Scientific Name: Solanum villosum, S.americanum, S. scabrun,
Order / Family: Solanales:
Black nightshade, Narrow-leaved nightshade
Pests & Diseases: Aphids, Early blight, Spider mites
Other pests: Bacterial wilt, Root-knot nematodes
Pests and diseases are similar to those of Solanaceae family (e.g. peppers, potatoes and tomatoes), therefore for more information see also under these crops
Many farmers in Kenya have realized the hidden treasure of this leafy indigenous vegetable called the African Night Shade. Growing Managu has become a lucrative venture for both women and youth in the rural areas. The crop takes a short period of time to start paying back the original capital with little management, making it a viable agribusiness.
The plant is an erect, many-branched herb growing 0.5 to 1.0 m high. Managu bears thin, oval, slightly purplish leaves up to 15 cm in length. The plant has numerous white flowers and usually purple to black round berries about 0.75 cm in diameter containing many small, flattened, yellow seeds.
There are several species with black berries, but the most popular are those with orange berries belonging to Solanum villosum. This group of species is often erroneously referred to as Solanum nigrum, a poisonous plant from Europe that is not usually grown in Africa (AVRDC 2003).
Managu leaves are eaten as a cooked vegetable, often mixed with other vegetables and the fresh fruit is also consumed. Some Solanum varieties are preferred for their bitter taste while others are considered ‘sweet’, particularly after being boiled and the water discarded. The raw leaves contain 4% protein, 6% carbohydrates and are moderately high in vitamin C.
Solanum species that are found in Kenyan vegetable gardens include S. macrocarpon, S. scabrun and S. villosum.
Solanum plays an important role in traditional medicine in Africa and elsewhere, but the leaves are considered poisonous in some areas of the world so one should be careful about obtaining seeds for planting. Let’s get to know how to grow Managu…
Climatic conditions, soil and water management
Managu/African nightshades can grow in a wide range of soil types but does not tolerate drought (AVRDC 2003). African nightshades does well in organic plots.
Propagation and planting
African night shade can either be directly planted in a well prepared field by seed or first raised in a nursery bed for transplanting.
- Direct planting;
Planting in lines:
- Use a string to make rows in your field. Spacing between rows should be 30cm.
- Using a stick to make a 1cm deep farrow following the string.
- Mix seed with soil/manure in a ratio of 1:4 (1 quantity of seed to 4 quantities of soil/sand) before planting to avoid congestion and seed wastage.
- Plant the seed in the farrow and cover with light soil.
- Managu are propagated from seeds. Seeds are marketed by Simlaw Seeds in Nairobi under the name “Black Nightshade” in 25 gram packets. You can also visit local agro stores in your town for seeds from other companies.
- Raising seedlings in the Nursery;
- The soil in the nursery should be loosened and enriched with decomposed manure.
- Managu seeds should be mixed with sand or ash for uniform sowing.
- Sow the mixture thinly, either by broadcasting or in rows, 15 – 20 cm apart and cover with a thin-fine layer of soil.
- After sowing, the shade is erected 2 feet/ 60cm above the bed.
- The bed should be mulched with tall grass or a similar material to retain moisture (Mulching is also important to prevent the seeds from splattering around when irrigating the bed especially during the rainy season).
- Germination is after 7-14 days.
- Hardening off is done starting on the 3rd week after sowing by slightly reducing the shade and also reducing the rate of water application. Eventually, the shade will be fully removed on the 4th week to expose the seedlings into the external environment once the seedlings attain 3cm high. This will also depend on the weather.
- Transplant when seedlings have 6 true leaves and are 10 – 15 cm tall. The spacing should be 20 cm in the row by 40 cm between the rows.
Weeding and thinning
- Timely weeding will lead to increased yield.
- Timely weeding minimizes competition for food and light between weeds and African nightshade. It will give African nightshade better conditions to grow.
- Weeding also reduces pest and disease infestation at the early stages which will lead to increased yields.
- Weeding should be done as soon as weeds emerge and before the flowering of weeds. This will reduce the risk of weeds spreading.
- Thinning is done at the time of weeding. During thinning the less vigorous, off-types or relatives and diseased plants are removed. The good quality thinned plants can be sold or consumed at home.
- Rouging of off-types should be done at flowering and at fruiting (early maturity) when it is easy to identify the off-types.
Nightshades require large amounts of nitrogen, and therefore do well in soils that are rich in organic matter. They also grow well on land covered with ash from recently burned vegetation (AVRDC 2003). Apply organic manure where possible. Frequent irrigation is needed for good yields.
A healthy Black African night shade.
Pest and Disease Management
Pest and disease management should be a continuous effort by the farmer to ensure early intervention in case of an outbreak.
Both organic and inorganic pesticides can be used to control pests and diseases.
It is recommended to always seek advice from an agriculture extension worker on pest and disease identification and management.
Note: The farmer should monitor the field to ensure quick action is taken in case of break out of pests and diseases.
African night shade is not a drought tolerant crop. It requires optimal moisture for a better performance. It can be grown in rain fed areas or irrigated in dry areas. Irrigation can be drip or overhead.
The crop does well when manure or compost is used. Since the crop is a leafy vegetable, it therefore requires a lot of nitrogen.
African nightshade is ready for harvesting starting from 4 weeks after transplanting. The crop can be harvested in two ways:
1. Uprooting (Week 10-11): This is mostly done in commercial production by uprooting the whole plant.
2. Cutting tender stems (Week 12-16): This is commonly done in kitchen gardens for home consumption. The tender stems are cut every 1-2 weeks until the plant flowers.
Managu is ready for harvest 4 weeks from transplanting. The stems are cut approximately 15 cm above the ground. This allows new side shoots to develop. Picking is done at weekly intervals.
If complete harvesting is practiced, spacing can be as close as 10 x 10 cm and plants are uprooted. This method is mainly used when there is less than 2 months before the main staple food crop will be planted. Roots of these crops can be kept in water to keep the plants fresh.
Picking should be done very early in the morning and the produce sold the same day. Alternatively, Managu can be harvested late in the afternoon and placed on plastic sheets or banana leaves. These should be tied in small bundles.
The flowers should be removed before the crop is taken to market. Water these bundles sparingly to retain freshness.
How to preserve vegetables
There are several ways to preserve vegetables as explained below:
- Local refrigeration: This is a 1m high construction made of bricks with 2 separate walls and sand/charcoal dust between the walls, preferably under a shade. Add an elevated water tank and use a small pipe to allow water drip to keep the sand/charcoal dust moist. The vegetables should be placed inside the structure on racks.
- Preservation using a pot: African indigenous vegetables can also be stored for future consumption by placing harvested vegetables in a pot under a shade. Pile sand or charcoal dust around the pot and continue to keep the sand charcoal moist by regularly adding water. Do not pour water in the pot.
- Preservation using a solar dryer:
Vegetables can also be preserved by drying them using solar dryers after which they will be packaged for use during the dry season. Though vegetables can be dried traditionally under the sun, more nutrients are lost compared to the use of solar dryers, and it is therefore not a recommended practice.
Pests and diseases
Pests are similar to those of Solanaceae family (e.g. peppers, potatoes and tomatoes), therefore for more information see also under these crops.
- Aphids (Aphis spp.)
Aphids on the lower side of a leaf.
Aphids are a major pest mostly found underneath of a leaf, causing leaves to curl and become unattractive to customers.
Aphids feed by sucking plant sap. Small aphid populations may be relatively harmless, but heavily infested plants usually have wrinkled leaves, stunted growth and deformed pods. Plants, in particular young plants, may dry out and die under heavy aphid attack. Heavy attack on older plants may cause crop loss by decreasing flower and seed production. Damage may also reduce seed viability.
- Conserve natural enemies. They are important in natural control of aphids e.g. Lady bird.
- Monitor regularly the crop.
- Whenever necessary spray only affected plants (spot spraying).
- Use bio pesticides that are not harmful to natural enemies (for instance neem, ashes, soapy water). In Kenya, foliar sprays with neem products such as Neemroc (r) (1-3%) and Neemros(r) water extract (50 g/l) controlled the black bean aphid on French beans (Maundu, 1997).
Spider mites (Tetranychus spp.)
The plant’s leaves and growth tips are susceptible to mites (very small, sucking arthropods) that result in twisted growth and low productivity.
Generally, spider mites feeding may cause reduction in plant growth, flowering, number and length of berries, and number of seeds per berry. Damage is most severe when mites attack young plants. Mite damage may be particularly severe during the dry season.
- Avoid planting next to infested fields.
- Avoid use of broad-spectrum pesticides, in particular pyrethroids; this may lead to spider mite outbreaks.
- Use overhead irrigation or wash plants with a strong jet of water to knock off mites and destroy their webs. Be sure to spray the underneath of the leaves. However, this should be done early in the day to allow the foliage to dry. Wetness of the foliage for an extended period is conducive to development of fungal diseases.
Diseases are similar to those of Solanaceae family (e.g. peppers, potatoes and tomatoes), therefore for more information see also under these crops.
- Early blight
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. Early blight thrives best under warm wet conditions. Leaf spots first appear on the oldest leaves and progress upward on the plant. Entire plant could be defoliated and killed.
- Harvest/ prune the crop regularly to avoid overcrowding. This will facilitate good aeration and prevent excessive humidity underneath.
- Maintaining high standards of hygiene and keeping the crop free from weeds.
NB: Controlling early blight once it has established is very difficult. The most important way of controlling early blight is attempting to prevent its establishment and further spread.
What to do:
- Rotating with other crops like amaranth is essential. Do not rotate with tomato, potato or peppers as these belong to the same family and susceptible to the same diseases.
- In areas with a high humidity, wider plant spacing should be used.
- Practice good field hygiene. Remove infected leaves during the growing season and discard all badly infected plant debris at the end of each season.
- Use certified disease-free seeds
- When using own seeds, use hot water to treat the seeds.
By Arthur Shadrack,
Agronomist, FARMLINK KENYA.
For more farming articles on crop production visit our website www.farmlinkkenya.com