1. Geographical Distribution in Africa
2.General Information and Agronomic Aspects
3.Fresh Quality Specifications for the Market in Kenya
4.Information on Pests and Weeds
5.Information on Pests
6.Information on Diseases
7. Information on Weeds
8.Information Source Links
9.Contact Information
Fruit on plant. Although tomatoes generally rank low in comparative nutritional value, they outrank all other vegetables in total contribution to human nutrition because so much is consumed in so many different ways.
Ⓒ Simone Hunziker
Anthracnose (Colletotrichum coccodes) on tomato
Ⓒ Clemson University - USDA Cooperative Extension Slide Series, www.insectimages.org (www.ecoport.org)
Spider mites on tomato. Note the mites and their webbing visible beetween the leaves.
Ⓒ Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Bacterial spot (Xanthomonas vesicatoria) on tomato fruit: Typical sunken, black spots on the fruit and malformation due to the bacterial infection.
Ⓒ Courtesy EcoPort (http://www.ecoport.org): Plant Protection Service Archives, Wageningen, NL
Damage of Bacterial spot (Xanthomonas campestris pv. vesicatoria) on tomato leaf.
Ⓒ Clemson University, www.insectimages.org
Bacterial speck (Pseudomonas syringae pv. tomato) of tomato seedlings. Note the necrotic lesions and the widespread chlorosis.
Ⓒ Courtesy EcoPort (http://www.ecoport.org): M.D. Laing
Tomato spotted wilt tospovirus: mottle in tomato fruit.
Ⓒ Courtesy EcoPort (http://www.ecoport.org): Mike Pearson
Damage on tomato fruit and leaves caused by the Tomato russet mite, Aculops lycopersici
Ⓒ Courtesy EcoPort (http://www.ecoport.org): L. Steynberg
Damage of bacterial wilt on tomato.
Ⓒ David B. Langston, University of Georgia, Bugwood.org
Blossom-end rot on tomato. Blackened or rotten appearance on the blossom end of the fruit caused by calcium deficiency and affects all fruiting vegetables. Secondary fungal infections may occur on the affected areas.
Powdery mildew (here on tomato)
Ⓒ A. A. Seif, icipe
Tomato mosaic virus
Ⓒ A.A. Seif, icipe
Early blight symptoms on tomato fruit
Ⓒ A.A.Seif, icipe
'Birds eye' symptoms on tomato caused by bacterial canker
Lycopersicon esculentum
Order / Family:
Solanales: Solanaceae
Local Names:
Nyanya (Swahili)
Pests & Diseases:
Fruit borers (Helicoverpa armiguera, Spodoptera littoralis)
Fruit borers such as the African bollworm (Helicoverpa armigera) and leaf-eating caterpillars such as the cotton leafworm (Spodoptera littoralis) attack the developing and mature fruit of tomato. The African bollworm, also known as the tomato fruit worm, is one of the most destructive insect pests of tomato, causing yield losses as high as 70% due to fruit boring. They usually bore into the fruit from the stem end, and feed on the inner parts of the fruits, causing extensive fruit damage and promoting decay caused by secondary infections.
They prefer green fruit. Caterpillar of the cotton leaf worm feeds on the leaves of tomato and bores into the fruit, especially those growing down the plant near to the soil. They are olive-green, dark grey or brown in colour with large, black, triangular spots on their back. The fully-grown caterpillars are 3 to 5 cm long. The eggs are laid in batches in one or more layers, usually on the underside of the leaves and covered with hairs. Both caterpillars have many natural enemies such as predatory ants, spiders, damsel and robber flies, and parasitic wasps and flies
The African bollworm or tomato fruitworm (Helicoverpa armiguera feeding on tomato fruit
(c) A. M. Varela, icipe
African bollworm (Helicoverpa armigera) damage on tomato
Ⓒ Anne Bruntse
The fruit borer or cotton leafworm (Spodoptera littoralis) feeding on tomato fruit.
Avoid planting tomato near maize or cotton to prevent heavy pest infestations.
Monitor the crop regularly. Detection of eggs and small caterpillars before they enter into the fruit is very important. Once the caterpillars have entered the fruit they are protected from insecticidal sprays and will have caused damage. Check also for natural enemies and parasitised eggs. Healthy eggs are white with a reddish ring, but they turn black when parasitised. It has been recommended to randomly select 30 tomato plants and examine the leaves immediately below the topmost open flowers to look for eggs of African bollworm (AVRDC, 2000).
Conserve natural enemies. A very rich variety of natural enemies of fruit borers have been recorded. The most important are parasitic wasps (egg and larval parasitoids) and predators such as anthocorid bugs, ants, lacewings and ladybird beetles. Although these natural enemies cannot always prevent economic damage, they play a significant role in controlling the pest populations. For more information on natural enemies click here.
Spray selective biopesticides such as Bt or neem extracts. Pyrethrin and rotenone are also used for control of this pest, but they are harmful to natural enemies and not allowed in organic agriculture. Control measures should start when more than five healthy eggs are found or when large numbers of small caterpillars are found on leaves. For more information on Neem click here. For information on Bt click here.
Hand pick and destroy eggs and caterpillars. This helps when their numbers are low and in small fields.
Anthracnose (Colletotrichum coccodes)
Spots of fruits are sunken. When weather is moist, the spots get tan-coloured (growth of fungal spores). There may be several spots on affected fruit and they may join up and cover the whole fruit. Severely affected fruits drop. Eventually, affected fruits dry and become black. Most often, soft-rot bacteria invade affected fruits and cause a soft watery decay.
The fungus usually attacks fruits on plants that are weakened or over-ripe. Infection is favoured by relative humidity close to 100% and temperatures between 21 and 300C.
Use resistant varieties, if available.
Use certified disease-free seeds.
Practise crop rotation.
Destroy infected crop residues.
Aphids (Aphis gossypii, Myzus persicae)
Aphids such as cotton aphid (Aphis gossypii) and the green peach aphid (Myzus persicae) suck plant sap, which can reduce plant growth; they also secrete honeydew, on which sooty moulds growth. Sooty mould on fruits reduces their market value. These aphids may also transmit virus diseases during feeding such as the cucumber mosaic virus. In Kenya, aphids are occasionally found on tomatoes, but they are not considered an important pest.
Green peach aphid (Myzus persicae) . Adult wingless females are 1.2-2.1 mm in body length and very variable in colour.
Ⓒ Whitney Cranshaw, Colorado State University, Bugwood.org
Conserve natural enemies. Aphids are usually kept under control by a wide range of natural enemies. For more information on Natural enemies click here
In particular, avoid use of wide spectrum pesticides since they kill natural enemies.
Use reflective mulch. Reflective aluminium mulches deter aphids from landing on plants. The effect is lost once plants are large enough to cover the mulch.
Use biopesticides that are not harmful to natural enemies (e.g. neem, ashes, soapy water). For more information on Biopesticides click here
Bacterial canker
Bacterial canker (Clavibacter michiganensis subsp. michiganensis)
The first symptoms are yellowing, curling and wilting of the leaflets, often on one side of the leaf. The affected leaflets turn brown and dry but remain attached to the plant. The whole plant may also show a one-sided disease development. Long brown strips may appear on stems and shoots. These strips dry and crack open to form cankers from which the disease gets its name. When an affected stem is cut lengthwise, there is a creamy white, yellow or reddish-brown line inside the woody tissue. The pith is easily separated from the wood along this line.
The vascular bundles within the pith are destroyed and cavities are formed in the pith. Young affected fruits are small, deformed and seeds are aborted. Also spots may develop on older fruits. These spots are circular, up to three mm wide, with slightly raised brown centre surrounded by a pronounced white halo resembling a 'bird's eye". The halo is flat. The bacterium is seed-borne and can survive up to three years in soil in crop debris. Spread within a crop is by rain splash, sprinklers and pruning knives.
Birds eye symptoms on tomato caused by bacterial canker
(c) A.A. Seif, icipe
Plant tolerant or resistant varieties, if available.
Rotate seedbeds and tomato fields with non-solanaceous crops.
Eradicate solanaceous weeds.
Avoid sprinkler irrigation where the disease is endemic.
Avoid working in tomato fields when it is wet.
Disinfect pruning knives with commercial detergents between plants .
Bacterial spot
Bacterial spot (Xanthomonas campestris pv. vesicatoria)
It is another serious disease, occurring during the rainy season. It is most noticeable on fruits, but also causes damage to the foliage and stems. On green fruits, the initial spot is very small and water soaked. It eventually enlarges to about 6 mm. As the bacterial spot matures, it becomes brown and scabby without extending deep into the fruit. On foliage, irregular greasy, dark green spots, 2 to 3 mm wide, are observed. The spots eventually dry and the tissue often tears. The disease is transmitted through the seed.
Bacterial spot (Xanthomonas vesicatoria) on tomato. Older spots are blackish and slighly raised, central spots disintegrate and sink
(c) A.M. Varela, A.A. Seif, icipe
Use certified disease-free seed.
Remove and destroy crop residues after harvest.
Avoid working in the fields when plants are wet.
Spray with copper fungicides; copper can control this disease fairly well except under heavy infection.
Grow resistant cultivars; this is the best control method for both bacterial diseases, but resistance is not universal owing to variable strains of the pathogens.
Bacterial wilt (Ralstonia solanacearum)
Bacterial wilt has often been reported as the most serious handicap for tomato in the tropics. The disease causes rapid wilting and death of the entire plant without any yellowing or spotting of leaves. Total collapse of the plant usually occurring when temperatures reach 320C and above. Plant wilts while still green. When the stem of a wilting plant is cut across, the pith has a darkened water-soaked appearance, and on squeezing the cut stem, a white, yellow or greyish, slimy exudate may appear. In later stages of the disease, decay of the pith may cause extensive hollowing of the stem.
A row of tomatoes with individual plants infected with bacterial wilt (Ralstonia solanacearum). Note that the wilt often starts next to a trellising pole because the pathogen can overwinter on the pole. Tomatoes in South Africa are typically cultivated with wire trellising to hold up the plants.
(c) Courtesy of EcoPort, www.ecoport.org
Use resistant varieties (e.g. "Fortune Maker", "Kentom" and "Taiwan F1")
If only a few wilted plants are found, immediately remove them from the field.
Practise long-term crop rotation.
A method called "bio-fumigation" is under development from the Australian Center for International Agricultural Research for the reduction and long-term elimination of bacterial diseases from the soil by incorporating especially mustard or radish plants in large amounts into the soil immediately before planting tomatoes or potatoes. This practice is reported to reduce incidence of bacterial wilt by 50-70% in the Philippines (ACIAR 2005/6). For more information on Biofumigation click here.
Blossom-end rot
It is caused by calcium deficiency and irregular watering. The disease occurs at the blossom-end of the fruit. It starts as a water-soaked spot that enlarges to become dark brown and sunken. The surface of the spot becomes dark and leathery. The rot is dry.
Stages of blossom-end rot
Avoid water stress during early stages of fruit development.
Apply lime in calcium deficient soils.
Apply foliar sprays of calcium chloride.
Cabbage looper (Trichoplusia ni)
In addition to the cotton leaf worm (see fruit borers), other caterpillars such as the cabbage looper (Trichoplusia ni) feed on tomato leaves. However, generally they are not of economic importance.
The cabbage looper is a green caterpillar with faint white stripes along the body. Caterpillars are about 3.5 to 4 cm long when fully-grown. As they move, they arch their back in a looping fashion, hence the common name looper. Larvae (caterpillars) chew holes in the leaves, and larger caterpillars consume great amounts of plant material.
The adult is a moth, about 2.5 cm in length and mottled, greyish-brown.
Cabbage looper on cabbage. The first instar is white and almost clear with a black head capsule. Later instars are green with a thin white line on each side. Mature larvae reach 3 to 4 cm in length.
Ⓒ A.M. Varela, icipe
Cabbage looper (adult moth). The adult is ca 2.5 cm in length and mottled, grayish-brown. The wingspan is ca. 4 cm.
Ⓒ Joseph Berger, www.insectimages.org. Courtesy of Ecoport (www.ecoport.org)
Conserve natural enemies. These caterpillars are attacked by a large numbers of natural enemies, including parasitic wasps and flies. Birds and bats feed on the adults (moths).
Pick caterpillars by hand and destroy them.
When control is necessary use biopesticides such as neem-based products or Bt. Neem products control cabbage looper by interfering with the growth of the young caterpillar. Bt and neem should be applied when caterpillars (larvae) are still in the early growth stages.
For more information on Neem click here.
For more information on Bt click here.
Cutworms (Agrotis spp)
Cutworms are the caterpillars of certain moths. They are serious pests of tomato seedlings. They cut stems of newly transplanted or emerged plants at the base. Cutworm damage is more critical after thinning or transplanting.
Cutworms Agrotis spp on tomato. Note cut seedling. Early instars are about 7 to 12 mm long. Fully grown caterpillars are 35 to 50 mm long.
A. M. Varela, icipe
Eliminate weeds early, at least 2 weeks before transplanting.
Plough and harrow the field prior to transplanting. This exposes cutworms to natural enemies and desiccation and helps destroy plant residue that could harbour cutworms.
Make barriers to protect the transplanted seedlings. Barriers can be made by wrapping paper, aluminium foil, thin cardboard or similar materials around the base of transplant stems. Toilet rolls are handy as cutworm collars since they are readily available and will biodegrade into the soil.
Dig near damaged seedlings and destroy cutworms.
Conserve natural enemies. Parasitic wasps and ants are important in natural control of cutworms.
Damping-off diseases (Pythium spp. and Rhizoctonia solani)
Damping-off can occur when seedlings die before they have pushed through the soil, resulting in patches that appear to have germinated poorly. Alternatively, seedlings may emerge but fall over and die some time afterwards. The base of stem of affected seedlings become wet and brown. These disease-causing fungi are common in moist soils. They can also be transmitted on seeds.
Tomato nursery damping-off
Ⓒ A.A. Seif
Tomato Rhizoctonia stem rot
(c) A.A. Seif
Use certified disease-free seeds. If it is farmer-saved seed, it can be given hot water treatment. For more information on Hot water treatment click here.
Do not site seedbed on a field previously planted with brinjals (eggplants), pepper, potatoes or tomatoes.
Solarisation of seedbed should be done where feasible. For more information on Solarisation click here .
Avoid excessive watering.
Early blight (Alternaria solani)
Leaf spots of early blight are circular, up to 12 mm in diameter, brown, and often show a circular pattern, which distinguishes this disease from other leaf spots on tomato.
Early blight (here on tomato leaf). Leaf spots of early blight are circular, up to 1 cm in diameter, brown, and often show a circular pattern, which distinguishes this disease from other leaf spots on tomato.
(c) A.M. Varela & A.A.Seif, icipe
Tomato early blight internal symptoms. Infected fruit on left with blackish pith
Tomato early blight stem lesion. Note characteristics rings on the spot
Use resistant varieties (e.g. "Rio Grande").
Use certified disease-free seeds. If using own seeds, hot water treat the seeds. For more information on Hot water treatment click here
Use disease-free plants.
Do not plant plant consecutively tomato crops on the same land.
Practise rotation with non-solanaceous crops (e.g. brassicas, legumes, small grains).
Stake and prune indeterminate varieties.
If disease is endemic, applied preventative sprays of copper compounds (e.g. copper hydroxide). For more information on Copper click here.
Fusarium wilt (Fusarium oxysporum sp. Lycopersici)
The lower leaves of the plant usually turn yellow and die. One or more branches may exhibit such symptoms. Leaflets on one side may be affected while those on the other side are symptomless. Diseased leaves readily break away from the stem. When affected stems just above ground level and petioles are cut diagonally, a reddish-brown discolouration of the water conducting tissues will be observed. The fungus is both seed- and soil-borne. It causes most damage on light, sandy soils. It is most active at temperatures between 25 and 320 C. The fungus can survive in the soil indefinitely even when no tomatoes are grown. It can also survive in fibrous roots of weeds (e.g. Amaranthus, Digitaria and Malva species). Acidic soils (pH 5.0 to 5.6) and excessive nitrogen fertilisation promote disease development. Infestation by root-knot nematodes encourages the disease.
Bacterial blight blackening of veins (here on okra)
(c) A.M. Varela & A.A. Seif, icipe
Tomato showing vascular wilt caused by Fusarium oxysporum f. sp. lycopersici (fungus).
(c) Scot Nelson, 2015
Use resistant tomato varieties (e.g. "Fortune Maker", "Rio Grande", "Tengeru 97", "Roma VFN").
Do not locate seedbeds on land where Fusarium wilt is known to have occurred.
Where soil is acidic, raise the pH by applying lime or farmyard manure.
Avoid excessive nitrogen fertilisation and control root-knot nematodes.
Late blight (Phytophthora infestans)
Symptoms of late blight are irregular, greenish-black, water soaked patches, which appear on the leaves. The spots soon turn brown and many of the affected leaves wither, yet frequently remain attached to the stem. Infection of the fruit occurs at any stage of growth. It is most common on the upper half of the fruit. The spots are greasy brown and have a firm corrugated (rough) surface that occasionally shows narrow zonate markings.
Late blight on tomatoes. Note scorched appearance of leaves, stems and fruits.
Ⓒ B. Loehr, icipe
Symptoms of late blight on tomato.
(c) B. Loehr, icipe
Use resistant varieties (e.g. "Rio Grande", "Tengeru 97" etc).
Use disease-free transplants.
Do not plant tomatoes after potatoes.
Leaf mould
Leaf mould (Mycovellosiella fulva)
Symptoms of leaf mould are pale-green or yellowish areas with undefined margins that appear on the upper leaf surface. Under humid conditions the lower leaf surfaces of the spots become covered by an olive-green to greyish-purple velvety growth of the fungus.
Tomato leaf mold symptoms
(c) Elizabeth Bush Virginia Polytechnic Institute and State University, 2013
Prune and stake to reduce humidity.
Avoid excessive shading by providing adequate plant and row spacing.
Avoid wetting leaves when watering.
Leafminers (Liriomyza spp.)
Leafmining flies make tiny punctures on the side of tomato leaves when feeding and laying eggs. These punctures may serve as entry point for disease causing organisms such as bacteria and fungi.
The most destructive stages are the immature stages (maggots). Maggots measure up to 3 mm in length. The maggots feed on leaf tissue inside the leaf leaving a wandering track in the form of irregular mines. Heavy mining of leaves may reduce photosynthesis affecting development of flowers and fruits. Heavy attack may cause leaf drop. This is particularly serious for tomato seedlings which may die due to defoliation. Defoliation of tomato plants may also expose fruits to sunburn and affect the market value. Leafminers attack a wide range of cultivated vegetables.
Damage by leafmining flies (Liriomyza spp.) on tomato leaf. Note maggot ready to pupate (yellow) and pupa (brown).
Ⓒ A. M. Varela, icipe
Conserve natural enemies. Parasitic wasps normally control leafminers. However, the widespread indiscriminate use of persistent broad-spectrum insecticides, to control this and other pests, disrupt the natural control, leading to leafminer outbreaks.
Rotate with non-host crops and plan the arrangement of fields so that old infested fields do not provide a reservoir of infestation for subsequent crops.
Destroy leafminer pupae in the soil. This can be done by ploughing and tilling, by solarisation, and, on heavy soils, by flood irrigation.
Monitor the crop by checking foliage for the presence of stipples caused by the adults while feeding and laying eggs, and for mines and larvae. Trap adult flies with yellow sticky or water traps. For more information on Traps click here.
If necessary spray with neem-based pesticides. For more information on Neem-based pesticides click here.
Powdery mildew (Leveillula taurica)
The spots of powdery mildew appear on older leaves and are light chlorotic to bright yellow. These spots later run together and become necrotic. Whole leaf blades may collapse and dry up. On the upper leaf surface of green leaves, a fine talcum-like powder is observed. This is fungal growth.
Powdery mildew on tomato
(c) A. A. Seif, icipe
Powdery mildew on sesame (Erysiphe cichoracearum)
(c) Courtesy EcoPort (http://www.ecoport.org): Jurgen Kranz
Keep tomato fields free of weeds.
Do not grow brinjals (eggplant) or tomatoes in succession.
Root-knot nematodes (Meloidogyne spp.)
Root-knot nematodes are very destructive to tomatoes. Damage is most serious on light sandy soils in furrow-irrigated crops. The nematodes cause small lumps known as root knots or galls on the roots. Heavily infected roots are severely distorted and swollen. In time the roots rot. The affected plants are either stunted or have tendency to wilt or even die in hot weather. The affected plants, in most cases, just wilt with the foliage still green - without yellowing. The nematode problem is primarily due to improper crop rotation.
Root-knot nematodes (Meloidogyne incognita / M. javanica) Roots of severely attacked (left) and healthy plant (right). Affected plants are normally stunted and eventually wilt and die. The most characteristic symptom is formation of root galls (knots) and these can be seen with the naked eye. Affected roots rot.
Rotate with tomato, brassicas or cereals.
Do not locate seedbeds where susceptible vegetables (e.g. okra, sweet pepper, eggplant, Irish potato, carrot or cucurbits) have been previously grown.
Use tolerant or resistant tomato varieties (e.g. "Roma VNF", "Shengena","Tengeru-97", "Kentom", "Caracas", "Carmello", "Diego", "Piersol" and "Vegas"). Varieties with the "VFN" label exhibit some resistance - the "N" stands for Nematode-tolerant.
Use mixed cropping or grow marigolds (Tagetes spp.) or sunnhemp (Crotalaria juncea).
Maintain high levels of organic matter in the soil (manure and compost).
Amend the soil with neem. Mixing neem cake (residue of neem seed after expression of neem oil) increases the organic content of the soil and kills nematodes due to the naturally-occurring nematicidal compounds in neem.
Spider mites (Tetranychus spp.)
Spider mites are important pests of tomatoes. They are more prevalent in dry areas. Infested leaves show a white to yellow speckling and then turn pale or bronzed. High spider mite infestation causes defoliation, which leads to production of smaller fruits with lower content of ascorbic acid (vitamin C). Spider mite feeding on fruits causes speckling of the fruits.
The tobacco spider mite Tetranychus evansi, is one of the most damaging spider mites on tomato. This spider mite can kill plants very rapidly under hot and dry conditions. Plants with high numbers of this mite can be covered with webbing and an orange cloud of mites.
Initial infestation of spider mites, note mites on underside of leaflet.
Tomato fruit damaged by spider mites
(c) A. M. Varela, icipe.
Severe spider mite damage to tomato plants.
Conserve natural enemies. Natural occurring predators are in many cases capable of controlling the two-spotted spider mite and the carmine red spider mite. However, this is not the case for the tobacco spider mite. There are few predators known to feed on this mite. In Kenya, ICIPE has released predatory mites for control of the tobacco spider mite in early 2007.
Inspect the crop regularly to determine the presence and level of infestation of spider mites. A recommended monitoring method is to select randomly 20 tomato plants and access the level of mite damage of three leaflets per plant using a leaf index ranking from 1 to 5 (1 is few yellow spots, 5 is leaf totally covered with spots, dry patches occur). Once the average damage level excess the first rank, control measures should start.
When detected early, initial infestations are usually concentrated on a few plants, in many cases in the borders of the field. In this situation, remove and burn or bury infested plants to prevent the problem from spreading and becoming serious.
Since mite populations are initially restricted to some plants, spot spraying (spraying only attacked plants) is usually effective.
Avoid the use of broad-spectrum insecticides. They may kill natural enemies. In addition some synthetic pyrethroids can actually enhance spider mite reproduction leading to mite outbreaks. Spraying neem extracts, soapy solutions and water are reported to help control red spider mites. For more information on Spider mites click here.
Avoid water stress. If necessary, irrigate the crop regularly, and apply mulch to reduce water evaporation
Practise good field sanitation to minimise the risk of infestation. Keep the field free from weeds, remove and burn or compost crop residues immediately after harvest.
Avoid planting new crops next to an already infested field (tomato or other crops).
Thrips (Thrips tabaci, Frankliniella occidentalis, F. schultzeii and Ceratothripoides brunneus)
Thrips may also be a problem in tomatoes in Kenya. Thrips are small (about 1 to 2 mm long). They usually feed on the lower surface of leaves puncturing them and suck the exuding sap. They also attack buds, flowers and fruits. Attacked leaves have a silvery sheen and show small black spots (thrips excrements). Under heavy infestation attacked buds, and flowers usually fall off. Attacked fruits show speckling and small necrotic patches on the surface affecting fruit quality. Fruits may become deformed.
Thrips feed on tomatoes at all stages, but their feeding on seedlings is particularly damaging. Heavy infestation can reduce stands of young seedlings in hot weather. Thrips of the genus Thrips and Frankliniella are vectors of viruses such as the Tomato Spotted Wilt Virus (the most economically important virus in tomato production) and the Tomato Chlorotic Spot Virus.
Thrips damage on tomato. Thrips are small (about 1 to 2 mm long)
Thrips damage to flower buds on tomato
Ⓒ A.M.Varela, icipe
Thrips damage to tomato leaflet
Thrips damage to tomato
#9400 A.A. Seif
Conserve natural enemies. Predatory mites (eg. Amblyseius sp.), anthocorid bugs (e.g. Orius spp.), and other predators such as ladybird beetles, lacewings and spiders, and the fungus Entomophthora are important in natural control of thrips.
Monitor the crop regularly. Check plants daily in the nursery, and crop borders in the field. Be particularly vigilant at flowering. Pay careful attention to flowers and flower buds.
Destroy thrips pupae in the soil. This helps reducing subsequent thrips populations. Plough and harrow before transplanting to expose pupae in the soil from previously infested crops to natural enemies and desiccation. Soil solarisation and flood irrigation (flooding previously infested fields prior to planting/transplanting) destroy a large proportion of thrips pupae present in the soil. For more information on Solarisation click here.
If necessary spray biopesticides. Neem and some other plant extracts are reported to control thrips. Spinosad, a bacterial derivative is effective in thrips control. However, timing of biopesticide application is important. Thrips are difficult to control with insecticides due to their secretive habits (eggs are laid in plant tissue, the larvae and adult shelter in the flowers and larvae pupate in the soil). Spraying early in the morning or in the evening and mixing the spray with a sugar solution (which attracts the thrips out of the flowers) are reported to increase efficacy of sprays.
Tomato mirid bug
Tomato mirid bug (Nesidiocoris tenuis)
It is slender, greenish in colour with a dark brown tint on the forewings. Eggs are laid singly on the growing points, petioles and stems of the tomato plant. The young bugs (nymphs) resemble the adults, but initially have no wings. Older nymphs have wing pads. The tomato bug feed on stems, leaves and flowers of tomatoes, but prefer young leaves and growing points. Sucking by nymphs and adults results in the formation of brownish rings on stems, petioles, growing points and leaf veins, which become brittle. Repeated feeding by the bugs cause crinkling (rolling, puckering and unevenness) of leaves.
Attacked stem bases become swollen with narrow brownish rings at the apices of the swollen areas. Shedding of flowers may be partly due to feeding by this bug. Other major crops attacked include eggplant, sesame and bottle gourds. The tomato bug also exhibits predatory habits, and has been reported preying on other insect pests, such as aphids, jassids (leafhoppers), caterpillars and whiteflies. It has been identified as an important predator of eggs and young caterpillars of the African bollworm and a potential control agent of whiteflies in Europe. This bug was found frequently and in large numbers on tomatoes, throughout NE and NW Somalia (Seif et al. 2003). It has also been reported as a tomato pest in Ghana (Youdeowei, 2002). In Kenya, large numbers of this bug have been observed in tomato fields under heavy and frequent spraying of synthetic pyrethroids.
Tomato bug adult (Nesidiocoris tenuis) on tomato plant, they are about 4mm long
Inspect crops for nymphs and adults feeding on buds, developing flowers and leaves, and for signs of bug feeding, including discoloured spots, necrosis, stunting, and early fall of flowers and fruits.
Avoid volunteer crops.
Assure proper disposal of crop residues.
Avoid indiscriminate use of broad-spectrum pesticides
Affected plants show light and dark green mottling and distortion of the youngest leaves. The latter may be stunted or elongated resembling fern leaves. Under high temperature and light intensity, mottling can be severe. Under low temperature and low light intensity, stunting and leaf distortion are severe. Internal browning of the fruit sometimes occurs; this symptom is most common when fruits become infected at mature green or pink stage.
The disease can be seed-borne but can also survive on plant debris in the soil and so re-infect newly planted crops. The virus is easily mechanically transmissible by contact between plants or through human activities (transplanting seedlings or pruning).
Tomaco mosaic virus. Note internal browing of the fruit.
(c) A. A. Seif and A. M. Varela, icipe
Use resistant varieties (e.g. "Alboran", "Kentom", "Meru", "Shengena", "Tengeru 97")
Avoid an overlap of tomato crops.
Do not use freshly harvested seeds.
Remove crop refuse and roots from fields.
Eradicate weeds.
Workers should not smoke or take snuff when working in tomato fields since the virus can be transmitted from tobacco.
Tomato russet mite
Tomato russet mite (Aculops lycopersici)
They are very tiny, approximately 0.2 mm long, and cannot be seen with the naked eye. They are yellowish, brown or pink. They have a ringed conical body with the head and two pairs of legs at the large end. They complete the lifecycle in 1 week; this explains the rapid increase of this mite in tomato fields. They prefer high temperatures and low humidity. They feed on all above-ground parts of the tomato plant, causing spotting, twisting or folding of leaves and fine cracks on the fruits. Attacked leaves and stems develop a greasy appearance and turn bronzed. The plants can drop their leaves, especially in hot weather. Fruits are then exposed to sunburn. Damage to the plant typically begins near the ground and spreads upwards. Damage can develop very rapidly, and the mites can kill plants in a few days in dry hot weather. Since the mite cannot be seen, the symptoms are easily confused with diseases. The small size of the mites makes monitoring difficult. The first signs of mite presence are the curling and bronzing of the lower leaves of the stem.
Conserve natural enemies. Few natural enemies of the tomato russet mite are known. Predatory mites are considered to be the most important natural enemies. However, the effect of these natural enemies is hampered by extensive use of pesticides.
Spray neem extracts. Neem oil and aqueous neem kernel have been reported to give good control of this mite in Costa Rica. For more information on Neem extracts click here.
Ensure proper irrigation during early stages of the crop. This can help prevent mite build-up later in the growing season since tomato russet mite infestation is higher on tomato plants under water stress.
No resistant varieties are available. In Kenya, tolerance to leaf damage was observed in two varieties, namely "Early Stone" and "Beauty".
Tomato spotted wilt virus
The virus is transmitted by thrips (Thrips tabaci and Frankliniella spp.). The virus has a wide host range including many ornamental plants, vegetable crops and weeds. Diseased leaves have purplish-brown spots. Diseased leaves later turn brown, die and droop. Brown streaks occur on leaf petioles and stems. Infected plant becomes dwarfed, and with its drooping leaves, it resembles a plant affected by wilt. Symptoms on fruits consist of circular zones with shades of yellow or brown alternating with green and later with pink or red. Fruit symptoms are very characteristic of the disease.
Plant resistant cultivars, (e.g. "Star 9006", "Star 9008")
Control the insect vectors early.
Practise general field sanitation.
Tomato yellow leaf curl virus
The virus is transmitted by Whiteflies (Bemisia tabaci). It is not seed-borne. Tomato plants infected early in the season are normally stunted and excessively branched. Affected leaves are chlorotic and are curled upward. Flower drop is common, and therefore, infected plants have a reduced number of flowers and fruits.
Tomato yellow leaf curl virus. Note thickened shoots.
Use resistant or tolerant varieties such as "Tengeru 97", "Amareto", "Peto 86", "Fiona F1", "Perlina", "Denise", "Cheyenne" ("E448"), "Rover", "Roma" and "Marglobe" is highly susceptible and should not be used in areas where the disease is common.
Protect seedbeds with a white nylon net (40 mesh), as the later the plants are infected with the virus the less impact the disease will have on yield reductions.
Rogue out diseased plants (in the seedbed and in the field) and destroy them.
Plant barrier crops.
Avoid continuous growing of tomato.
Control whiteflies. For more information on Whitefly control click here
Tuta absoluta (tomato leaf miner)
Tuta absoluta is a new insect pest of tomato plant in sub Saharan Africa. The moth pest originated from Peru and has spread to Europe, Africa and Asia. In Africa, T. absoluta was detected in Tunisia (2009), Ethiopia (2012), Senegal (2013), Sudan (2010) , Tanzania and Kenya (2014) and in Uganda (2015). Although tomato plant is the main host for T. absoluta, the pest also attacks other plants in the Solanacea family including potato, nightshade, eggplant, pepino, tobacco and solanaceous weeds such as Datura.
The life cycle of T. absoluta is completed within 30-35 days. T. absoluta can have 10-12 generations per year. Females can lay up 250-300 eggs on host plants. Eggs are small, cylindrical, creamy-white to yellow and approximately 0.35 mm long. Eggs hatch in 4-6 days after egg laying. The larva is cream-colored with a characteristic dark head. T. absoluta has four larval instars. Pupation may take place in the soil, on the leaf surface or within mines. The adults are small moths with 5-7 mm body length. The adults have thread-like antennae and forewings with grey scales and black spots.
The larvae feed between the leaf layers causing irregular mines. They eventually tunnel into the stems or burrow into the fruits, leaving black frass as it tunnels.
T. absoluta is a very challenging pest to control because of its fast reproductive rate (10 -12 generations per year), short life cycle, nocturnal adults, and concealed larval stage inside the plant parts. It can cause up to 100% loss of tomato fruits if left uncontrolled.
Tuta absoluta adult
(c) Marja van der Straten, NVWA Plant Protection Service, Bugwood.org
Tomato leaf miner feeding
(c) Goldlocki, 2005
Remove alternate host plants such as Datura stramonium, volunteer potato, eggplant or tomato plants.
Remove and destroy all infested plants and fruits
Practice crop rotation and intercropping
Mass trapping of leaf miner by using pheromone traps
Bio-pesticides such as Bacillus thuringiensis and neem
Bio-control agents, especially parasitoids
Soil solarisation can provide control of many soil-borne diseases, nematodes, and weeds. Preventing weeds from producing seed helps reduce weed populations in subsequent crops; this also applies to areas adjacent to the cropped fields. A soil cap (5 to 10 cm mound of soil) over the seedline at planting can reduce the first flush of weeds competing with the crop seedlings. The cap is removed just after tomato seedlings germinate, but before rapid elongation of the hypocotyls. This mound also reduces soil moisture loss and emergence problems that result from soil crusting after periods of rainfall, and is formed by disks or other implements.
When tomato seedlings are about 10 cm tall, cultivation can create a dry layer of soil (dry mulch) on the seedline to prevent weed seeds from germinating and to smother small weeds that have already emerged. Flaming is also used for weed control in large-scale commercial tomato production.
Striga (Striga hermonthica) weeds in maize field.
(c) Courtesy EcoPort (http://www.ecoport.org): David C. Nowell
Crop rotation can effectively reduce difficult weed problems by altering the environmental conditions that favour a particular weed species or by permitting the use of alternative methods to control these weeds. Lucerne is a good choice for a rotational crop because its frequent cutting cycle reduces many weeds. Maize is also used in rotations with tomato as it is not a host to tomato diseases and weeds can be controlled in this crop.
Tobacco whitefly (Bemisia tabaci)
Tobacco whitefly is a serious pest of tomatoes. Whiteflies attack tomatoes from seedling to mature stage. They suck sap from the leaves, and may weaken the plants. Feeding of whiteflies cause yellowing of infested leaves. Immature stages (nymphs) produce honeydew on which sooty mould grows. Heavy honeydew or mould coating reduces plant growth and fruit quality.
The main damage caused by whiteflies is indirect as vectors of virus diseases. Bemisia tabaci transmits several virus diseases in tomato. In particular it is an efficient vector of the Tomato Yellow Leaf Curl Virus (TYLCV), a major disease in Kenya.
Small numbers of whiteflies do not cause major direct plant damage. However, even small numbers of whiteflies may need to be controlled in areas where TYLCV is common.
Whiteflies on chilli leaf. Adults are about 1mm long.
Ⓒ B. Nyambo, A. A. Seif, icipe
Tomato leaf infested by whiteflies
Time sowing and transplanting. If possible avoid the season when whiteflies are more likely to occur.
Use cover crops (forage, peanut, weeds) and inert covers (silver, yellow, and white/black plastic mulches). They have been shown to reduce whitefly damage in tomatoes. Whiteflies are attracted by the colour of the plastic mulch. The heat of the plastic kills the whiteflies. However, this is effective as long as the plants are young and do not cover the mulch. The protection can last for 10 to 20 days after transplanting and about 30 days after direct seeding. Take care to avoid sunscald when using plastic covers.
Prevent physical contact of the whiteflies with the plant; this can prevent the transmission of viral diseases. Cover tomato seedling nurseries with nylon nets or use tunnels for 3 to 5 weeks to protect seedlings from whiteflies infestation. These methods have been reported to reduce the transmission of the Tomato Yellow Leaf Curl Virus in several countries.
Conserve natural enemies. Whiteflies are mainly attacked by parasitic wasps and by predators such as phytoseiid mites, lacewings and ladybird beetles. For more information on Natural enemies click here
Check the crop regularly. Use yellow sticky traps to monitor the presence of whitefly adults. Yellow traps are also an effective control method of whitefly at low infestations. For more information on Traps click here
Remove weeds in advance of planting tomatoes, and keep tomato fields weed-free. Weeds play an important role in harbouring whiteflies between crop plantings. They also often harbour whitefly-transmitted viruses.
If necessary spray neem extracts. Neem-based insecticides are reported to substantially reduce egg laying by B. tabaci, inhibit the growth and development of nymphs, and significantly reduce the risk of TYLCV transmission.
Spraying with soap and water solutions reportedly controls whiteflies. The amount of soap needed depends upon the soap type. For more information on Soap spray click here
Plant barrier crops. Fenugreek and coriander are reported to repel whiteflies.
Other pests: Armyworm, Broomrape, Black speck, Dodder, Sedges
Geographical Distribution in Africa
Geographical distribution of Tomato in Africa. Updated on 4 July 2019. Source FAOSTAT
General Information and Agronomic Aspects
Tomatoes are native to South and Central America, and are now cultivated widely throughout the world.
Tomatoes are one of the most widely cultivated vegetable crops in Africa. They are grown for home consumption in the backyard of almost every homestead across sub-Saharan Africa. They are important source of vitamins and an important cash crop for both smallholders and medium-scale commercial farmers. Tomatoes acting as taste enhancers in food are always in high demand both for fresh consumption and processing.
Tomato yields in smallholder cropping systems in the region are generally far below the potential of the crop. Average yields as low as 7 tons/ha have been reported from Tanzania and 10 tons/ha from Uganda, while yields as high as 100 tons/ha have been recorded from commercial farmers in Zimbabwe. There are several reasons for low yields. Among these are low quality seeds, non-availability of inputs, sub-optimum crop husbandry and a large number of pests and diseases.
Cherry Tomatoes are a fast expanding export crop in Kenya. These are miniature tomatoes with a preferred size of around 15 g per fruit. Cherry tomatoes are easier to grow organically than most other tomatoes as many of them have a high tolerance to diseases and can be grown successfully both under green house and open field conditions.
Nutritive Value per 100 g of edible Portion
Raw or Cooked Tomato Food
(Calories / %Daily Value*) Carbohydrates
(g / %DV) Fat
(g / %DV) Protein
(g / %DV) Calcium
(g / %DV) Phosphorus
(mg / %DV) Iron
(mg / %DV) Potassium
(mg / %DV) Vitamin A
(I.U) Vitamin C
(I.U) Vitamin B 6
(I.U) Vitamin B 12
(I.U) Thiamine
(mg / %DV) Riboflavin
(mg / %DV) Ash
(g / %DV)
Red Tomato cooked 18.0 / 1% 4.0 / 1% 0.1 / 5% 0.9 / 2% 11.0 / 1% 28.0 / 3% 0.7 / 4% 218.0 / 6% 489 IU / 10% 22.8 / 38% 0.1 / 4% 0.0 / 0% 0.0 / 2% 0.0 / 1% 0.6
Green Tomato raw 23.0 / 1% 5.1 / 2% 0.2 / 0% 1.2 / 2% 13.0 / 1% 28.0 / 3% 0.5 / 3% 204 / 6% 642 IU / 13% 23.4 / 39% 0.1 / 4% 0.0 / 0% 0.1 / 4% 0.0 / 2% 0.5
Orange Tomato raw 16.0 / 1% 3.2 / 1% 0.2 / 0% 1.2 / 2% 5.0 / 1% 29.0 / 3% 0.5 / 3% 212 / 6% 1496 IU / 30% 16.0 / 27% 0.1 / 3% 0.0 / 0% 0.0 / 3% 0.0 / 2% 0.7
Yellow Tomato raw 15.0 / 1% 3.0 / 1% 0.3 / 0% 1.0 / 2% 11.0 / 1% 36.0 / 4% 0.5 / 3% 258.0 / 7% 0.0 IU / 0% 9.0 / 15% 0.1 / 3% 0.0 / 0% 0.0 / 3% 0.0 / 3% 0.5
*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs.
Climate conditions, soil and water management
Ideally, tomato requires a relatively cool, dry climate for high yield and premium quality. However, it is adapted to a wide range of climatic conditions. Tomatoes have been grown as far north as the Arctic Circle (under protection) and down to the hot and humid equator. The optimum temperature range for growth and development is 21 to 24degC. Prolonged exposure to temperatures below 12degC can cause chilling injury. Mean temperatures above 27degC severely impair growth and fruit set. Destruction of pollen and egg cells occurs when the maximum day-time temperature is 38degC or above for 5 to 10 days. Fruit set is also generally poor if the night temperatures are above 21degC just before and after flower formation. Hot dry winds can also cause flower abortion. Tomatoes are not sensitive to day length and set fruits in photoperiods ranging from 7 to 19 hours. Tomatoes can be grown in many soil types ranging from sandy loam to clay-loam soils that are rich in organic matter. The ideal soil pH range is 6 to 6.5; higher or lower pH can cause mineral deficiencies or toxicities. Long periods of flooding are detrimental to tomato growth and development.
Small-holder farmer tomato seed production
For own seed production it is not recommended to use hybrid varieties. These varieties carry a label "F1". However, if a hybrid variety is preferred, it cannot be used for more than one generation (one crop cycle).
Conditions to be followed when producing seed:
The tomato seed should be multiplied only once.
Buffer zone for tomato seed plot should be 25 m from any other tomato crop.
The plot should not previously have had tomatoes planted recently.
The tomato crop should be scouted regularly for pests and diseases.
The first step fruits should not be included for seed extraction.
After planting the seed the off types should be uprooted early as when seen.
Weeding of plot should be properly done.
Proper crop management is needed i.e. fertiliser application, pruning, staking irrigation etc.
Seed extraction process
Pick ripe fruit at second cluster from only robust, disease-free plants (plants not infected with diseases: bacterial canker / bacterial speck / bacterial spot / anthracnose fruit rot / early blight / late blight / tomato mosaic virus).
Wash the fruit, preferably with a soap (potassium based) to decrease the chance of infection by diseases.
Cut the fruit in two pieces and remove the seeds with a spoon. Or the pieces can be squeezed out into a clean bucket, plastic, glass or ceramic bowl until only the seed-jelly and fruit sap is left.
Cover the bowl with cloth or paper to keep away dirt and other possible contaminants but do not make it airtight.
Let the seeds stand for 1 to 5 days (usually 2 to 3 days in warm areas).
Tomato seed extraction by smallholder farmers
Locally produced tomato seed
Stir the seeds daily to ensure uniform fermentation and to prevent seed discolouration.
Wash the fermented seeds in clean water. Any seeds that float during washing should be discarded because they are either not fully ripened or filled properly.
Dry the seeds in indirect light and in well-ventilated places. The seeds could be spread out over a clean manila sack to dry.
In case seeds cannot be sown immediately, they should be stored in a waterproof container (transparent plastic bag / non-coloured glass bottle). Transparent materials allow sunlight, which reduces mould development. Place a bit of ashes in the bottom of the container to absorb any moisture and to prevent the seeds from moulding. In case where pots or bottles are used for seed storage, the tops should be covered with plastic film to stop possible water seepage and mite infestation.
Store seed container in a cool place, as dry as possible.
Check the seeds regularly (at least weekly) for mould development. If mould is detected, dry the seeds again.
Seeds can be stored, if properly dried, up to 2 years.
One kg of tomatoes will produce between 1 and 4 grams of seeds.
(This information is based on a Biovision Project carried out in Taita Hills, Kenya, under Eastern Arc Mountains in conjunction with Wild Life Services)
Storage of locally produced tomato seeds in plastic bag
Propagation and planting
Tomatoes can be direct-seeded or transplanted in the field, but this method is expensive as large amounts of seed are required (about 500 to 1000 g of seeds/ ha) and adds about four weeks of weeding labour to growing costs. In contrast, raising the young transplants in a special nursery enables growers to achieve great seedling uniformity, requires smaller quantity of seed and saves on weeding costs.
Nursery bed preparation:
Construct raised seedbeds of maximum one m width in a place where no potatoes, tomatoes, eggplants or peppers have been grown for about 3 years.
Incorporate about 5 kg of good compost/ m2 into the seedbeds, which are finely cultivated on top.
Drill shallow seeding furrows with a pointed stick. One ha of tomatoes requires 150 to 200 g of well germinating seed.
Sow seeds in the furrows and cover them lightly with soil.
Pat firmly with the flat side of a rake or similar tool, mulch and water liberally.
Never use fresh manure on a seed bed as it will burn young seedlings.
After emergence of seedlings push away the mulch from the rows to allow sunlight to get through to the young seedlings.
Individual plant raising in banana leaf pots or plastic seedling trays will greatly improve eventual plant establishment, by reducing transplanting shock and root damage during transplanting.
The young seedlings require sufficient water to sustain good, healthy growth.A week before transplanting, reduce watering to harden the seedlings. Three- to four-week-old seedlings (15 to 25 cm high with 3 to 5 true leaves) are ready for transplanting. Seedlings must be thoroughly watered 12 to 14 hours before they are lifted out of the seedbed, to avoid excessive damage to the roots. Transplant seedlings in the afternoon or on a still, cloudy day to reduce the transplanting shock, and water them immediately. As little as a cup of water per plant immediately at planting will greatly speed up plant establishment.
Spacing between plants and distance between rows depends on the cultivar's growth habit and whether the plants are to be supported by stakes or left to grow on the ground.
Indeterminate varieties are generally staked while determinate varieties can be grown in the field without staking. Common configurations are plants spaced 30 to 60 cm apart in single or double rows on 1.0 to 1.4 m wide beds.
Common Varieties available in Kenya and their yield potential
Table: Common tomatoe varieties available in Kenya and their yield potential
Varieties for processing
Yield potential (tonnes/ha)
"Roma VF"
"Sun Marzano"
"Rutgers 10x Hybrid"
"Heinz 1350"
"Roma Nova"
"Cal J"
"M-82" 57
"Riogrande" 49
Varieties for Fresh Market
"Prostar F1"
"Money Maker"
"Early Beauty"
"Super Marmande"
"Ponderosa"
"Hot Set"
"Best of all"
"Marglobe"
"BWN 21"
"Kenton F1"
"Zawadi"
"New Fortune Maker"
Table: Some varieties reported to be tolerant (T) or resistant (R) to pests and diseases available in East, Central and Southern Africa
Variety Bacterial wilt Early blight Fusarium and Verticilium wilt Late blight Red spider mites Root-knot nematodes Tomato Mosaic Virus Tomato Yellow Leaf Curl Virus
"Alboran" - - - T - - - -
"Fortune Maker" R - R - - - - -
"Kentom" R - - - - R R -
"Meru" - - - R - - R -
"Rio Grande" - R R R - - - -
"Roma VF" - - R - - - - -
"Roma VFN" - - R - R R - -
"Shengena" - - - R - R R -
"Taiwan F1" R - - - - - - -
"Tengeru 97" - - R R - R R R
The breeding of tropical cherry tomato lines has been done by World Vegetable Centre in Taiwan. All varieties available in Kenya so far are indeterminate and take 65 to 72 days to yield from date of transplanting. Cherry Tomatoes can typically produce for longer seasons than ordinary tomatoes due to their disease resistance or tolerance. The cultivars "Sugar Pearl" and "Girls Sweet" produce fruit that are prone to fruit cracking, so preferred varieties include "Tiny Tim", "Super Sweet 100F1", "Cherry King F1", "Cherry Sweet 100F1", "Sweetie" etc. Note that varieties with the added F1 on their name are hybrids, and seed collection from these may not produce as well as the bought seed. However "Tiny Tim" and "Sweetie" are open pollinated, and farmers could propagate seed from the best plants with good results.
Tomatoes respond very well to liberal amounts of well-rotted compost or manure. In addition a spoonful (or 3 teaspoons) of rock phosphate should be added to each planting hole. If the soil is poor in organic matter it is advisable to grow a crop of good quality green manure such as cowpeas, mucuna, soybean, or crotalaria before transplanting tomato seedlings. Avoid commercial nitrogen fertilisers as excess nitrogen is associated with fruit puffiness and blossom-end rot, and generally causes excessive vegetative growth. Excess free nitrogen in the soil also causes softer leaves and makes the plants attractive to pests and diseases. Competition with weeds, especially in the hot and humid tropics, can be very severe. To control weeds on open land crops, slash regularly emerging weeds as close to the ground as possible between rows of tomatoes is recommended. Leave slashed weeds on the soil as mulch to help prevent erosion, reduce soil temperature and conserve soil moisture. This should be supplemented by manual weeding in rows and mulching the beds with straw.
For tall growing indeterminate varieties, put a 2 m stake firmly in the ground for each tomato plant and tie the stems loosely as the plant grows. Alternatively put a stout pole in the ground at every four m and two wires run - 1 at 2 m and another one at 0,15 m above the ground. Tye a fairly strong string between the two wires behind each tomato plant. The plants can then be carefully twisted around the strings as they grow.
Pruning of tomato plants is necessary for indeterminate varieties. One or two main stems should be allowed to grow and the side branches (laterals) pinched off as the crop grown on a weekly basis. When 6 to 8 flower clusters are formed, the growing top should be pinched off to encourage the growth of good size marketable fruit. Leaves close to the ground should be removed to help prevent entry of blight infection. No pruning and regulation of fruit number and clusters are normally practised on determinate cultivars. Semi-determinate cultivars may be grown either as a determinate or indeterminate crop. Smokers should wash their hands carefully with soap before handling tomato plants as they may otherwise transmit tobacco mosaic virus disease.
Tomatoes need adequate irrigation during the early plant growth, fruit set and fruit enlargement stages. Consistency of water supply to the plants plays a major role in attaining uniform maturity. It also reduces the incidence of blossom-end rot, a physiological disorder normally attributed to calcium deficiency during fruit enlargement. In dry weather watering is essential at least two times a week. Drip irrigation is the most efficient and risk free method of irrigation, as it does not create water splashes onto the plants.
Cherry tomatoes although indeterminate can produce quite well even when not staked in the field, but must then be given adequate space as they spread quite extensively ( one m2 per plant is minimum). Higher production and easier field management are benefits of the expensive staking procedure.
Fresh-market tomatoes are often harvested at the mature-green stage and ripened in transit or in storage before they are marketed. Ethylene is sometimes used to rapidly and uniformly ripen mature-green tomatoes prior to shipping them to the market, but this adversely affects quality. This is not a common practice in Kenya. Generally, tomatoes harvested at pre-ripe stages tend to be of lower quality (lower soluble solids, ascorbic acid and reducing sugars) than plant-ripened tomatoes. The nature of the growth and ripening pattern of fresh-market tomato cultivars require frequent pickings for either mature-green or plant-ripe fruits. In contrast to the fresh-market or table tomatoes, processing tomatoes are picked fully ripe. In developed countries, harvesting is often by machine. Tomatoes used for pureed products such as soup, juice and sauces, are left on the plant until over 85% of the fruits are ripe. Those for whole tomatoes are picked while still firm, but often only 65% of the crop may be ready to be picked all at once.
After picking, tomatoes should be stored in a shady place either in the field or at home to prepare them for the market. Properly sorted and graded fruits generally command a better market price than ungraded fruits. The marketable fruits are then packaged in suitable containers, often 20-kg wooden boxes, bamboo baskets, plastic boxes, or other locally available packaging materials. Proper packaging protects fruits from injury and reduces water loss. The storage life of tomatoes depends on the maturity stage at which they are harvested and on the desired quality of fruits. Quality is highest when completely ripe, whether artificially or on the plant. Ideally mature-green tomatoes should be stored for 7 to 10 days at 13 to 18degC at 85 to 90% RH so that they will ripen properly. Colour is the single most important visual parameter of tomato quality. Lycopene development at temperatures above 30degC is generally poor. This is the main reason that tomatoes grown in the hot tropics tend to have a pale red or yellowish colour and are poorly flavoured.
Harvesting and packaging of cherry tomatoes depend on market requirements. For distant markets, the fruit clusters may be cut when the fruits start turning to a red or pink colour depending on the cultivar. Firm red ripe fruits are required for the domestic market. However for the export market, cherry tomatoes are graded and packaged into pre-packs before shipment direct to supermarkets in the export destinations. On the whole a marketable yield of 20 tons /ha and above is considered a good yield. Yield of up to 60 tons/ha have been obtained under experimental conditions at KALRO,Thika Horticultural Research Station.
Fresh Quality Specifications for the Market in Kenya
The following specifications constitute raw material purchasing requirements.
Fresh quality specifications for cherry tomatoes
(c) S. Kahumbu, Kenya
Information on Pests and Weeds
The main tomato pests in east and southern Africa are red spider mites and russet mites, fruitworms, whiteflies, leafminers and thrips.
Examples of Tomato Pests and Organic Control Methods
Information on Pests
More information on Cutworms
More information on Aphids
More information on Root-knot nematodes
More information on Whiteflies
More information on Thrips
More information on Leafmining flies (leafminers)
More information on African bollworm
More information on Spider mites
More information on Cabbage looper
Information on Diseases
The main diseases affecting tomatoes in the region are early blight, late blight, bacterial wilt, Fusarium wilt, bacterial canker and root-knot nematodes.
Other bacterial diseases of tomato include bacterial speck (Pseudomonas syringae pv. tomato), bacterial stem and fruit rot (Erwinia carotovora subsp. carotovora), and pith necrosis (Pseudomonas corrugata).
Other important fungal diseases of tomatoes are leaf mould (Mycovellosiella fulva) and powdery mildew (Leveillula taurica).
Recent surveys have shown that viral diseases are a major constraint to tomato production in Eastern and Southern Africa. Important virus diseases are Tomato yellow leaf curl virus, and more recently also Tomato spotted wilt virus.
More information on Anthracnose
More information on Bacterial wilt
More information on Powdery mildew
More information on Tomato Yellow Leaf Curl Virus Disease (TYLCV)
More information on Damping-off diseases
More information on Fusarium wilt
More information on Early blight
More information on Late blight
Information on Weeds
More information on Weeds
Information Source Links
ACIAR, "Partners in Research for Development" Magazine, Summer 2005/6. www.aciar.gov.au
AIC (2000). Local and Export Vegetables Growing Manual. Nairobi Kenya
AIC (2003). Fruits and Vegetables Technical Handbook. Nairobi, Kenya
AVRDC. Tomato fruitworm. www.avrdc.org
CAB International (2005). Crop Protection Compendium, 2005 Edition. Wallingford, UK www.cabi.org
Dobson, H, Cooper, J., Manyangarirwa, W.,Karuma, J. and Chiimba, W. (2002). Integrated Vegetable Pest Management - Safe and sustainable protection of small-scale brassicas and tomatoes. Natural Resources Institute, University of Greenwich, UK ISBN: 0-85954-536-9
East African Seed Co. Ltd. Africa's Best Grower's Guide www.easeed.com
Nutrition Data www.nutritiondata.com.
Seif, A. A., Varela, A. M. and Nyambo, B. (2003). Tomato pests and diseases in Somalia and their control. Edited by A. J. Harberd. Integrated Pest Management Project in Somalia. UNA IPM Project.
Varela, A.M., Seif, A.A. and Loehr, L. (2003). A Guide to IPM in Tomato Production in Eastern and Southern Africa. ICIPE, Kenya. ISBN: 92 9064 149 5.
Youdeowei, A. (2002). Integrated pest management practices for the production of vegetables. GTZ. Integrated Pest Management Extension Guide 4. Published by The Ministry of Food and Agriculture (MOFA) Plant Protection and Regulatory Services Directorate (PPRSD), Ghana with the German Development Cooperation (GTZ). ISBN: 9988-0-1088-5.
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