Eggplant (Under development)

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Scientific Name
Solanum melongena
Order / Family
Solanales: Solanaceae
Local Names
Aubergine, Brinjal, Birigiyani (Swahili)
Pests & Diseases:
Anthracnose

Anthracnose (Colletotrichum melongenae)

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 30°C.
  • Anthracnose symptoms on eggplant

    Anthracnose symptoms on eggplant, following artificial inoculation via needle puncture of fruit.

    © Anna L. Snowdon. Reproduced from the Crop Protection Compendium. CAB International, Wallingford, UK, 2004.
What to do:
  • Use resistant varieties, if available.
  • Use certified disease-free seeds.
  • Practise crop rotation.
  • Destroy infected crop residues.
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Aphids

Aphids (Aphis gossypii)

Aphids are found in groups on the under surface of young leaves. When numbers increase they can move to upper leaf surfaces, stems and flowers. Aphids, in particular the cotton aphid, can become important pests in the cool dry season.

 

  • The cotton aphid (Aphis gossypii) is a small aphid. Adults range from just under 1-1.5 mm in body length.

    © Mississippi State University Archive, Mississippi State University, Bugwood.org
What to do:
  • Spray neem products. They have a repellent effect and have been effective in reducing numbers of the cotton aphid on eggplants. Effective treatments included foliar sprays with aqueous extracts of neem seeds, kernel and neem cake at concentrations of 10 to 50 g/l, and 3% neem oil applied at 10 days intervals. Bare root dipping with 50g/l aqueous neem kernel seed extract, 3% neem oil and a 10 g/l aqueous neem cake extract have also been effective (Ostermann & Dreyer,1995).
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Bacterial wilt

Bacterial wilt (Ralstonia solanacearum)

This disease occurs with bad drainage, especially in the hot, wet season and is often combined with symptoms of root-knot nematodes. Plants wilt and die suddenly. When newly infected stems are cut crosswise and placed in water, a greyish or yellowish ooze appears from the cut stem. The pathogen is soil-borne with a wide host range. Root-knot nematode infestation aggravates the disease development.


 

  • Bacterial wilt symptoms on potato plants. The first visible symptom on foliage is a wilting of the leaves at the ends of the branches during the heat of the day with recovery at night. As the disease develops, a streaky brown discoloration of the stem may be observed on stems 2.5 cm or more above the soil line, and the leaves develop a bronze tint.

    â’¸ A.A. Seif, icipe
What to do:
  • Use resistant varieties, if available.
  • Use certified disease-free seeds.
  • Remove infected plants from fields and destroy affected plants.
  • Rotate with non-solanaceous crops (e.g. maize or beans).
  • Use raised beds for improved drainage.
  • Graft plants onto resistant rootstocks.
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Budworm

Budworm (Scrobipalpa blapsigona)

It is reported as one of the major pests of eggplants in Ghana. The small brown caterpillars of the budworm bore into flower buds and feed inside the flowers. This causes the flowers to drop off. Budworm damage is often overlooked, but it can be serious, leading to very low fruit set (Youdeowi, 2002).

 

  • Parasitic wasp emerged from caterpillar. Note emergence hole in mummified caterpillar.

    (c) A. M. Varela.
What to do:
  • Conserve natural enemies. Caterpillars are usually parasitised by wasps.
  • Practise crop rotation.
  • Avoid growing eggplant two years in succession.
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Cotton leafhoppers or jassids

Cotton leafhoppers or jassids

They are small insects (1-3 mm long), green in colour with slender tapered bodies. Leafhoppers are very mobile. The adults hop away when disturbed. Nymphs resemble adults, but have no wings, and run sideways when disturbed. The eggs are inserted in the leaf tissue on the underside of leaflets. They feed mainly on the underside of eggplant leaves, causing small yellow patches on leaves. Infested leaves curl upwards along the margin. Under heavy attack, leaves turn yellow and then brown and dry, giving a burned appearance. Fruit setting may be very low. Leafhoppers multiply rapidly during dry spells and can cause extensive damage.

 

  • Leafhopper. Adults are small, about 2.5 mm long. Picture shows Empoasca fabae

    â’¸ Steve L. Brown, University of Georgia, Bugwood.org
What to do:
  • Spray neem products. Commercial and simple (home-made) neem products give control of leafhoppers on eggplants. Thus, an aqueous neem seed extract (10g/l) sprayed at 10 days interval showed repellent effects against leafhoppers (Empoasca) in India. Weekly applications of aqueous neem kernel extracts (6 to 50g/l) and of neem oil (5 to 10 l/ha) controlled the leafhopper, Jacobiasca facialis, in Togo (Osterman and Dreyer, 1995). In Sudan, the commercial products (Neem-Azal-T/S and neem oil-Rimulgan), and home-made neem products (50g/l) controlled leafhoppers on potatoes and eggplants.Control was improved when the neem extract was applied with a pre-pressurised knap sack sprayer instead of a palm leaf brush (El Shafie, 2001).
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Cutworms

Cutworms (Agrotis spp.)

These caterpillars are serious pests particularly in nurseries and of newly transplanted plants. They attack eggplants and many other plants at night. They cut seedlings and usually drag them down into the soil leaving the clean-cut stem. They cannot cut older plants. Large ground beetles, frogs, and birds prey cutworm.

 

  • Cutworm (Agrotis sp.) Early instars are about 7-12 mm long. Fully grown caterpillars are 35-50 mm long.

    â’¸ A.M. Varela, icipe
What to do:
  • 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.
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Early blight

Early blight or Alternaria leaf and fruit spots (Alternaria spp.)

Several Alternaria spp. are involved. These include A. melongenae, A. solani and A. tenuis. They cause leaf spotting and fruit rots. They produce leaf spots with concentric rings. The spots are mostly irregular, 4 to 8 mm in diameter and may enlarge and cover a large area of the leaf blade. Severely infected leaves drop off prematurely resulting in the reduction of yield. Fruit spots are circular, brown, dry and hard.

 

  • 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.

    © A.M. Varela & A.A.Seif, icipe
What to do:
  • Observe proper field sanitation.
  • Use certified disease-free seed.
  • Own seed should be water heat treated. For more information on Hot water treatment click here.
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Eggplant lace bug

Eggplant lace bug (Urentius hystricellus)

It is a small bug (about 3 mm in length), brownish in colour. Its body is covered with spines and the wings show a distinct lace-like appearance. Nymphs resemble adults, but are initially wingless, developing wings as they grow. Both adults and nymphs are usually found in groups on the underside of leaves. They suck sap from the leaves causing whitish to yellowish mottled patches on the leaves. In case of serious infestations the leaves turn entirely yellow and drop off. Attacked leaves are speckled with small black shiny spots, which are the faeces of the bugs.

 

  • Close-up of an adult of the eggplant lace bug (Urentius hystricellus). Real size: 3 mm in length.

    © M. Billah, icipe
What to do:
  • Spray neem products. They have given effective control of lace bugs on eggplants. The lace bug (Urenthius sp.) was repelled from eggplant plots treated with neem oil (5, 10 and 20%). However, concentrations of 10 and 20% showed phytotoxic effects.

    Weekly sprays of an aqueous neem seed extract (50 g/l) and 2% neem oil gave good results against another species of lace bug (Corythaica cyathicollis) attacking eggplant in the Caribbean (Ostermann and Dreyer, 1995).
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Epilachna beetles

Epilachna beetles (Epilachna spp.)

The adult beetle is oval in shape, about 6 mm in length and reddish brown in colour with black spots on their backs. They look very similar to the beneficial ladybird beetles (predators), but the body of this pest ladybird beetle is covered with short, light coloured hairs, which give them a non-glossy or matt appearance. The larvae are pale yellow and covered with branched spines.

They feed on the leaves of eggplants by scraping the surface and eating the leaf tissue between the veins. Attacked leaves may be completely stripped to the mid-veins to skeletons. They may also feed on fruits causing small shallow hollows on the fruit surface. High numbers of these beetles can cause considerable damage.

 

  • Epilachna beetles (Epilachna spp.) larvae and pupae on eggplant. Larvae are about 6 mm long.

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org
What to do:
  • Hand pick and destroy adults and larvae. This is feasible in small plots.
  • Spray neem products. Neem extracts have repellent effects on these beetles. For instance, sprays with an aqueous neem seed extract (10g/l) at 10 days intervals showed repellent effect on Epilachna beetles in India (Ostermann and Dreyer, 1995).
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Fusarium wilt

Fusarium wilt (Fusarium oxysporum f.sp. melongenae)

Affected plants show yellowing of leaves that progressively wilt and die from bottom upwards. Woody stem and root tissue of diseased plants turn brown. This fungus does not affect tomatoes. Optimum temperature for its growth on eggplants is 27.8 °C.

 

  • Bacterial blight blackening of veins (here on okra)

    © A.M. Varela & A.A. Seif, icipe
What to do:
  • Use resistant varieties, if available
  • Amend soils with organic matter (e.g. compost)
  • Practice crop rotation
  • In some countries susceptible eggplant varieties are grafted onto resistant rootstocks (e.g. Solanum gilo and S. integrefolium).
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Late blight

Late blight (Phytophthora infestans)

The late blight fungus affects tomatos, potatoes and eggplants but not pepper. Its symptoms consist of brown spots with purplish tinge and they can develop on leaves, stems, branches and both green and ripe fruits. In moist weather it can cause complete defoliation and rotting of fruits.

 

  • Phytopthora infestans on potato tuber

    (c) Fry W, EcoPort

  • Phytophtora infestans on tomato

    (c) Laing MD, EcoPort
What to do:
  • Use resistant varieties, if available
  • Practise rotation with non-solanaceous crops (e.g. tomato, potato, peppers etc) for 3 to 4 years. However, this will only be effective if it is done in cooperation with neighbouring farmers since the fungal spores can travel quite large distances by wind.
  • In wet weather, copper fungicides, could be applied as soon as the disease is observed or as soon as local experience suggests that the weather conditions are favourable for disease development.
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Mole crickets

Mole crickets, Tobacco Cricket (Brachytrupes spp.)

Mole crickets are a local sporadic pest of many crops including tobacco, tomato, tea and cotton. They have been reported as major pests of eggplants in Ghana. seedlings are particularly vulnerable.

Mole crickets live in the soil, feeding on the roots of many vegetables, leaving the clean-cut stem. They leave their burrows at night to cut and forage for seedlings and drag them down into the soil or leave them wilting on the surface for a few days before being taken into the burrow. Their underground burrows reaching a depth of 60-80 cm. They prefer mainly sandy soils where the adults can easily burrow. 

The adult is fat and 5 cm long, the adult female will live 3-4 months and lay over 300 eggs. Male mole crickets sing by stridulating, always underground, to attract females.

 

  • Tobacco Cricket (Brachytrupes membranaceus)

    © Bernard Dupont, 2015, Wikipedia
What to do:
  • Hand pick adults from their burrows.
  • Sprinkle wood ash in nursery.
  • Plough deep to destroy burrows.
  • Expose insects to predators. Large ground beetles, frogs and birds prey on mole crickets.
  • A few 1-cm-wide openings may be found around the damaged plants. The mole crickets can be forced into the open and captured when water is poured into the burrows.
  • Sound trapping: accoustic traps caught an other cricket (Gryllotalpa africana / CABI) species so it it could be tried out.
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Phytophthora fruit rot

Phytophthora fruit rot (Phytophthora parasitica)

Phytophthora fruit rot fungus can cause damping-off in seedbeds, leaf spotting and collar rot on the main stem final resulting in plant death. The fungus may attack fruit at any growth stage and any part of the fruit. Spots on the fruit are dark brown, water-soaked and may have a light-coloured border. A whitish mould develops on the spots when wet conditions prevail. The spots are neither sunken nor exhibit concentric rings (zonation). Infected fruits drop prematurely.

 

The fungus is soil-borne. It is spread in the field by run-off water and farm implements. The disease is favoured by prolonged periods of high moisture and temperatures near 30° C.

 

  • Phytophthora_parasitica_host_symptoms

    (c) Supattra Intavimolsri Department of Agriculture, Thailand
What to do:
  • Avoid dense planting.
  • Remove and destroy diseased fruit and plants.
  • Plough deep because Phytophthora would not survive.
  • Practise crop rotation with non-solanaceous crops such as tomato, potato and peppers.
  • Where practical, add copper sulphate to irrigation water.
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Powdery mildew

Powdery mildew (Leveillula taurica)

Symptoms appear as yellowish spots on the leaves. On the lower surface of affected leaves the spots are covered by a whitish growth constituting spores of the fungus. Affected leaves eventually dry up but do not fall off. The fungus is endophytic (grows within the leaf contrary to other powdery mildew fungi that are grow on surface of the leaves). It has a wide host range. It is not seed-borne but it survives on herbaceous weeds and other susceptible hosts. Temperatures slightly above 20 degC, dry conditions and fairly high relative humidity favour disease infection. However, fungal dispersal takes place mainly at low humidity.

 

  • Powdery mildew (here on tomato)

    â’¸ A. A. Seif, icipe
What to do:
  • Use of resistant varieties, if available.
  • Use overhead irrigation.
  • Use sulphur sprays.
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Root-knot nematodes

Root-knot nematodes (Meloidogyne spp.)

Eggplant is highly susceptible to root-knot nematodes, especially on sandy soils. Symptoms of infestation by root-knot nematodes are similar in all crops: wilting of plants and if infested plants are pulled from the soil the roots can be seen to be distorted, swollen and bearing knots. The infested roots eventually rot and affected plants die.

 

  • 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.

    © A. M. Varela, icipe
What to do:
  • Use resistant varieties, if available.
  • Practise crop rotation.
  • Practise mixed cropping. Mixed cropping with African marigold (Tagetes spp.) minimises root-knot nematode damage. Intercrop with different mustards (e.g. Brassica juncea var. integrifolia or Brassica juncea var. juncea) on infested fields. As soon as mustards are flowering they are mulched and incorporated into the soil. While incorporated plant parts are decomposing in a moist soil, nematicidal compounds of this decomposing process do kill nematodes. Two weeks after incorporating plant material into the soil a new crop can be planted or sown (phytotoxic effects are usual if the crop is planted before two weeks).
  • Use bioproducts (e.g. neem extracts). For more information on Neem click here.
  • Use biofumigation where possible.
  • Maintain high levels of organic matter in the soil (manure or compost).
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Shoot and fruit borer

Shoot and fruit borer (Leucinodes orbonalis)

It is a major pest of eggplant. The adult is a small moth, with a wingspan of 18-24 mm, white in colour with a pink and bluish tinge, and a few brown spots on its wings. Moths lay creamy white single eggs on leaf undersides, stems, flower buds, or the base of fruits. Upon hatching the caterpillars (white in colour) bore into the top section of fruits and tender shoots. Caterpillars develop inside fruits and stems reaching a length of 15-18 mm. When fully-grown, caterpillars make a small hole in the fruit or shoot and drop to the soil and pupate among fallen debris.

 

When plants start bearing fruits, most caterpillars prefer to feed on the tender fruits. The damage to the shoots is not seen until they droop as a result of the caterpillar feeding inside them. Recently damaged fruits are not easy to detect. The first indication of damage to the fruit is a small hole just below the calyx where the insect has entered. Fruits are filled with frass. They change colour and taste; they drop off and are unmarketable. Caterpillars are difficult to control with pesticides. Within hours of hatching from eggs, caterpillars enter the shoots or fruits, and are not reached by contact pesticides.

 

  • Eggplant fruit borer (Leucinodes orbonalis)

    © Koen V.N.Maes
What to do:
  • Conserve natural enemies. Predatory ants are the main natural enemies of the shoot and fruit borer. Other natural enemies include: ladybird beetles, praying mantis, earwigs, predatory bugs and spiders.
  • Destroy old eggplant plants and stubble (burn or bury them) immediately after harvest. Pupae can survive in the stubble for several weeks, infesting the new crop.
  • Use healthy, pest-free seedlings. Raise seedlings far away from sources of infestation (old eggplant fields, eggplant stubble)
  • Grow seedlings under nylon netting to prevent moths from laying eggs on the plants.
  • Remove and destroy infested shoots (readily visible as dry tip of branches). Burn, shred into tiny pieces or bury attacked shoots at least 20 cm in the soil. If this is done by all farmers in a community, especially before fruiting, pest infestation and damage can be drastically reduced. Continue cutting attacked shoots at least once a week until the final harvest.
  • Destroy infested fruits found during harvest.
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Spider mites

Spider mites (Tetranychus spp.)

Spider mites may become serious pests of eggplant during the dry season. Attacked leaves show a stippled appearance (white specks), and their surface covered with a fine web. Continuous infestation causes the leaves to dry-up. The plants are stunted and yields reduced.

 

  • A related Spider mites species on cotton leaf. They are very tiny (they rarely exceed a size of 0.5 mm)

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org
What to do:
  • Conserve natural enemies. Predatory mites and anthocorid bugs are important in natural control of mites.
  • Avoid use of broad-spectrum pesticides. They may kill natural enemies and may lead to mite outbreaks.
  • Provide good growing conditions for plants. Healthy plants are more likely to withstand mite attack. Adequate irrigation is particularly important. Apply mulch and incorporate organic matter into the soil to improve the water holding capacity and reduce evaporation.
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Thrips

Thrips (Thrips spp and Frankliniella spp.)

Thrips are small (1.5 mm long), slender, brown insects with pale yellow hind wings that appear as a yellow line down the back of the body when the insect is at rest. Adult thrips have characteristic wings; the transparent wings have a fringe of hairs around the outside edge standing out in the same plane as the wing.

 

Thrips attack eggplant mostly during the dry season. They cause browning of leaves, especially on the lower leaf surface. In severe cases, the entire leaf dries. Thrips feeding on fruits causesscarring, irregular discolouration and deformation, which reduce the market value of fruits.

 

  • Thrips damage on eggplant

    © A.M. Varela, icipe

  • Close-up of Thrips (Megalurothrips sjostedti (black) and Frankliniella occidentalis (yellow). Real size (0.9 to 1.1 mm)

    â’¸ GTZ-IPM Horticulture, Kenya
What to do:
  • Monitor the crop regularly for early detection of the pest and signs of infestation.
  • Conserve natural enemies. Anthocorid bugs and predatory mites are important natural enemies of thrips. Avoid use of pesticides that kill natural enemies.
  • Whenever necessary spray the crop with botanicals or other biopesticides. Some plant extracts (e.g. garlic, rotenone, neem, pyrethrum, and a mixture of garlic and pepper) are reported to control thrips. Spinosad, a bacterial derivative, is effective in controlling thrips.
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Weeds

Weeds

Eggplant is slow to become established and cannot compete with aggressive weeds. Weeds also harbour insect pests and diseases.

  • Striga (Striga hermonthica) weeds in maize field.

    © Courtesy EcoPort (http://www.ecoport.org): David C. Nowell
What to do:
  • Remove weeds by hand regularly.
  • Cultivate the land. Only shallow cultivation is necessary.
  • Mulch plants. Black plastic mulch effectively controls weeds and reduces labour needs. Natural organic mulches such as rice straw help conserving moisture and add organic matter to the soil.
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Whiteflies

Whiteflies (Bemisia tabaci)

Whiteflies feed on leaves of eggplant sucking plant sap. Whiteflies are vectors of the mosaic virus reported to occasionally affect eggplant in West Africa.

 

  • Adults and immature stages of the cabbage whitefly (Aleyrodes proletella).

    â’¸ A. M. Varela, icipe
What to do:
  • Apply neem products. Neem products have given control of the tobacco whitefly on eggplant. In the Caribbean, weekly sprays of neem seed powder (50g/l), and 2% neem oil gave good protection against this pest (Ostermann and Dreyer, 1995).

    In Sudan, commercial neem products and home-made products (neem seed water extract 50g/l) reduced the populations of Bemisia tabaci on eggplant and potato (El Shafie, 2001).
Other pests: Broomrape, Sedges, Snails

Geographical Distribution in Africa

Geographical Distribution of Eggplant in Africa. Updated on 8 July 2019. Source FAOSTAT

 

General Information and Agronomic Aspects

Introduction 

Solanum melongena, commonly known as eggplant or aubergine, belongs to the family Solanaceae and the genus Solanum. The Solanum genus consists of more than 1000 species and is widely distributed, with approximately 100 native African species. The genus Solanum includes many economically important plants, including tomatoes, potatoes, and eggplants. 
The exact origin of S. melongena is not entirely clear, but it is believed to be native to South Central China, Laos, Myanmar, Thailand, and Vietnam. Today, they are widely grown in many countries, especially in tropical and subtropical regions, where the climate is suitable for their growth..
Eggplants are widely utilized as a food source in many cuisines worldwide. Their versatile nature allows them to be prepared in various ways, including grilling, roasting, frying, and baking. They are used in a wide array of dishes, including curries, stews, salads, dips, and spreads. Eggplants are prized for their ability to absorb flavors from other ingredients, making them a popular addition to many cuisines around the world. The young and almost mature fruits are used as a vegetable. The fruit is a good source of vitamin A and C, potassium, phosphorous and calcium. They may be roasted, fried, stuffed, cooked as curry or pickled. Cooking for prolonged periods will destroy most of the vitamins. In Kenya production is done throughout the year and the bulk of the crop is exported. The fruits of the white varieties have medicinal value for diabetics. Eggplant has a cropping period of 4-7 months. In Kenya they are normally planted from beginning of June to end of December to correspond with the export season from October to May.
Eggplants are low in calories and fat but rich in dietary fiber, vitamins, and minerals. They are particularly abundant in antioxidants like anthocyanins, which give eggplants their characteristic purple color and have been associated with numerous health benefits. Beyond culinary uses, eggplants have also been utilized in traditional medicine in some cultures. They have been believed to have anti-inflammatory properties and have been used to treat various conditions, including digestive issues and skin problems. 
(Daunay, M. & Chadha, M., 2004, Lester, R.N. & Seck, A., 2004, Bukenya-Ziraba, R., 2004, Kew botanical gardens, North Carolina Extension Gardener (n,d)).

Species account

Solanum melongena is an annual herb to perennial shrub growing to a height of 150-200 cm, often much branched with a long taproot which extends deep into the ground. Its stems and leaves are densely covered with star-shaped (stellate) hairs and sometimes prickles. Leaves: alternate, simple, with a petiole (appendage which connects the blade to the stem) 6-10 cm long. Flowers: are hermaphrodite, generally smooth and shiny with many seeds. Fruits: Globular to ovoid, ellipsoid in shape and available in purple, green, white, and variegated colors. The deep purple eggplant has very high gloss. 
The fruit is consumed while still immature, displaying a glossy and vibrant appearance. However, once it reaches maturity, the flesh becomes bitter and fibrous, and the seeds harden. Certain cultivars are enjoyed raw.
(Plant village. (n.d), Daunay, M. & Chadha, M, 2004, Kew botanical gardens).

: Round brinjals in Nairobi market, Kenya â’¸ Food of the Nairobi people, 2005.

 

 White eggplants in Nairobi market, Kenya â’¸ Food of the Nairobi people, 2005.

Related species
Solanum aethiopicum commonly known as African eggplant, is native to Africa, domesticated from the wild Solanum anguivi Lam., via the semi-domesticated Solanum distichum Schumach. & Thonn. Over time, it has spread beyond its native lands and can now be found in different countries across Asia, Europe, and the Americas.
Solanum aethiopicum is a perennial herbaceous plant typically growing to a height of 1 to 2 m. Leaves: alternate and can vary in shape, from ovate to lanceolate, sometimes featuring lobes. Flowers: star-shaped flowers displaying color variation, from elegant white to captivating purple. Fruits: edible fruits, show diversity in shapes, sizes, and colors, including green, yellow, red, and purple. They find their place as a delightful vegetable in numerous culinary creations, such as stews, soups, and stir-fries, offering a unique flavor and texture to dishes.
The leaves, too, have their use as leafy vegetables in cooking and contribute valuable nutrients to diets. In traditional medicine, different parts of the plant have been employed to address various health issues, such as skin infections, stomach ailments, and respiratory problems 
Within Solanum aethiopicum, four cultivar-groups are recognized, three of which hold particular significance in Africa. 

Solanum aethiopicum, Vihiga, Kenya. ©Maundu 2021.

•    Gilo Group: The Gilo Group includes cultivars that are widely grown and valued for their large, round, and glossy fruits. Depending on the location, preferences vary for cultivars with pure white, creamy white, pale green, dark green, brown, or purple fruits, as well as striped fruits in two or more colors. These eggplants are highly versatile and used in various culinary dishes, providing a mild, pleasant taste. The Gilo Group is known for its adaptability to different environmental conditions, making it a popular choice among farmers and a preferred option for local markets and household consumption in Africa.
•    Shum Group are mainly known for its smooth mature leaves with tiny glandular hairs and non-prickly nature. The fruit is subglobose, about 1 to 3 cm in diameter. Primarily, it is used as a leafy vegetable, but ripe fruits are occasionally consumed too. This group is most prevalent in Central Africa, particularly popular in Cameroon and Nigeria. However, its popularity is even higher in Uganda, where it is locally called 'nakati.' It thrives in warm, high-rainfall areas or when grown under irrigation.
•    Kumba Group: mainly found in hot, semi-arid regions of the Sahel. Its mature leaves are smooth, except for tiny glandular hairs, and they are not prickly. The fruit is depressed globose, deeply furrowed, and often divided into many small vesicles, measuring 5-10(15) cm in width. Both the fruits and occasionally the leaves are consumed. Its importance for Africa is not as pronounced as the other three groups.
•    Aculeatum Group: have thorny stems and leaves with stellate hairs when mature. Its fruit is subglobose and furrowed, measuring 3–8 cm in diameter. While it is not consumed as food, it is grown for ornamental purposes or used as rootstock for tomatoes or eggplants. The cultivar is not cultivated in Africa.
(Lester, R.N. & Seck, A., 2004, Schippers, R. R, 2000)
 

Solanum aethiopicum plant in fruit, Vihiga, Kenya. © Maundu P, 2015.

Solanum anguivi is native to Africa, widely distributed on the African continent and its neighboring islands and Arabia. It has been recorded from West Africa, as well as Central Africa, East Africa, southern Africa and Madagascar, but it probably occurs in all non-arid regions throughout tropical Africa. It grows mostly in the wild, but sometimes, e.g. in Uganda and Côte d’Ivoire, it is a semi-cultivated vegetable.
S. anguivi is an upright woody herb or shrub, growing to a height of 4 m. Stems and leaves armed with straight or somewhat curved spines, yellowish to brownish, sometimes purple near the base, up to 13 mm long, branches often purple tinged. All parts covered in stellate hairs. Leaves: rhombic-ovate, elliptic or lanceolate, thinly stellate hairy above, densely so below. The central ray of the stellate hairs often much longer than the lateral rays. Leaf margin subentire to triangularly lobed. Prickles usually present on the midrib and main veins. Flowers; arranged in clusters of up to 20 blooms and have a pale mauve or purple color, with a star-like shape. Fruits: 6-12 mm in diameter, spherical, green, turning yellow and glossy orange-red when ripe. Edible when mature.
(Hyde, M.A., et al.,2023, Bukenya-Ziraba, R., 2004).

 

Nutritive Value per 100 g of edible Portion

Raw or Cooked Eggplant Food
Energy
(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)
Eggplant cooked 35.0 / 2% 8.7 / 3% 0.2 / 0% 0.8 / 2% 6.0 / 1% 15.0 / 1% 0.3 / 1% 123 / 4% 37.0 IU / 1% 1.3 / 2% 0.1 / 4% 0.0 / 0% 0.1 / 5% 0.0 / 1% 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

Optimum day temperatures for eggplant are in the range of 25-35°C and night temperatures from 20-27°C. Eggplant is more susceptible to low temperatures than tomato and capsicum and it does not tolerate frost. It is tolerant to drought and excessive rainfall, but struggles to grow when temperatures exceed 30°C, and where water logging occurs. When temperature and humidity are high, eggplant becomes more vegetative. Eggplant does best in well-drained, sandy loam soils. The best environmental conditions are normally found in lowland areas with relatively little temperature variation. When grown at altitudes above 800 m, growth is retarded and yields reduced. The pH requirements range from 6 to 7 with the optimum being pH 6.4. 
 

Propagation and planting

Eggplant is normally propagated by seed. Propagation by rooting of healthy shoots is also possible. Soaking the seeds in water for 24 hours speeds up germination. No treatment is needed when sowing fresh, vigorous seed in sterilised soil. Otherwise, soak seeds in warm water (50 °C) for 30 minutes, rinse them in cold water, and dry them before sowing. For information on hot-water treatment for seeds click here 

Nursery preparation

The seeds are sown in a well-prepared raised seedbed with friable soil (soil that breaks or crumbles easily when handled) in rows 10 cm apart. Space the seeds well to make transplanting easier. Before sowing an application of 3 to 5 kg of good compost per m² is incorporated into the nursery seedbed. 

In tropical areas, seeds are sown in a shaded seedbed and watered regularly. The seedlings emerge after 8-10 days. Before planting, fertilise the field with compost or farmyard manure. 
The ideal transplant is a seedling with three to four true leaves, stocky and disease-free, and without flower buds. Begin hardening plants 6 to 9 days before transplanting to reduce transplanting shock. Slightly withhold water. Thoroughly water seedlings 12 to 14 hours before transplanting to the field. Transplanting should be done in the late afternoon or on a cloudy day in order to minimise transplanting shock. Before transplanting, place a basal dose of 15 to 30 tons/ha compost or well-rotted farmyard manure in the planting furrows or planting holes and mixed with the soil. 
Transplant seedlings by digging a hole deep enough to bury a plant so that its first true leaf is just above the soil surface. Press the soil firmly around the root. Irrigate furrows immediately after transplanting. 
Watering newly transplanted plants well with compost tea or EM (effective microorganisms) will give the seedlings a good start. To prepare your own compost tea, mix 1 part of compost with 6 parts of water. Leave the mixture for one week. Strain and spray on seedlings to control fungal pathogens and prevent infection. 
 

Varieties

Seeds of the below listed varieties are commercially available in all seed companies in Kenya. Information on seed companies in Kenya can be obtained from Horticultural Crops Development Authority (md@hcda.or.ke www.hcda.or.ke +2542088469)
  • "Black Beauty" It takes about 100 days from transplanting to harvest. The fruit is oval to heart shaped glossy purple to almost black. Fruit size is about 10 x 8 cm. It has a good shelf life. It is unsuitable in cold wet areas.
  • "Florida High Bush" From transplanting to harvest is about 100 days. Fruit shape is elongate oval. Fruit size is about 15 x 8 cm. It is unsuitable for cold wet areas.
  • "Ravaya" It is an early maturing (about 80 days), high yielding variety. The fruits are slender, purple-coloured and borne in bunches of 3-4. This variety is popular for fresh export market.
  • "Long Purple". It is ready for harvest about 70-80 days after transplanting. Fruit shape is cylindrical. Fruit size is about 11 x 5 cm. It is unsuitable for cold wet areas
  • ."Early Long Purple". From transplanting to harvest is 90 days. Fruit shape is long cylindrical. Fruit size is about 12 x 6 cm. It is unsuitable to cold wet areas.

Crop rotation

Eggplants should not be planted after tomato, pepper, potato, or other solanaceous crops to prevent a recurrence of the same pests and disease pathogens. Rotate eggplants with other crops like onions, cereals or legumes. Planting eggplant after rice reduces the incidence of bacterial wilt and nematodes. 
 

Husbandry

Side dressing with groundnut cake is recommended 40 days after transplanting. Also at this period, remove three nodes at the tips of the plants to improve branching and to increase the number of fruits. Weed control should be shallow, to avoid damage to the roots. Tall-growing cultivars will also require support. Supplementary irrigation is required during dry periods. Mulching with dried plant materials reduces moisture loss and weed problems. Apply well-decomposed farm yard manure and neem cake as basal fertilisers.
 

Harvesting

The first harvestable fruits appear 60-90 days after planting. Harvest fruits when they are about two-thirds of their maximum size. Harvesting is done once or twice a week by cutting the fruit from the stem and leaving a short piece of stem on the fruit. For seed production, harvest only fully mature fruits from healthy and productive plants. Yields of 20 to 25 tons/ha of immature fruits can be expected.

 

Fresh Quality Specifications for the Market in Kenya

The following specifications constitute raw material purchasing requirements.

 

© S. Kahumbu, Kenya

Cutworms (Agrotis spp.)

These caterpillars are serious pests particularly in nurseries and of newly transplanted plants. They attack eggplants and many other plants at night. They cut seedlings and usually drag them down into the soil leaving the clean-cut stem. They cannot cut older plants. Large ground beetles, frogs, and birds prey cutworm.

 

What to do:
  • 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.

  • Cutworm (Agrotis sp.) Early instars are about 7-12 mm long. Fully grown caterpillars are 35-50 mm long.

    â’¸ A.M. Varela, icipe

  • Cutworm (Agrotis sp.) Early instars are about 7-12 mm long. Fully grown caterpillars are 35-50 mm long.

    â’¸ A.M. Varela, icipe

Budworm (Scrobipalpa blapsigona)

It is reported as one of the major pests of eggplants in Ghana. The small brown caterpillars of the budworm bore into flower buds and feed inside the flowers. This causes the flowers to drop off. Budworm damage is often overlooked, but it can be serious, leading to very low fruit set (Youdeowi, 2002).

 

What to do:
  • Conserve natural enemies. Caterpillars are usually parasitised by wasps.
  • Practise crop rotation.
  • Avoid growing eggplant two years in succession.

  • Parasitic wasp emerged from caterpillar. Note emergence hole in mummified caterpillar.

    (c) A. M. Varela.

  • Parasitic wasp emerged from caterpillar. Note emergence hole in mummified caterpillar.

    (c) A. M. Varela.

Whiteflies (Bemisia tabaci)

Whiteflies feed on leaves of eggplant sucking plant sap. Whiteflies are vectors of the mosaic virus reported to occasionally affect eggplant in West Africa.

 

What to do:
  • Apply neem products. Neem products have given control of the tobacco whitefly on eggplant. In the Caribbean, weekly sprays of neem seed powder (50g/l), and 2% neem oil gave good protection against this pest (Ostermann and Dreyer, 1995).

    In Sudan, commercial neem products and home-made products (neem seed water extract 50g/l) reduced the populations of Bemisia tabaci on eggplant and potato (El Shafie, 2001).

  • Adults and immature stages of the cabbage whitefly (Aleyrodes proletella).

    â’¸ A. M. Varela, icipe

  • Adults and immature stages of the cabbage whitefly (Aleyrodes proletella).

    â’¸ A. M. Varela, icipe

Root-knot nematodes (Meloidogyne spp.)

Eggplant is highly susceptible to root-knot nematodes, especially on sandy soils. Symptoms of infestation by root-knot nematodes are similar in all crops: wilting of plants and if infested plants are pulled from the soil the roots can be seen to be distorted, swollen and bearing knots. The infested roots eventually rot and affected plants die.

 

What to do:
  • Use resistant varieties, if available.
  • Practise crop rotation.
  • Practise mixed cropping. Mixed cropping with African marigold (Tagetes spp.) minimises root-knot nematode damage. Intercrop with different mustards (e.g. Brassica juncea var. integrifolia or Brassica juncea var. juncea) on infested fields. As soon as mustards are flowering they are mulched and incorporated into the soil. While incorporated plant parts are decomposing in a moist soil, nematicidal compounds of this decomposing process do kill nematodes. Two weeks after incorporating plant material into the soil a new crop can be planted or sown (phytotoxic effects are usual if the crop is planted before two weeks).
  • Use bioproducts (e.g. neem extracts). For more information on Neem click here.
  • Use biofumigation where possible.
  • Maintain high levels of organic matter in the soil (manure or compost).

  • 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.

    © A. M. Varela, icipe

  • 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.

    © A. M. Varela, icipe

Weeds

Eggplant is slow to become established and cannot compete with aggressive weeds. Weeds also harbour insect pests and diseases.

What to do:
  • Remove weeds by hand regularly.
  • Cultivate the land. Only shallow cultivation is necessary.
  • Mulch plants. Black plastic mulch effectively controls weeds and reduces labour needs. Natural organic mulches such as rice straw help conserving moisture and add organic matter to the soil.

  • Striga (Striga hermonthica) weeds in maize field.

    © Courtesy EcoPort (http://www.ecoport.org): David C. Nowell

  • Striga (Striga hermonthica) weeds in maize field.

    © Courtesy EcoPort (http://www.ecoport.org): David C. Nowell

Mole crickets, Tobacco Cricket (Brachytrupes spp.)

Mole crickets are a local sporadic pest of many crops including tobacco, tomato, tea and cotton. They have been reported as major pests of eggplants in Ghana. seedlings are particularly vulnerable.

Mole crickets live in the soil, feeding on the roots of many vegetables, leaving the clean-cut stem. They leave their burrows at night to cut and forage for seedlings and drag them down into the soil or leave them wilting on the surface for a few days before being taken into the burrow. Their underground burrows reaching a depth of 60-80 cm. They prefer mainly sandy soils where the adults can easily burrow. 

The adult is fat and 5 cm long, the adult female will live 3-4 months and lay over 300 eggs. Male mole crickets sing by stridulating, always underground, to attract females.

 

What to do:
  • Hand pick adults from their burrows.
  • Sprinkle wood ash in nursery.
  • Plough deep to destroy burrows.
  • Expose insects to predators. Large ground beetles, frogs and birds prey on mole crickets.
  • A few 1-cm-wide openings may be found around the damaged plants. The mole crickets can be forced into the open and captured when water is poured into the burrows.
  • Sound trapping: accoustic traps caught an other cricket (Gryllotalpa africana / CABI) species so it it could be tried out.

  • Tobacco Cricket (Brachytrupes membranaceus)

    © Bernard Dupont, 2015, Wikipedia

  • Tobacco Cricket (Brachytrupes membranaceus)

    © Bernard Dupont, 2015, Wikipedia

Thrips (Thrips spp and Frankliniella spp.)

Thrips are small (1.5 mm long), slender, brown insects with pale yellow hind wings that appear as a yellow line down the back of the body when the insect is at rest. Adult thrips have characteristic wings; the transparent wings have a fringe of hairs around the outside edge standing out in the same plane as the wing.

 

Thrips attack eggplant mostly during the dry season. They cause browning of leaves, especially on the lower leaf surface. In severe cases, the entire leaf dries. Thrips feeding on fruits causesscarring, irregular discolouration and deformation, which reduce the market value of fruits.

 

What to do:
  • Monitor the crop regularly for early detection of the pest and signs of infestation.
  • Conserve natural enemies. Anthocorid bugs and predatory mites are important natural enemies of thrips. Avoid use of pesticides that kill natural enemies.
  • Whenever necessary spray the crop with botanicals or other biopesticides. Some plant extracts (e.g. garlic, rotenone, neem, pyrethrum, and a mixture of garlic and pepper) are reported to control thrips. Spinosad, a bacterial derivative, is effective in controlling thrips.

  • Thrips damage on eggplant

    © A.M. Varela, icipe

  • Close-up of Thrips (Megalurothrips sjostedti (black) and Frankliniella occidentalis (yellow). Real size (0.9 to 1.1 mm)

    â’¸ GTZ-IPM Horticulture, Kenya

  • Thrips damage on eggplant

    © A.M. Varela, icipe

  • Close-up of Thrips (Megalurothrips sjostedti (black) and Frankliniella occidentalis (yellow). Real size (0.9 to 1.1 mm)

    â’¸ GTZ-IPM Horticulture, Kenya

Cotton leafhoppers or jassids

They are small insects (1-3 mm long), green in colour with slender tapered bodies. Leafhoppers are very mobile. The adults hop away when disturbed. Nymphs resemble adults, but have no wings, and run sideways when disturbed. The eggs are inserted in the leaf tissue on the underside of leaflets. They feed mainly on the underside of eggplant leaves, causing small yellow patches on leaves. Infested leaves curl upwards along the margin. Under heavy attack, leaves turn yellow and then brown and dry, giving a burned appearance. Fruit setting may be very low. Leafhoppers multiply rapidly during dry spells and can cause extensive damage.

 

What to do:
  • Spray neem products. Commercial and simple (home-made) neem products give control of leafhoppers on eggplants. Thus, an aqueous neem seed extract (10g/l) sprayed at 10 days interval showed repellent effects against leafhoppers (Empoasca) in India. Weekly applications of aqueous neem kernel extracts (6 to 50g/l) and of neem oil (5 to 10 l/ha) controlled the leafhopper, Jacobiasca facialis, in Togo (Osterman and Dreyer, 1995). In Sudan, the commercial products (Neem-Azal-T/S and neem oil-Rimulgan), and home-made neem products (50g/l) controlled leafhoppers on potatoes and eggplants.Control was improved when the neem extract was applied with a pre-pressurised knap sack sprayer instead of a palm leaf brush (El Shafie, 2001).

  • Leafhopper. Adults are small, about 2.5 mm long. Picture shows Empoasca fabae

    â’¸ Steve L. Brown, University of Georgia, Bugwood.org

  • Leafhopper. Adults are small, about 2.5 mm long. Picture shows Empoasca fabae

    â’¸ Steve L. Brown, University of Georgia, Bugwood.org

Aphids (Aphis gossypii)

Aphids are found in groups on the under surface of young leaves. When numbers increase they can move to upper leaf surfaces, stems and flowers. Aphids, in particular the cotton aphid, can become important pests in the cool dry season.

 

What to do:
  • Spray neem products. They have a repellent effect and have been effective in reducing numbers of the cotton aphid on eggplants. Effective treatments included foliar sprays with aqueous extracts of neem seeds, kernel and neem cake at concentrations of 10 to 50 g/l, and 3% neem oil applied at 10 days intervals. Bare root dipping with 50g/l aqueous neem kernel seed extract, 3% neem oil and a 10 g/l aqueous neem cake extract have also been effective (Ostermann & Dreyer,1995).

  • The cotton aphid (Aphis gossypii) is a small aphid. Adults range from just under 1-1.5 mm in body length.

    © Mississippi State University Archive, Mississippi State University, Bugwood.org

  • The cotton aphid (Aphis gossypii) is a small aphid. Adults range from just under 1-1.5 mm in body length.

    © Mississippi State University Archive, Mississippi State University, Bugwood.org

Spider mites (Tetranychus spp.)

Spider mites may become serious pests of eggplant during the dry season. Attacked leaves show a stippled appearance (white specks), and their surface covered with a fine web. Continuous infestation causes the leaves to dry-up. The plants are stunted and yields reduced.

 

What to do:
  • Conserve natural enemies. Predatory mites and anthocorid bugs are important in natural control of mites.
  • Avoid use of broad-spectrum pesticides. They may kill natural enemies and may lead to mite outbreaks.
  • Provide good growing conditions for plants. Healthy plants are more likely to withstand mite attack. Adequate irrigation is particularly important. Apply mulch and incorporate organic matter into the soil to improve the water holding capacity and reduce evaporation.

  • A related Spider mites species on cotton leaf. They are very tiny (they rarely exceed a size of 0.5 mm)

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org

  • A related Spider mites species on cotton leaf. They are very tiny (they rarely exceed a size of 0.5 mm)

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org

Epilachna beetles (Epilachna spp.)

The adult beetle is oval in shape, about 6 mm in length and reddish brown in colour with black spots on their backs. They look very similar to the beneficial ladybird beetles (predators), but the body of this pest ladybird beetle is covered with short, light coloured hairs, which give them a non-glossy or matt appearance. The larvae are pale yellow and covered with branched spines.

They feed on the leaves of eggplants by scraping the surface and eating the leaf tissue between the veins. Attacked leaves may be completely stripped to the mid-veins to skeletons. They may also feed on fruits causing small shallow hollows on the fruit surface. High numbers of these beetles can cause considerable damage.

 

What to do:
  • Hand pick and destroy adults and larvae. This is feasible in small plots.
  • Spray neem products. Neem extracts have repellent effects on these beetles. For instance, sprays with an aqueous neem seed extract (10g/l) at 10 days intervals showed repellent effect on Epilachna beetles in India (Ostermann and Dreyer, 1995).

  • Epilachna beetles (Epilachna spp.) larvae and pupae on eggplant. Larvae are about 6 mm long.

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org

  • Epilachna beetles (Epilachna spp.) larvae and pupae on eggplant. Larvae are about 6 mm long.

    © O.P. Sharma, NCIPM, New Delhi. India, Bugwood.org

Eggplant lace bug (Urentius hystricellus)

It is a small bug (about 3 mm in length), brownish in colour. Its body is covered with spines and the wings show a distinct lace-like appearance. Nymphs resemble adults, but are initially wingless, developing wings as they grow. Both adults and nymphs are usually found in groups on the underside of leaves. They suck sap from the leaves causing whitish to yellowish mottled patches on the leaves. In case of serious infestations the leaves turn entirely yellow and drop off. Attacked leaves are speckled with small black shiny spots, which are the faeces of the bugs.

 

What to do:
  • Spray neem products. They have given effective control of lace bugs on eggplants. The lace bug (Urenthius sp.) was repelled from eggplant plots treated with neem oil (5, 10 and 20%). However, concentrations of 10 and 20% showed phytotoxic effects.

    Weekly sprays of an aqueous neem seed extract (50 g/l) and 2% neem oil gave good results against another species of lace bug (Corythaica cyathicollis) attacking eggplant in the Caribbean (Ostermann and Dreyer, 1995).

  • Close-up of an adult of the eggplant lace bug (Urentius hystricellus). Real size: 3 mm in length.

    © M. Billah, icipe

  • Close-up of an adult of the eggplant lace bug (Urentius hystricellus). Real size: 3 mm in length.

    © M. Billah, icipe

Shoot and fruit borer (Leucinodes orbonalis)

It is a major pest of eggplant. The adult is a small moth, with a wingspan of 18-24 mm, white in colour with a pink and bluish tinge, and a few brown spots on its wings. Moths lay creamy white single eggs on leaf undersides, stems, flower buds, or the base of fruits. Upon hatching the caterpillars (white in colour) bore into the top section of fruits and tender shoots. Caterpillars develop inside fruits and stems reaching a length of 15-18 mm. When fully-grown, caterpillars make a small hole in the fruit or shoot and drop to the soil and pupate among fallen debris.

 

When plants start bearing fruits, most caterpillars prefer to feed on the tender fruits. The damage to the shoots is not seen until they droop as a result of the caterpillar feeding inside them. Recently damaged fruits are not easy to detect. The first indication of damage to the fruit is a small hole just below the calyx where the insect has entered. Fruits are filled with frass. They change colour and taste; they drop off and are unmarketable. Caterpillars are difficult to control with pesticides. Within hours of hatching from eggs, caterpillars enter the shoots or fruits, and are not reached by contact pesticides.

 

What to do:
  • Conserve natural enemies. Predatory ants are the main natural enemies of the shoot and fruit borer. Other natural enemies include: ladybird beetles, praying mantis, earwigs, predatory bugs and spiders.
  • Destroy old eggplant plants and stubble (burn or bury them) immediately after harvest. Pupae can survive in the stubble for several weeks, infesting the new crop.
  • Use healthy, pest-free seedlings. Raise seedlings far away from sources of infestation (old eggplant fields, eggplant stubble)
  • Grow seedlings under nylon netting to prevent moths from laying eggs on the plants.
  • Remove and destroy infested shoots (readily visible as dry tip of branches). Burn, shred into tiny pieces or bury attacked shoots at least 20 cm in the soil. If this is done by all farmers in a community, especially before fruiting, pest infestation and damage can be drastically reduced. Continue cutting attacked shoots at least once a week until the final harvest.
  • Destroy infested fruits found during harvest.

  • Eggplant fruit borer (Leucinodes orbonalis)

    © Koen V.N.Maes

  • Eggplant fruit borer (Leucinodes orbonalis)

    © Koen V.N.Maes

Bacterial wilt (Ralstonia solanacearum)

This disease occurs with bad drainage, especially in the hot, wet season and is often combined with symptoms of root-knot nematodes. Plants wilt and die suddenly. When newly infected stems are cut crosswise and placed in water, a greyish or yellowish ooze appears from the cut stem. The pathogen is soil-borne with a wide host range. Root-knot nematode infestation aggravates the disease development.


 

What to do:
  • Use resistant varieties, if available.
  • Use certified disease-free seeds.
  • Remove infected plants from fields and destroy affected plants.
  • Rotate with non-solanaceous crops (e.g. maize or beans).
  • Use raised beds for improved drainage.
  • Graft plants onto resistant rootstocks.

  • Bacterial wilt symptoms on potato plants. The first visible symptom on foliage is a wilting of the leaves at the ends of the branches during the heat of the day with recovery at night. As the disease develops, a streaky brown discoloration of the stem may be observed on stems 2.5 cm or more above the soil line, and the leaves develop a bronze tint.

    â’¸ A.A. Seif, icipe

  • Bacterial wilt symptoms on potato plants. The first visible symptom on foliage is a wilting of the leaves at the ends of the branches during the heat of the day with recovery at night. As the disease develops, a streaky brown discoloration of the stem may be observed on stems 2.5 cm or more above the soil line, and the leaves develop a bronze tint.

    â’¸ A.A. Seif, icipe

Powdery mildew (Leveillula taurica)

Symptoms appear as yellowish spots on the leaves. On the lower surface of affected leaves the spots are covered by a whitish growth constituting spores of the fungus. Affected leaves eventually dry up but do not fall off. The fungus is endophytic (grows within the leaf contrary to other powdery mildew fungi that are grow on surface of the leaves). It has a wide host range. It is not seed-borne but it survives on herbaceous weeds and other susceptible hosts. Temperatures slightly above 20 degC, dry conditions and fairly high relative humidity favour disease infection. However, fungal dispersal takes place mainly at low humidity.

 

What to do:
  • Use of resistant varieties, if available.
  • Use overhead irrigation.
  • Use sulphur sprays.

  • Powdery mildew (here on tomato)

    â’¸ A. A. Seif, icipe

  • Powdery mildew (here on tomato)

    â’¸ A. A. Seif, icipe

Anthracnose (Colletotrichum melongenae)

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 30°C.

What to do:
  • Use resistant varieties, if available.
  • Use certified disease-free seeds.
  • Practise crop rotation.
  • Destroy infected crop residues.
  • Anthracnose symptoms on eggplant

    Anthracnose symptoms on eggplant, following artificial inoculation via needle puncture of fruit.

    © Anna L. Snowdon. Reproduced from the Crop Protection Compendium. CAB International, Wallingford, UK, 2004.

  • Anthracnose symptoms on eggplant

    Anthracnose symptoms on eggplant, following artificial inoculation via needle puncture of fruit.

    © Anna L. Snowdon. Reproduced from the Crop Protection Compendium. CAB International, Wallingford, UK, 2004.

Phytophthora fruit rot (Phytophthora parasitica)

Phytophthora fruit rot fungus can cause damping-off in seedbeds, leaf spotting and collar rot on the main stem final resulting in plant death. The fungus may attack fruit at any growth stage and any part of the fruit. Spots on the fruit are dark brown, water-soaked and may have a light-coloured border. A whitish mould develops on the spots when wet conditions prevail. The spots are neither sunken nor exhibit concentric rings (zonation). Infected fruits drop prematurely.

 

The fungus is soil-borne. It is spread in the field by run-off water and farm implements. The disease is favoured by prolonged periods of high moisture and temperatures near 30° C.

 

What to do:
  • Avoid dense planting.
  • Remove and destroy diseased fruit and plants.
  • Plough deep because Phytophthora would not survive.
  • Practise crop rotation with non-solanaceous crops such as tomato, potato and peppers.
  • Where practical, add copper sulphate to irrigation water.

  • Phytophthora_parasitica_host_symptoms

    (c) Supattra Intavimolsri Department of Agriculture, Thailand

  • Phytophthora_parasitica_host_symptoms

    (c) Supattra Intavimolsri Department of Agriculture, Thailand

Late blight (Phytophthora infestans)

The late blight fungus affects tomatos, potatoes and eggplants but not pepper. Its symptoms consist of brown spots with purplish tinge and they can develop on leaves, stems, branches and both green and ripe fruits. In moist weather it can cause complete defoliation and rotting of fruits.

 

What to do:
  • Use resistant varieties, if available
  • Practise rotation with non-solanaceous crops (e.g. tomato, potato, peppers etc) for 3 to 4 years. However, this will only be effective if it is done in cooperation with neighbouring farmers since the fungal spores can travel quite large distances by wind.
  • In wet weather, copper fungicides, could be applied as soon as the disease is observed or as soon as local experience suggests that the weather conditions are favourable for disease development.

  • Phytopthora infestans on potato tuber

    (c) Fry W, EcoPort

  • Phytophtora infestans on tomato

    (c) Laing MD, EcoPort

  • Phytopthora infestans on potato tuber

    (c) Fry W, EcoPort

  • Phytophtora infestans on tomato

    (c) Laing MD, EcoPort

Fusarium wilt (Fusarium oxysporum f.sp. melongenae)

Affected plants show yellowing of leaves that progressively wilt and die from bottom upwards. Woody stem and root tissue of diseased plants turn brown. This fungus does not affect tomatoes. Optimum temperature for its growth on eggplants is 27.8 °C.

 

What to do:
  • Use resistant varieties, if available
  • Amend soils with organic matter (e.g. compost)
  • Practice crop rotation
  • In some countries susceptible eggplant varieties are grafted onto resistant rootstocks (e.g. Solanum gilo and S. integrefolium).

  • Bacterial blight blackening of veins (here on okra)

    © A.M. Varela & A.A. Seif, icipe

  • Bacterial blight blackening of veins (here on okra)

    © A.M. Varela & A.A. Seif, icipe

Early blight or Alternaria leaf and fruit spots (Alternaria spp.)

Several Alternaria spp. are involved. These include A. melongenae, A. solani and A. tenuis. They cause leaf spotting and fruit rots. They produce leaf spots with concentric rings. The spots are mostly irregular, 4 to 8 mm in diameter and may enlarge and cover a large area of the leaf blade. Severely infected leaves drop off prematurely resulting in the reduction of yield. Fruit spots are circular, brown, dry and hard.

 

What to do:
  • Observe proper field sanitation.
  • Use certified disease-free seed.
  • Own seed should be water heat treated. For more information on Hot water treatment click here.

  • 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.

    © A.M. Varela & A.A.Seif, icipe

  • 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.

    © A.M. Varela & A.A.Seif, icipe

Information Source Links

  • AIC, Nairobi, Kenya (2000). Local and Export Vegetables Growing Manual.
  • AVRDC, the World Vegetable Center (2003). Harmful and helpful insects in eggplant fields. www.avrdc.org
  • AVRDC, the World Vegetable Center. (2003). How to control eggplant fruit and shoot borer. www.avrdc.org
  • Beije, C.M., Kanyangia, S.T., Muriuki, S.J.N.,Otieno, E.A., Seif, A.A., Whittle, A.M.(1984). Horticultural Crops Protection Handbook. National Horticultural Research Station, Thika KEN/75/028 and KEN/80/017
  • Bohlen, E. (1973). Crop pests in Tanzania and their control. Federal Agency for Economic Cooperation (bfe). Verlag Paul Parey. ISBN: 3-489-64826-9
  • CAB International (2005). Crop Protection Compendium, 2005 Edition. Wallingford, UK www.cabi.org
  • Chen, N.C., Kalb, T., Talekar, N.S., Wang, J.F., Ma, C.H. (2002). AVRDC Training Guide: Suggested Cultural Practices for Eggplant. www.avrdc.org
  • Critchley, B. R. (1995). Manual for the Integrated Pest Management of diseases, insects, nematodes and weeds of garden egg, okra, onion, peppers, and tomato in Brong Ahafo, Ghana. Natural Resources Institute (NRI). UK
  • East African Seed Co. Ltd. Africa's Best Grower's Guide www.easeed.com
  • El Shafie, H. A. F. (2001). The use of neem products for sustainable management of homopterous key pests on potatoes and eggplants in the Sudan. PhD thesis. Institute of Phytopathology and Applied Zoology. Justus Liebig University of Giessen.
  • National Research Council. 2006. Lost Crops of Africa: Volume II: Vegetables. Washington, DC: The National Academies. Available online www.nap.edu
  • Nutrition Data www.nutritiondata.com.
  • Ostermann, H., Dreyer, M. (1995). Vegetables and grain legumes. In: The Neem tree Azadirachta indica A. Juss. and other meliaceous plants sources of unique natural products for integrated pest management, industry and other purposes. Edited by H. Schmutterer in collaboration with K. R. S. Ascher, M. B. Isman, M. Jacobson, C. M. Ketkar, W. Kraus, H. Rembolt, and R.C. Saxena. VCH. pp. 392-403. ISBN: 3-527-30054-6
  • 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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