Tomato(Solanum lycopersicum L.) is one of the most widely grown vegetables in the world. It is very popular among consumers and is commonly used as a salad vegetable in raw form. The fruits are also processed into juice, ketch-up, sauce, soups, etc. It is the most extensively canned vegetable. Tomatoes form an important source of vitamins A and C in diets.
Interestingly, tomato is one of the newest plants to be used on a large scale for human consumption. It was once believed to be poisonous and was more used an ornamental plant. The perceived poisonous nature of tomato was due to its association with many toxic plants. Tomato is a member of the family Solanaceae, commonly referred to as the ‘deadly nightshade’ family because it has many poisonous members, several of which produce toxic alkaloids. It was only after 1820, when Colonel Robert Gibbon Johnson disproved the myth during a public demonstration in New Jersey; tomato acquired the status of a valuable food item.
Tomato is a short lived perennial plant, grown as an annual, typically growing 1-3 m in height. The stem is weak, woody and the plant usually scrambles over other plants. The leaves are long, pinnate, with 5–9 leaflets, and with serrated margin. Both the stem and leaves are densely glandular and hairy. The flowers are bisexual in nature, off white or yellow coloured, and are borne in groups of 3–12. Tomato is a self-pollinated crop. Fruit size ranges from 2 cm in diameter (cherry tomatoes) to over 15 cm (beefsteak tomatoes). The most widely grown commercial tomatoes tend to be in the 5–6 cm diameter range. Fruit color ranges from yellow to orange to deep red depending on the accumulation of a carotenoid pigment, lycopene. Fruit shape ranges from ovals to plum shaped Italian plum tomato, to pear shaped tomatoes. Fruit flavour also varies from very sweet to highly acidic.
Different types of tomatoes are available for cultivation. Selecting the right variety is critical and should be based considering many factors including the growing condition and market demand. Based on the growth habit, tomato varieties are of three types viz., determinate, semi determinate and indeterminate. Determinate and semi determinate varieties produce stems that end with a flower cluster. Determinates are short and bushy while semi determinate varieties grow slightly taller. Indeterminate varieties continually produce new leaves and flowers, and can grow very tall. Indeterminate varieties set fruit over a longer period. This longer harvest period is an advantage if market prices fluctuate, because income tends to even out. Indeterminate varieties should be staked and pruned and usually require more labour.
Three major market classes are important for tomato viz., fresh market, cherry and processing varieties. The fruits of fresh market varieties are usually red but vary in colour, shape, and size; the cherry types are small fruited (less than 30g) borne on long clusters and used as fresh market type; and processing varieties with fruits having intense red color and high solids content suitable for making paste, ketchup, or sauce.
Origin and distribution
The centre of origin of tomato is South America and the plant is specifically native to the Andes region of Chile, Colombia, Bolivia, and Peru. Mexicans were the first to domesticate tomato, and though cultivated throughout the world, the crop is particularly concentrated in Australia, Central America, and South America.
Climate & Soil
Tomato is a warm season crop. The best fruit colour and quality is obtained at a temperature range of 21-24°C. Temperatures above 32°C adversely affects the fruit set and development. The plants cannot withstand frost and high humidity. It requires a low to medium rainfall. Bright sunshine at the time of fruit set helps to develop dark red coloured fruits. Temperature below 10°C adversely affects physiological activities. Wide ranges of soils from sandy to heavy clay are suitable for growing tomato. However, well-drained, sandy or red loam soils rich in organic matter with a pH range of 6.0-7.0 are considered as ideal. Tomatoes benefit from crop rotation. However, avoid planting tomato in a field planted the previous season with tomato, chilli, brinjal, or other solanaceous crop as these crops share some pest and disease problems.
Bacterial wilt resistant variety from the Kerala Agricultural University (KAU). Fruits are round, slightly flat at the ends and medium sized. Fruits show tendency to crack at maturity and hence should be harvested before full maturity.
Bacterial wilt resistant variety from the KAU. Fruits are round, slightly flat at the ends, medium sized and light greenish in colour. Average yield is 43.5 t/ha.
Bacterial wilt resistant variety from the KAU. The variety is resistant to fruit cracking, and tolerant to leaf curl and mosaic. Fruits are reddish round without green shoulder. Average fruit weight is 45 g and average yield is 30 t/ha.
High yielding variety is released by IARI, New Delhi. It is an early growing cultivar. Fruits are yellow coloured at stem end, and are of uniform ripening. Average yield is 32.5 t/ha. It is suitable for table as well as processing purpose.
Pusa Early Dwarf
Variety released by IARI, New Delhi. It is an early ripening cultivar of determinate type; fruits are flattish round, medium large with yellow stem end. Fruits are ready for harvesting 75-80 days after transplanting. Average yield is 35 t/ha. It is suitable for table as well as processing purpose.
Variety released by TNAU, Coimbatore. Suitable for growing in South India. Fruits are round with yellow stem end, determinate and ripen uniformly.
Hybrid variety released by IIHR, Bangalore. Plants are determinate. Fruits are large (120g) square to round with light green shoulder. Suitable for table purpose. Resistant to bacterial wilt. Crop matures in 130 days. Average yield is 46 t/ha.
High yielding hybrid variety released by IIHR, Bangalore. Plants are semi determinate with light green foliage. Fruits are medium large (70-75 g), and round with light green shoulder. Fruits are firm with good keeping quality (17 days) and long transportability. Suitable for both fresh market and processing. Resistant to bacterial wilt. Crop matures in 140 days. Average yield is 76 t/ha.
High yielding hybrid variety released by IIHR, Bangalore. Plants are semi determinate with dark green foliage. Fruits are round, medium large (65-70 g) with green shoulder. Fruits are thick fleshed with good keeping quality (17 days) and long transportability. Suitable for table purpose. Resistance to bacterial wilt. Crop matures in 140 days. Average yield is 65 t/ha.
Bacterial wilt resistant variety.
Propagation & Planting
Recommended seed rate for tomato is 400g/ha. Prior to sowing, treat the seeds with Trichoderma viride (4 g/kg of seed) or Thiram (2g/kg of seed) to avoid damage from damping off disease.
Tomato is a transplanted vegetable. Seeds are sown in the nursery and one month old seedlings are transplanted to the main field. For sowing the seeds, raised seedbeds of 90 to 100 cm width and of convenient length are prepared to which well decomposed organic matter has been incorporated. After sowing the seeds, mulch with green leaves and irrigate with a rose can daily in the morning. To avoid mortality of seedlings due to damping off, drench the seedbed first with water and then with Bavistin (15-20 g/10 litres of water). Remove the mulch immediately after germination of the seeds. Restrict irrigation one week before transplanting and irrigate profusely on the previous day of transplanting.
Land preparation and transplanting
Transplant the seedlings during October-November for an irrigated crop. Prepare the land to a fine tilth and incorporate well rotten organic manure. Give a pre-sowing irrigation 3-4 days prior to transplanting. Seedlings with 5-6 true leaves can be used for planting. Before planting, dip the seedlings in a solution prepared by Rogor (1.5ml/litre) and Dithane M - 45 (2.5g/litre) for 5-6 minutes. The seedlings are transplanted in shallow trenches or pits. Transplanting should preferably be done in the evening and the seedlings may be given temporary shade for three to four days during hot days.
Transplant the seedlings at 60 x 60 cm.
Apply well rotten farmyard manure or compost @ 20-25 t/ha at the time of land preparation and mix well with the soil. A fertilizer dose of 75:40:25 kg N:P2O5:K2O / ha may be given. Half the dose of nitrogen, full phosphorus and half of potash may be applied as basal dose before transplanting. One fourth of nitrogen and half of potash may be applied 20-30 days after planting. The remaining quantity may be applied two months after planting.
Application of growth hormone to tomato crop has been recommended for improving seed germination, to enhance flowering and fruit set, for faster and uniform fruit ripening; and for realizing higher yield. The growth regulators commonly used for tomato, their dosage and effect of application are detailed in the table below.
Tomato crop responds well to irrigation. Flowering and fruit development are the critical stages of irrigation for tomato and therefore water stress should be avoided during these periods. Provide light irrigation 2-3 days after transplanting. Avoid heavy irrigation especially after a long spell of drought as it causes cracking of the fruits.
Field should be kept weed free, especially in the initial stages of plant growth, as weeds compete with the crop and reduce the yield drastically. Providing 2-3 hoeing at regular interval helps to keep the field free from weeds and facilitates soil aeration and root development. Deep cultivation, on the other hand, injures root system and expose moist soil to the surface. Weeding can be combined with fertilizer application and earthing up and can be done at one and two months after transplanting. Pre emergence application of basalin (1 kg a.i./ha) or pendimethalin (1 kg a.i./ha), coupled with one hand weeding 45 days after transplanting is also effective for controlling weed growth. Another way to control weed growth is by mulching with black or transparent sheet plus use of herbicides such as pendimethalin (0.75 kg a.i./ha) or oxyfluorfen (0.12 kg a.i./ha).
Crop rotation and intercropping
Continuous cropping of tomato in the same field should be avoided as it results in build up of pests and diseases. At least one year gap should be given between two successive tomato crops or other solanaceous crops like chilli, brinjal, etc. However, cereals like rice, corn, sorghum, millets, etc. and crops like watermelon, groundnut, safflower, sunflower, sesame and marigold can be successfully grown after tomatoes. Tomato also fits well as an intercrop in different cropping systems of cereals, grains, pulses and oilseeds; and cropping systems like rice-tomato, rice-maize are popular.
Stake the plants depending on the growth and bearing habit of the variety. Staking is essential for hybrids because of their tall growing habit and heavy bearing nature. Also, staking facilitates intercultural operations and helps in maintaining the quality of the fruits. Staking should be done 2-3 weeks after transplanting either by wooden stakes or laying overhead wires to which individual plant can be tied. In the case of indeterminate types, two or three wires are stretched parallel to each other along the row and plants are tied to these wires.
Tomato fruit worm (Heliothis armigera)
Caterpillars feed on leaves and other vegetative parts in the initial stage. Later cause extensive fruit damage by entering through cut holes and burrows and feeding the internal content. Infestation is severe during October-March.
Control: Judicious use of synthetic pyrethroids like fenvalerate (50g a.i./ha) or deltamethrin (10g a.i./ha) controls the fruit borer.
Epilachna beetles (Epilachna vigintioctopunctata)
The yellowish grubs and adults feed voraciously on the leaves and tender parts of the plant, and completely skeletonizes the leaves leaving only a network of veins. The pest often causes serious defoliation when appeared in large number.
Control: Collection and destruction of infested leaves along with the grubs, adults and eggs reduces the pest incidence. Spraying malathion (2ml/litre of water) or carbaryl (2-4 g/litre of water) effectively controls the pest.
Jassids (Amrasca biguttula biguttula, Cestius phycitis)
Nymphs and adults of the pest suck sap from the lower surface of the leaves and infested leaves curl upward along the margins, turn yellowish and show burnt up patches. Fruit setting is also adversely affected. The pest is the natural vector of mycoplasmal disease like little leaf and viral disease like mosaic.
Control: Spray malathion (0.1%) or dichlorvos (0.05%) 20 days after transplanting.
Tabacco caterpiller (Spodoptera litura)
Caterpillars feed gregariously on tender leaves, shoots and fruits at night. The pest is confined to nursery beds and assumes cutworm habits. The adult moths are greyish brown coloured with white marking on upper wings.
Control: Spray nuvan (0.5 ml/ 2 litres of water). Avoid the use of highly toxic insecticides.
Whitefly (Bemisia tabaci)
Minute milky white flies and their nymphs suck cell sap from the leaves. The affected leaves curl and dry up, and growth of the plant is stunted. White flies act as a vector of leaf curl virus causing severe yield loss.
Control: 2-3 sprayings with dimethoate (0.05%) at fortnightly intervals starting with the appearance of the pest also effectively control the pest.
Mites (Tetranychus cucurbitae)
Nymphs and adults suck cell sap from the foliage and flower buds. White patches appear on the affected leaves. The leaves later become mottled, curl, turn brown and fall. Different stages of mite are found in colonies covered by white silky webs on lower surface of leaves. Low relative humidity favours mite multiplication.
Control: Proper irrigation and clean cultivation practices including cutting and burning of severely infested plant parts help to keep the pest population under control. Acaricides like dicofol (0.05%) and wettable sulphur (0.3%) gives effective control of mites.
Root knot nematodes (Meloidogyne spp.)
The nematodes invade the roots of tomato forming characteristic galls on roots. The symptoms of aerial infection include stunted plant growth, chlorosis and tendency to wilt under moisture stress during hot, dry weather. When the nematode population is high, plants of a susceptible variety may die before reaching maturity.
Control: Complete elimination of nematodes from field is not possible. However, use of resistant varieties and crop rotation with non host crops like marigold, maize, onion, etc. reduces the nematode infestation. Application of neem oil cake (1-1.5 t/ha) 15 days after transplanting also helps to suppress the nematode population.
Bacterial wilt (Pseudomonassolanacearum)
It is one of the most serious diseases of tomato crop. High soil moisture and soil temperature favour disease development. Characteristic symptoms of bacterial wilt are the rapid and complete wilting of normal grown up plants. Lower leaves may drop before wilting. A white streak of bacterial ooze comes out when infected plant parts are cut and immersed in clear water.
Control: Uproot and destroy the plants affected by bacterial wilt. Cultivate resistant varieties like Sakthi, Mukthi and Anagha and crop rotation with non host crops is also recommended in bacterial wilt prone areas. Seedling treatment with streptocycline (1 g/40 litres of water) for 30 min protects the seedlings in the initial stages of growth.
Damping off (Pythium aphanidermatum)
A serious disease in the nursery. High soil moisture, moderate temperature and high humidity especially in the rainy season favour the disease. Two types of symptoms are observed, viz., pre emergent and post emergent damping off. The pre emergent damping off results in rotting of seed and seedling before emerging out of soil, whereas in the post emergent damping off, seedlings after emergence are infected near the collar region at ground level. The infected tissues become soft and water soaked. The collar portion rots and ultimately the seedlings collapse and die.
Control: Avoid continuous raising of nursery in the same plot. Sow the seeds as thin as possible in the raised beds prepared in the open area during summer months. Use healthy seeds treated with thiram (2g/kg of seed) for sowing. Soil solarization by spreading 250 gauge polythene sheet over the bed for 30 days before sowing and application of biocontrol agent Trichoderma viride in soil @ 1.2 kg/ha is also found effective to considerable extent. Spray nursery and main field with 1% bordeaux mixture at monthly intervals.
Early blight (Alternaria solani)
Serious foliage disease characterized by the appearance of leaf spot and leaf blight. Symptom starts as small, black lesion, usually on the older leaves, which later enlarge with concentric rings in a bull’s eye pattern, with the surrounding tissue being yellow in colour. High temperature and humidity favour the disease and result in serious damage to foliage. Stem infestation show girdling of the plant near the soil resulting in death of the plant. Infected fruits show lesions and concentric rings.
Control: Removal and destruction of the affected plant parts and crop rotation helps to minimize the disease incidence. Spraying the crop with dithane M-45 (0.2 %) or bavistin (0.1 %) is recommended for effective disease control.
Buck eye rot (Phytophthora parasitica)
A serious disease in tomato growing tracts. The pathogen attacks only fruits and does not affect the foliage thus differing from late blight. Disease starts as greyish green or brown water soaked spot on lower fruits that touches the soil, which later enlarges forming concentric rings of alternately dark brown and light brown bands. Affected young green fruits become mummified.
Control: Providing good drainage, staking plants and removing foliage and fruits up to a height of 15-30 cm from ground level helps to control the disease. Spraying with dithane M-45 (0.2 %) four times at an interval of 10 days effectively controls the disease.
Late blight (Phtophthora infestans)
Symptoms usually begin on the shoulders of the fruit as large, green to dark brown lesions, which later turn brown destroying large areas of tissue. White mouldy growth appears on the lower leaf surface and fruits. Humidity coinciding with mild temperatures for prolonged periods favours the disease development causing severe economic losses.
Control: Follow crop rotation with non host crops and avoid planting tomatoes near potatoes. Select disease free seeds and seedlings for planting. Treat the seed with thiram (2-3 g/kg of seed) before planting. Spray dithane M-45 (2 g/kg of seed) at 15 days interval, starting from 30 days after transplanting.
Fusarium wilt (Fusarium oxysporum lycopersici)
It is a serious disease affecting young seedlings in the nursery and main field. Symptoms start as clearing of the veinlets and chlorosis of the leaves. Soon the petiole and the leaves droop and wilt. The younger leaves may die in succession and the entire plant may wilt and die in a course of few days. In main field, lower leaves of seedlings become yellow, wilt and die.
Control: The nursery should be regularly inspected and wilt affected plants should be removed and destroyed. Prior to planting, the beds should be drenched with carbendazim (0.1%) and the seeds should be treated with the thiram (2.5 kg/ha). Crop rotation with non host crops like cereals helps to reduce the disease inoculum.
Powdery mildew (Leveillula taurica)
The disease occurs severely during dry seasons. A white powdery coating of the fungal growth appears on the leaf surface. Infected leaves may be stiff, narrow and smaller in size. The fungus progressively attacks new leaves, spreading over leaf stems, twigs, and even the fruit. Terminal growth of the affected shoot is stunted or killed. The fruit yield is reduced and the affected fruit are smaller in size.
Control: Spraying with karathane (0.1%) or wettable sulphur (3 g/ litre of water) twice at an interval of 10 days helps to control the disease.
Tomato mosaic virus (TMV)
The disease is characterized by light and day green mottling on the leaves often accompanied by wilting of young leaves in sunny days. The leaves are usually distorted, puckered and smaller than normal. The affected plant appears stunted, pale green and spindly. The virus spread through implements and plant debris.
Control: Select seeds for sowing from healthy plants. Soaking of the seeds in a solution of trisodium phosphate (90 g/litre of water) a day before sowing helps to reduce the disease incidence. The seeds should be thoroughly rinsed and dried in shade. In the nursery all the infected plants should be removed carefully and destroyed. Crop rotation with crops other than tobacco, potato, chilli, capsicum, brinjal, etc. should be undertaken.
Tomato leaf curl virus (TLCV)
One of the most devastating diseases of tomato transmitted by whitefly. The disease is characterized by severe stunting of the plants with downward rolling and crinkling of the leaves. The newly emerging leaves exhibit slight yellow colouration and later show curling symptoms. Older leaves become leathery and brittle. The infected plants look pale and produce more lateral branches giving a bushy appearance. The nodes and internodes are significantly reduced in size and the plants remain stunted.
Control: Removal and destruction of affected plants and removal of alternate and collateral hosts harbouring the virus provide good control. Two to three foliar sprays with dimethoate (0.05%) at 10 days intervals are effective. Raising 5-6 rows of boarder crops all around the tomato plot 50-60 days before planting tomato checks incoming whiteflies from entering into tomato crop minimizing the disease spread. Mulching the soil just before transplanting with white, blue, grey or black polythene sheets just before transplanting of tomato is also found effective.
Tomato spotted wilt virus (TSWV)
Numerous small, dark, circular spots appear on younger leaves. Leaves may have a bronzed appearance and later turn dark brown and wither. Fruits show numerous spots with concentric, circular markings. On ripe fruit, these markings appear as alternate bands of red and yellow. The spotted wilt virus is transmitted through thrips.
Control: Removal and destruction of affected plants and separativng and removal of alternate and collateral hosts harbouring the virus provide good control. Checking the population of thrips by giving two to three foliar spray using dimethoate (0.05%) at 10 days intervals reduces the disease incidence.
Anthracnose (Colletotrichum phomoides)
Fruit show small, slightly sunken, water soaked spots, which later enlarge, become darker in colour, depressed and have concentric rings. Under warm and humid conditions, the fungus penetrates the fruit, completely destroying it. Mature fruits nearing maturity are more susceptible to the disease.
Control: Providing adequate drainage, crop rotation and a prophylatic fungicide spray can control the disease.
Blossom end rot
Blossom end rot is a physiological disorder of tomato that can appear as water soaked spots on the blossom end of the fruit. These spots later enlarge and become black. Deficiency of calcium in the developing fruit, extreme fluctuations in moisture, root pruning and excessive nitrogen fertilization result in blossom end rot.
Control: Avoid excessive application of nitrogen particularly in ammoniacal form. Application of lime or calcium based fertilizers like calcium ammonium nitrate as basal dose reduce this physiological disorder. Foliar spray of calcium chloride (3 g/litre of water) also controls this disorder.
Tomato fruits nearing maturity when exposed to the sun show scald with blistered water soaked appearance. Rapid desiccation leads to sunken area, which usually has white or grey colour in green fruit or yellowish in red fruits. Any factor causing a loss of leaves, such as disease, will expose fruits to sunlight and increase chances for sunscald.
Control: Covering exposed fruits reduce the incidence of sunscald.
Cracks results from extremely rapid fruit growth brought on by periods of abundant rain and high temperatures, especially following periods of stress. It is common during rainy season when temperature is high, especially when rain follows long dry spell. Cracks of varying depth radiate from the stem end of the fruit, blemishing the fruit and providing entry for decay causing organisms. Radial cracking is more likely to develop in full ripe fruit than in mature green ones. Fruits exposed to sun develop more concentric cracking than those, which are covered with foliage.
Depending on the variety, fruits become ready for first picking in about 60-70 days after transplanting. The harvesting stage depends upon the purpose to which the fruits are to be used. The different harvesting stages are:
Mature dark green
Dark green colour is changed and a reddish pink shade is observed on fruit. Fruits to be shipped are harvested at this stage and are then sprayed with ethylene 48 hours prior to shipping. However, immature green tomatoes will ripen poorly and be of low quality. A simple way to determine maturity is to slice the tomato with a sharp knife. If seeds are cut, the fruit is too immature for harvest.
Pink colour observed on ¾ part of the fruit.
Fruits are stiff and nearly whole fruit turns reddish pink. Fruits for local sale are harvested at this stage.
Fully ripe stage
Fruits are fully ripened and soft having dark red colour. Such fruits are used for processing.
Over mature stage
Early morning or evening hours are best suited for harvest. Fruits are harvested by twisting motion of hand to separate fruits from the stem. Harvested fruits should be kept only in basket or crates and keep it in shade. Since all the fruits do not mature at the same time, they are harvested at an interval of 4 days. Generally there will be 7-11 harvests in a crop life span.
The yield per hectare varies greatly according to variety and season. On an average, the yield varies from 20-25 t/ha. Hybrid varieties may yield up to 50-60 t/ha.
Generally, tomatoes are picked in the green stage before becoming fully ripe for longer shelf life. The enzymes responsible for ripening stop working when temperature falls below 12.5 °C and therefore, when unripe tomatoes are kept in cold storage, it will not continue to ripen; and only fully ripe tomatoes can be stored in the refrigerator. The fruits are ripened in storage using ethylene gas. Fruits ripened in this way tend to keep longer but have poorer flavour and texture than tomatoes ripened on the plant, which can be recognized by their more pink or orange colour, from the normally ripened tomatoes, which are deep red in colour.
However, genetically modified tomato called the ‘Flavr Savr’, which could be vine ripened without compromising shelf life and "tomatoes on the vine", which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine and hence possessing more flavour than artificially ripened tomatoes are developed.
Another problem is that mature green tomato fruit is chilling sensitive and should not be stored at temperatures below 10°C. As the tomato fruit ripens it becomes less susceptible to chilling injury. At the pink stage tomatoes can be held at 5°C for 4 days without injury. When returned to 13 to 15°C pink fruit will complete ripening in 1 to 4 days.
Tomato is very popular as a salad vegetable and is processed into juice, canned tomatoes, soups, and tomato pastes. Other major culinary uses of tomatoes include tomato pickles, tomato purée, tomato pie, ketchup, pizza, and tomato sauce. It is the most widely used canned vegetable. Tomato juice is often canned and sold as a beverage. Tomato seed oil is extracted from waste seed of canning processes. Consumption of tomatoes is reported to benefit the heart. An antibiotic, tomatine, is also extracted from the seed. Lycopene, one of nature's most powerful antioxidants, is present in tomatoes and has been found to be beneficial in preventing prostate cancer, among other things. Tomato fruit is rich in vitamins A and C, calcium and potassium. The nutritional profile of tomato is as follows:
Mineral matter (0.6%)
P (44 mg/100g)
Ca (39 mg/100g)
Mg (31 mg/100g)
Fe (0.8 mg/100g)
Cu (0.02 mg/100g)
Leaves and stems contain toxic glycoalkoloids like solanine and demissine, which are poisonous and when ingested in large quantities can cause headache, abdominal pain, dilated pupils, vomiting, diarrhea, circulatory and respiratory depression, loss of sensation, etc.