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The pod weevil (Piezotrachelus varius or Apion varium). Its a common pest of cowpeas in West Africa. Generally 13-26% of the pods are damaged. Losses of seeds up to 92% have been reported in Nigeria.
The shiny black weevils bore holes in fresh green cowpea pods and lay eggs into the pods.
The grubs feed on the seeds and pupate within the pods.
What to do:
(Callosobruchus spp.)
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Adults are 2.0-3.5 mm long. They are also known as the cowpea seed beetles and are the principal storage pest of cowpea.
These bruchids may infest up to 100% of the stored seeds within 3 to 6 months under ordinary storage conditions.
A positive relationship between pod damage by field pest (pod sucking bugs and pod borers) and bruchid infestation in storage was found in Uganda.
Controlling pests infesting pods of cowpeas in the field significantly reduce bruchid carryover in storage (IPM CRSP).
What to do:
(Maruca vitrata)
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This is the most important pod borer pest, causing severe damage to cowpeas. Losses over 80% have been reported on indigenous varieties and even on high yielding varieties.
Moths usually lay eggs on flower buds, flowers, or on terminal shoots of young plants.
Young caterpillars may feed on any part of the flowers or foliage. Several young caterpillars may be found together among flowers.
Older caterpillars are highly mobile, feeding continuously on flowers and newly formed pods, causing severe damage to the crop.
Upon reaching maturity the caterpillars drop from flowers or pods onto the soil and pupate beneath the plant under leaf debris.
Caterpillars of the legume pod borer are dull to yellow-white and often reach a length of 1.8 cm.
Each segment has dark spots that form a distinct series along the length of the body. The head is dark brown to black.
What to do:
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There are several pod sucking bugs. The tip wilter (Anoplocnemis curvipes), the spiny brown bug (Clavigralla tomentosicollis, Riptortus bugs (Riptortus dentipes), Mirperus jaculus, the green stink bug (Nezara viridula) and Aspavia sp.
These bugs attack cowpeas in Africa. The spiny brown bug Clavigralla tomentosicollis and Riptortus dentipes are the most important, causing serious damage.
Nymphs and adults attack young, tender pods and causing shrivelling and rotting of pods and malformation of seeds, which lose viability.
Bugs are difficult to control since they usually feed on a wide range of crops and are very mobile.
What to do:
(Megalurothrips sjostedti and Frankliniella schultzei)
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Thrips are among the most widespread and important pests of cowpeas in Africa. The cowpea flower thrips or African bean flower thrips (Megalurothrips sjostedti) causes yield losses of up to 100%.
During the pre-flowering period, nymphs and adults of this thrips may damage the terminal buds.
However, the main damage is on the flower buds and flowers. Attacked flower buds become brown and eventually fall off, leaving behind dark red scares.
Damaged flowers are distorted, malformed and show decolouration and may fall off. Infested on pods are malformed.
What to do:
(Aphis craccivora)
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It is a widespread pest of cowpeas. Aphids suck sap on stems, terminal shoots and petioles of seedlings, and on pods and flowers of mature plants.
A heavy attack can cause death of young seedlings, stunting and delay in flowering on older plants.
However, it is more important as vector of virus diseases (e.g. the cowpea mosaic virus).
What to do:
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Scientific Name: Vigna unguiculata
Order / Family: Fabales: Fabaceae
Local Names: Kunde (Swahili, Kipsigis), Mathoroko (Kikuyu), Likhuvi (Luhya), alot-bo (Luo), Nthooko (Kamba), Egesare (Kisii), Kiyindiru (Luganda)Common Names: Yard long bean
Pests & Diseases: African bollworm , Anthracnose, Aphids, Bacterial blight, Brown blotch, Bugs , Charcoal rot, Cowpea mosaic diseases, Cowpea weevil, Cowpea wilt, Damping-off diseases, Flower or blister beetles, Leaf spots, Legume pod borer, Powdery mildew, Purple witchweed, Root-knot nematodes, Rust, Southern blight, Storage pests, Thrips
Other pests: Bean fly, Foliage beetles, Whiteflies
Cowpeas are basically annual crops grown for their leaves and seed.
The growth habit is climbing, spreading or erect and they belong to the bean family (Leguminosae) (Papilionaceae). Cowpeas are native to Africa where they were domesticated over 4000 years ago.
The crop exhibits much variation in growth habit, leaf shape, flower colour and seed size and colour.
Cowpeas are mainly important in the marginal rainfall areas because they are well adapted to dry climate and suitable for a variety of intercropping systems.
Cowpeas are cultivated for the seeds (shelled green or dried), the pods or leaves that are consumed as green vegetables or for pasture, hay, silage and green manure.
Tender cowpea leaves and shoots contain 4% protein, 4% carbohydrates and are rich in calcium, phosphorus and vitamin B. Dried seeds contain 22% protein and 61% carbohydrates.
The leaves may be dried and stored for later use. Cowpeas that are sprayed with pesticides should not be eaten as leaves unless pre-harvest intervals are followed.
In Africa, where cowpeas are the preferred food legume, they are consumed in three basic forms:
Cowpeas are generally tolerant to drought and low light conditions, but are very susceptible to a variety of insects and diseases and do not do well in poorly drained and cool areas.
Local land races of cowpeas grown by farmers in West Africa are well adapted so that they start to flower at the end of the rains at a particular locality.
The optimum temperature to their growth and development is 20 to 35degC.
Cowpea can grow in a wide range of soils, well adapted to light sandy soils where most other crops produce poorly, and they do well on acid soils.
On heavy fertile soils they show a vigorous vegetative growth, but not necessarily a good grain yield.
Most varieties need a minimum rainfall of 200 mm during a growing season.
Cowpeas seeds are planted about 20 to 40 cm apart and are often grown as an intercrop with pearl millet, sorghum or maize at wide spacings (total plant population 10,000-20,000 plants per ha).
When produced as a green vegetable, they are commonly grown as a monocrop in rows 30 to 40 cm apart with 8 to 12 cm between plants. Some very drought resistant types may grow for two seasons in the farm.
Tillage normally follows the crop with which cowpeas are interplanted. When sown in rows the seed-rate is 10-40 kg/ha.
| Variety | Maturity Days | Target areas of production | Potential grain yield (t/ha) | Remarks |
| “Machakos 66” (M66) | 85-95 | Medium and higher altitudes 1200-1500 m above sea level | 1.5-1.8 | Dual purpose; creamy brown grains and good for intercropping; tolerant to cowpea yellow mosaic virus (CYMV) and scab; moderately tolerant to Septoria leaf spot and powdery mildew |
| “Katumani 80” (K80) | 75-85 | Drier areas or areas below 1500 m above sea level receiving less than 200 mm rain per season | 1.8-2.0 | Dual purpose; grains creamy brown; resistant to aphids; moderately tolerant to thrips, pod borers and leaf hoppers; susceptible to CYMV |
| “KVU 27-1” | 70-90 | 600 – 1200 m | 1.5-1.8 | Dual purpose; dark red grains; moderately tolerant to aphids, thrips, pod borers and leaf hoppers; moderately resistant to foliar fungal diseases and CYMV |
| “KVU-419” | 65-72 | Areas below 1200 m receiving less than 200 mm rain per season | 1.2-1.5 | Grain variety; smaller seed than both “M66” and “K80”; tolerant to cold and recovers very fast from drought |
| “KVU HB 48E 10” | 85-95 | Medium and higher altitudes 1200-1500 m above sea level | 1.2-1.4 | More vegetable type than grain type; tolerant to virus diseases |
| “KCP 022” | 60-75 | 0-1200 m | 1.2-1.5 | Drought tolerant |
| “MTW 63” | 60 | 1-1500 m | 2.5 | Pest tolerant |
| “MTW 610” | 60 | 1-1500 m | 2.5 | Large grains |
| “Kunde 1” | 75-90 | Below 2000 m | 1.2-2.5 | Dual purpose |
| “ICV” | 75 | 1-1500 m | 2.2 | Pest tolerant |
| “Ngombe” | Semi spreading, good for green leaf production, sweet taste of grain | |||
| Local varieties(land races) | 0.3-0.5 | Varying colours and spreading or semi spreading |
Most cowpea crops are rain-fed, a few are irrigated and others use residual moisture in the soil after harvest of a rice crop. Cowpeas are particularly well suited for rice-based cropping systems.
Two to three weedings during the first 1.5 months after planting are recommended. Losses due to weeds can be 30-65%. Parasitic weeds, such as Striga gesnerioides (Purple withweed), generally associated with continuous cropping of cowpeas in Africa, may also cause severe damage.
One additional benefit of cultivating cowpeas is their ability to fix atmospheric nitrogen in root nodules through symbiosis with Rhizobium bacteria that are common in most soils.
An effective cowpea-Rhizobium symbiosis fixes more than 150 kg/ha of N and supplies 80-90% of the total N required. Inoculation may be advantageous, if the crop has not been grown for many years.
In general, no fertilisers are applied. Cowpeas are commonly incorporated in crop rotations in semi-arid, humid and subhumid environments.
A cowpea crop of the leafy types grown before a maize or millet crop and incorporated green into the soil, can produce a good grain crop without any addition of more nitrogen.
Intercropped cowpeas also share nitrogen with the other crops e.g. maize, millet, sorghum and cotton). For intercropping choose a cowpea variety carefully – the spreading types may over power other crops such as cotton by entangling their branches and interfering with fieldwork.
Cowpeas do not normally respond to nitrogen or phosphorus fertilisers, so none need adding. However where soils are highly eroded an application of 5 tons/ha of dry compost or manure is beneficial.
Weed during early stages of crop, later the cowpeas will cover the ground and suppress weeds including purple witchweeds.
Two weedings are recommended, one two weeks after emergence and the second weeding just before flowering.
Leaves for eating must be young and tender. Three leaf pickings (starting 2 1/2 -3 weeks after planting at weekly intervals have little effect on grain yields of five to six 90 kg bags of seed per acre.
Green pods are harvested by hand when they are still immature and tender (12-15 days after flowering). When grown as a grain, harvesting is complicated by the prolonged and uneven ripening of many cultivars.
Time of harvesting is critical as mature pods easily shatter, so hand-picking can be advantageous. Sometimes plants are pulled when most of the pods are mature. For hay, the crop is cut when most of the pods are well developed.
Leaves and seeds widely used as food. Some communities grow cowpeas mainly as a vegetable (Luhya). Young leaves are often cooked with Potash. The vegetable may be cooked alone or with other vegetables, mainly Corchorus olitorius and C. trilocularis (mlenda). The leaves are cooked with Corchorus spp. Leaves, milk and butter added and served to breast feeding mothers (Luo). Leaves are normally eaten with ugali or mashed with maize and potatoes or other pulses (Kikuyu). The seeds may also be boiled and eaten alone (Luo) or mashed and butter added. Cowpea leaves may be dried and stored for several months. Cowpea is a major leafy vegetable among the Mijikenda, often mixed with leaves of sweet potato, cocoyam, pumpkin and Corchorus olitorius.
It’s a good animal fodder, roots are reportedly very poisonous
Ascochyta pisi, A. pinodella/Mycosphaerella pinodes
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Peronospora pisi
Fusarium oxysporum f. sp. pisi
Pea enation mosaic virus (PEMV)
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