COWPEA (Vigna unguiculata)
AGRICULTURAL SCIENCE

COWPEA (Vigna unguiculata)

The cowpea is a member of the pulses or legumes. It belongs to the family called Leguminosae. It is rich in proteins and is commonly fed on by man. The fruit of cowpea is called pod.

 

Land Preparation

The land is cleared after which the thrash is packed. Weed-row burning can also be done. The land preparation is continued with stumping, ploughing, harrowing and ridging done in sequence.

 

Varieties/ Cultivars

Erect type, creeping type, Ife brown, Ife bimpe, etc.

 

Climatic and Soil Requirement: Cowpea requires a temperature of 27°C – 35°C, rainfall of 60cm – 125cm per annum, abundant sunshine and a rich sandy loamy soil.

 

Method of propagation: By seeds.

 

Planting date: Early and late planting are in April and August respectively. In the South, early planting is April while late planting is August and September. In the North, late planting is July and August.

 

Seedrate: 20 – 25 kg/ha.

 

Spacing: It depends on variety. For example, spacing for the spreading type is 25 x 9,0cm while the erect type is 30 x 75 cm.

 

Planting: There should be seed dressing before planting. Planting can either be manual or mechanised. Seeds are planted directly on the field. Planting depth of 2 – 4 cm is allowed. Planting rate is two to three seeds in a hole, while germination occurs between three to five days after planting.

 

Cultural Practices

  • Thinning: This can be done when the plants are about two to five weeks of age.
  • Weeding: Weeding can be done manually on a small scale while herbicides can be applied on commercial scale. Weeding is usually carried out once or twice before the plant spreads fully.
  • Fertilizer application: Apply phosphatic fertilizer for nodulation and pod formation. Apply the fertilizer at land preparation or at planting. Rate of application should be 250 kg or five bags per hectare.

 

Maturity period: Cowpea matures between three to four months after planting.

 

Harvesting: Brown, mature or ripe pods are harvested by hand-picking. Early maturing varieties are harvested three months after planting while late maturing varieties are harvested after four months. Harvest mature dry pods before shattering.

 

Processing: Harvested pods are dried under the sun. Shelling is done by beating the dry pods with sticks or by pounding lightly in a mortar on a small scale. Shellers are used on a large scale. Winnowing is carried out whereby broken shells or pods are removed from the beans. Extraneous matter like stones are later removed.

  • Ensure proper drying before storage.
  • Shelled beans are treated with insecticides before storage to prevent weevil’s attack.
  • Shelled seeds are stored in bags or rhumbus on a small scale.
  • Storage is done in silos on a large scale.
  • Hermatic storage can also be done in airtight containers.

 

Storage: The seeds are stored in jute bags.

 

Pests of Cowpea

1) Pod borers: Adults pierce or bore holes into fruits and stems and may inject toxic saliva.

Control

  • Spray with insecticide.

 

2) Bean beetle (Callosobruchus spp): This is a field-to-store pest. Adults and nymphs bore holes into seed, feed on them and turn them to powder, thereby reducing the quality and market value.

Control

  • Early harvesting of pods
  • Fumigation of containers or store with fumigant like phostoxin tablets.

 

3) Leaf Hoppers: They eat up the leaves, thereby causing low yield of crops.

Control

  • Spray plants with insecticides.

 

Diseases of Cowpea

1) Cowpea mosaic disease: It is a viral disease which is transmitted by aphid or thrip. It causes stunting, reduces pod size and causes premature dropping of flowers.

Control

  • Use resistant varieties.
  • Control insect vector by spraying with pesticides.
  • Remove and burn infected plants.

 

2) Bacterial blight: It is caused by a bacterium which is spread by water. Infected leaves produce water-soaked spots which later enlarge and turn brown.

Control

  • Use resistant varieties.
  • Use clean seeds when planting.

 

3) Nematode disease: It is caused by a nematode transmitted through soil. It causes twisting, rolling of leaves, galls and rottening of roots.

Control

  • Use resistant varieties.
  • Practise good cultural operations.
  • Treat soil with nematicide.

 

4) Damping-off disease: This disease is caused by a fungus (Phytophthora spp). It is transmitted through the hyphae in the soil. It results in the destruction of seedlings in the soil.

Control

  • Dress seeds with fungicides.
  • Practise crop rotation.
  • Grow resistant varieties.
  • Remove infected plants.

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