The tomato originated in Central and South America and is related to the potato plant. Due to it being a sub-tropical plant, the tomato requires warm conditions for growth, and it is very susceptible to frost damage. Maximum plant growth, flower formations and fruit production take place when the average daily mean temperature is between 20 °C – 24°C. Temperatures below 12°C and above 35°C have a detrimental effect on fruit set and fruit quality.

The tomato is a popular fruit and is grown both on farms and in market gardens. There is a good demand for first grade tomatoes on the fresh fruit market, and the market price varies according to the supply which, in turn, is affected by the climate. Heavy rains in the summer and severe frost in the winter reduce the supply and increase the price. Tomatoes are also produced for canning, and these crops are grown under contract to one of the food processing firms in the country. Usually this is an excellent arrangement because the farmer receives a fixed price and a guaranteed market for his crop.

The main summer crop is produced in areas above 1 000 metres in altitude and where the average rainfall is not more than 1 000 mm per year. A winter crop can be grown in frost-free areas below I 000 metres in altitude, although small scale growers can grow all year round. These producers keep up a succession of small plantings throughout the year in order to catch the high seasonal prices, but the main crops grown by the larger producers are as follows:

Cool regions: planting times are between September – November, with an ideal planting time in October.

Warm regions: planting times are between August – December with an ideal planting time between September – November.

Hot regions: planting times are between January – July with an ideal planting time between February – July.

Figure 1: The Tomato Plant

Source: adamdalpozzo


Before deciding which variety to grow, in fact before deciding to grow the crop at all, the producer should study the market and decide which type of customer he intends to supply. In general, the choices are:

  • To produce large tomatoes that can be sliced and used for cooking. Bought and used mainly by the catering trade, hotels, cafes, etc.
  • To produce smaller tomatoes which are more convenient and attractive for pre-packing. These are bought for households through the supermarkets and other retail outlets.
  • To produce tomatoes for canning or manufacture. These are grown on contract and this should be negotiated before the crop is planted.


Mananpal: Attractive, firm, well coloured fruit, and provides a high yield. This variety is partlyresistant to Fusarium Wilt (fungal disease).

Moneymaker : A medium size, round, well coloured, firm fruit. It gives a high yield and the fruit isless prone to cracking than other varieties. The fruit has a strong skin which makes it suitable for packing and transport.


Roma: Short, bushy plants which produce a moderate yield. The fruit is small to medium in sizeand has a plum like shape. Resistant to nematodes and red spider mite.

Rossol: It has a determinate growth characteristic with medium to large fruit, with a pear likeshape. Resistant to nematodes, altenaria blight and red spider mite.

Figure 2 and 3: Moneymaker tomato variety (left) and Roma tomato variety (right)

Source: gardensite                                                     Source: kathdedon.wordpress

Pots/seedling trays: A mixture of one part of compost and four parts of soil should be used tofill the pots, with fertilizer and magnesium limestone added at the same rate as for seedbeds. The potting mixture should be fumigated against eelworms. Two seeds should be sown in each pot, and the weaker of the seedlings removed after germination. The pots should be kept moist but not over watered.

Figure 4 and 5: Seedling trays (left) and Seedlings in a pot (right)

Source: beechstreetgardens.blogspot                                        Source: playtogrow


The seedbeds should be well watered just before planting the seedlings out. The plants can be lifted with a trowel, keeping a ball of soil around the roots, and placed in boxes for transporting to the land where they are planted by hand (transplanted). This is done when the plants are about 150 mm in height. Great care should be taken to handle the plants as little as possible, as damage even to the hairs on the stem can allow Bacterial Canker to infect the plant. When planting out from pots or seedling trays, the plastic is torn away leaving the plant and the soil around the roots undisturbed. It is possible to plant out from pots without touching the plant. Plants should be 300 – 500 mm apart, and in rows which are 1,5 – 2,5 metres apart. A common practice is to ridge the land before planting out. After planting, each plant should be well watered, and a second watering given after 5 – 6 days. Once the plants are established, watering or irrigation can be done every 14 days, but once the lower fruit truss has half developed, water should be given more often. Water should be applied to the bottom of the plant, as wetting the stem and leaves encourages disease.

Staking and Trellising: The tomato is a tall growing plant which produces a mass of heavy fruiton the stems so that each plant must be supported during the growing and fruiting period. Otherwise, the plant will lie along the ground and both the plant and the fruit will become diseased and will rot. The methods recommended for supporting tomatoes are the following:

Staking: A thin stick is planted next to each plant, and as the plant grows, the stem and sideshoots are tied to the stake with string. This is a simple but laborious method, and is suitable for small areas of the crop.

Single Wire System: With this system, posts are set into the ground before the crop is plantedout. These should be 1,5 metres high and spaced 4,5 metres apart. Two lengths of thin fencing wire are stretched along the rows and fastened to each post, the bottom wire being 150 mm above the ground, and the top wire 1,5 metres high. A string is tied between the wires beside each plant, and as the plant grows the stem is twisted around the string. Extra strings may be needed for the side shoots. This system requires a lot of labour, and the string can only be used for one season.

Figure 6: A single wire system for trellising tomato plants

Double Wire System: The posts are set up as for the single wire system, before the crop isplanted out and double wires are stretched between the posts, one on each side. These are spaced at 0,3 metres up the posts, so that 5 double wires are needed to support the plant when it is fully grown. The plants are trained to grow between the wires. This is the most popular method used, and the posts and wire can be used for many crops of tomatoes. Some varieties of canning tomatoes have short, bushy plants and these can be grown without staking.


Nitrogen, Phosphate Potash and Magnesium are important major nutrients for the tomato crop. However, too much nitrogen applied in the early life of the plant will produce too much leaf and poor quality fruit. Lack of phosphate will cause poet growth and fruit production, and lack of potash causes slow ripening and poor colouring of the fruit.

Where possible, the land for tomatoes should be given a dressing of organic manure such as kraal manure, pig or poultry manure. This can be applied at the rate of 25 to 35 tons per hectare and ploughed into the soil. Where organic manure is applied the quantity of fertilizer can be reduced, particularly the nitrogen. The following fertilizer dressings are recommended:

  • Seedbed: fertile soils: apply 500kgs/ha of 2:3:4(30). Infertile soils: apply 1 000 kgs/ha of

2:3:4(30). These dressings should be applied to the land before planting out, and disced or worked into the soil.

  • Topdressing: Fertile soils: apply 250kg/ha of LAN at 3 and 6 weeks. Apply 100kgs/ha of KNO

at 6, 9 and 12 weeks. Infertile soils: apply 200kgs/ha of LAN at 3 and 6 weeks. Apply 100kgs/ha of KNO at 6, 9 and 12 weeks. This can be sprinkled around the bottom of each plant, or it can be applied in the irrigation water.


Tomatoes are subject to a number of pests and diseases, and the following precautions should be taken when growing the crop.

  • Use healthy seed obtained from a reliable source. Home produced seed should be saved from healthy, high yielding plants.
  • In the seedbed always:

Select a fresh site for each crop, and clear all weeds from around the site before sowing, and make sure the soil is well drained.

Fumigate the seedbeds with a nematicide to kill eelworms, certain other soil borne diseases and weeds.

Sow the seed thinly in rows rather than broadcasting.

No smoking of snuff allowed in the seedbeds. Wash hands before entering the area and handle seedlings as little as possible. Never move from working with a mature crop to working in the seedbeds.

  • Never transplant weak or diseased seedlings.

All crop residues should be burned after harvesting. Where diseases have occurred, all equipment, hoes, trowels, stakes, etc, should be treated with creosote or a solution of 2% formalin.

Sound crop rotation should be followed. 3 To 4 years should be the length of time between tomato crops on the same land. Never grow tomatoes in the same rotation as potatoes or tobacco, as these suffer from many of the same pests and diseases.

Follow good cultural practices by avoiding waterlogged areas for the crop, planting the young plants on ridges and supporting them with stakes or wire. Use well balanced mixtures of fertilizer and correct irrigation or watering; where possible avoid using overhead irrigation.

  • Inspect crops carefully for signs of disease, and follow a spraying programme of fungicides and insecticides.

Captab mixed at the rate of 200 grams per 100 litres of water or Chlorothalonil mixed at a rate of 100 ml/100 litres water and used to prevent Late and Early Blight and Septoria Leaf Spot.

Copper Oxychloride mixed at the rate of 5 grams per litre and used to prevent bacterial spot. Benomyl mixed at the rate of 50 grams per 100 litres of water and used against Mildew.

Abamectin are used to control mites and red spider, and in the past D.D.T. have been used to kill caterpillars and cutworms. As D.D.T. is now regarded as an undesirable chemical, a substitute should be used.


Root Knot nematode: Plants become dwarfed and lose their leaves. Small knot-like swellings can be seen on the roots. Prevention is by fumigation, one can use crop guard which can be applied in many different ways.

Cutworms: Dark brown caterpillars which eat through the stems at ground level. A chemical controlfor cutworms is carbaryl or trichlorfon.

Figure 8 and 9: A cutworm (left) and cutworm damage (right)

Source:                        Source: .highdesertgarden

Caterpillars: Eat the leaves and fruit on mature plants. Spray regularly with Thiodan.

Red Spider Mite: Leaves become mottled and yellow, with a fine web on the undersides of theleaves. Spray with Abamectin

Figure 10 and 11: Red spider mites

Source: flickr                                                                                Source: commons.wikimedia

Tomato Russet Mite: Leaves develop a silvery sheen. Fruit turns yellow and drops off the plant.

A chemical spray with Abamectin can is used.


Bacterial Canker and Bacterial Spot: Wilting of foliage, splitting of the stems and spots orpustules on the fruit. These are seed-borne diseases and can be prevented by using good seed and handling the plants as little as possible.

Figure 12 and 13: Bacterial Canker

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Early and Late Blight: These are fungal diseases causing yellowing of the leaves and defoliation.

Spray with a fungicide such as Captab.

Figure 14 and 15: Late blight

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Figure 16 and 17: Early blight

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Mosaic and Bunchy Top: These are virus diseases which can be prevented by using good seedand by practising good hygiene in the seedbeds. Severe attacks of these diseases can cause complete crop failures.

Alternate with a variety of fungicides so that there is no build up of resistance to chemicals


Blossom End Rot: causes brown markings at the ends of the fruit. This disorder is caused by poor irrigation and the soil going from very dry to very wet.

Cracking: of the fruit is also caused by variations in soil moisture.

Puffiness: of the fruit which feels light in weight and soft. This is encouraged by highapplications of nitrogen to the crop.

Sunscald: The exposed side of the fruit stays yellow, or it can become white and blistered. Thiscan happen if the plants lose their leaves or collapse because of poor staking.

Figure 18 and 19: Blossom end rot on tomatoes

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Figure 20 and 21: Cracking of tomatoes

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Figure 22 and 23: Sunscald

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There are four stages at which tomatoes can be harvested, and the stage of picking will depend on the season and the market to which they are being sold.

Pale Blossom End: Cream coloured streaks appear at the blossom end, which is the end of thetomato away from the stalk. If picked at this stage, the fruit will last at least a week before being fully ripe.

Pink Blossom End: Pink or red colour appears at the blossom end. The fruit will be fully ripe in about4 days after picking.

Pink Stage: The fruit are a pink colour all over and are 1 – 2 days from fully ripe.

Ripe Stage: The fruit are red and ripe, but still firm, and should be marketed immediately. Onlysound, clean tomatoes should be marketed, and they should be graded into equal sizes and colour. Fruit should be packed into standard wooden or cardboard boxes measuring 460 x 230 x 100 mm and holding 5 kgs of fruit.

Yields: of 40 – 50t/ha are common and can be up to 80t/ha.

Figure 24: Ripening of tomatoes