production. Propagation is by use of cuttings or seeds from the locally planted trees. This may lead to disease transfer if cuttings or seed are obtained from unhealthy plants. Care should be taken while sourcing for planting material.

Note: Planting material should be obtained from registered tree nurseries.

Advice to potential growers

This enterprise is growing with high prospects due to increased demand for the fruits. Market supply is low hence the price of fruits is very high. Growers can organize for collective production within an area to ensure consistence supply and production for the targeted market. Value addition through juice making is an added advantage in marketing.  The relatively costs of orchard establishment is low, however it requires careful management to ensure high quality yields.