I.   Topic

Cowpeas are grown most extensively in the sub-Saharan portion of Aftica.  They are used primarily as a protein source in human diets.
 

	To learn the origin of cowpeas and their distribution.
	To understand the climatic and edaphic requirements for cowpea production.
	To appreciate the importance and utilization of cowpeas in a cropping sysyem.

Cowpeas are a native of Central Africa.  They are grown extensively in the sub-Saharan region of Africa, and are planted in association with sorghum.  The sorghum/cowpea intercrop is the most important cropping system in this region.  Cowpeas grow during the humid rainy seaso in the tropics and sub-tropics.  Cowpeas are a short-day-warm weather crop.

In developed countries, cowpea is used largely as a silage crop for animals and is equal to red cover hay in nutritive value.  Cowpeas can also be used as a green manure and soil improving legume.  In developing countries, cowpeas are used for human nutrition and the residue is fed to animals.

Since cowpeas grow well in poor soils, can grow with little fertility, can stand hot temperatures, and can fix atmostpheric nitrogen, they are a natural for much of the semi-arid tropics.  Cowpeas are not important legumes elsewhere.  Where, like sorghum, in areas with better growing conditions, other crops have the advantage.

IV.    Economic Importance

1. World:

• 1.2 million metric tons on 3 million ha.  Produced in Africa, Southern Europe and Southern Asia.  Countries leading the production are: Nigeria, Niger, and Upper-Volta (West Africa.

• Production: 50,000 tons (l969)
• Acreage: 30,000 ha (l970)

1. Native of Central Africa.

2. Was introduced in NC in 1714 and spread throughout the southern states later.

Adaptation

1. Climatic requirements:

• Grown primarily under humid conditions
• Is a short-day-warm-weather crop
• Grown as far north as Southern Illinois, Indiana, Ohio, and New Jersey
• Sensitive to frost in fall and spring

• Adapted to a wide range of soils
• Requirements: good drainage and presence of, or inoculation with, the proper N-fixation bacteria culture

1. Species:

• Vigna sinensis - related sub-species: Asparagus bean (Vigna Sinensis var sesquipedalis) and catjang (V. Sinensis var. Cylindrica).

• Annual herbaceous legume.  Plants are viny or semi-viny, fairly leafy with trifoliate leaves.
• Growth habit indeterminate
• Plant continues to blossom and produce seed until checked by adverse environmental conditions.

• White or purple
• Are borne in pairs in short racemes

• Smooth, 8-12 inches long, cylindrical and somewhat curved

• Uniformly colored or multicolored
• Buff, clay, white, purplish, or nearly black, with a second color usually concentrated about the hilum

• Largely self-pollinated.  Natural crosses are rare in the field

1. Seeding practices:

• For best results, should be planted in warm soil after all danger of frost is past
• In the south, it may be planted as late as August 1 or up to 90 days before the first frost
• In Northern Virginia, should be planted in May or early June for seed and late June for best yields of hay
• In California, best planted between May 1 and June 15
• Commonly planted in rows 24 to 40 inches apart with the seeds 2 to 3 inches apart in the row

• For hay: May be harvested when pods begin to turn yellow.  The best quality of hay is obtained when pods are fully grown and a considerable number of them are mature
• For seeds: Should be harvested when ? or 2/3 of the pods have matured

• Often with corn for silage.  Also with sorghum, sudan grass, or Johnson grass for hay.

• Is grown in corn and cotton rotation in the South to supply N and organic matter to the soil

1. Silage crop: Largely used as a silage crop.  Considered equal to red clover hay in nutritive value when well cured.    Although high in protein and low in carbohydrates, will make good silage alone when wilted to the proper moisture content of 60-68% before being put into the sills.

2. Soil improvement in the southern states: On very poor soils, it is advised to plow under the entire crop in the green state.

3. Food crop: Seed of certain varieties is a popular food in the South, being used in the pod, shelled green, or shelled dry.

4. Livestock food: Although high in feed value, cowpea seed is generally not an economical livestock feed.  Also used as pasture.

Disease

1. Cowpea wilt: Caused by Fusarium oscejsporium var tracheiphilum.  Causes the leaves to yellow and fall prematurely and finally results in the death of the plant.  The best control measure is the use of resistant varieties.

2. Cowpea root rust: Caused by a nematode (Meloidogyne sp).  The best control measure is the use of resistant varieties in combination with other immune crops in rotation.

3. Bacterial blight or canker caused by Xanthomonas vignicola:   Several resistant varieties exist.

4. Others:

• Charcoal rot caused by macrophomina phaseoli
• Zonate leaf spot (Aristastoma conomicum)
• Red leaf spot (Cercospora corienta)
• Mildew (Erysiphe polygoni)
• Red stem cauker (Phytophthora cactorum)
• Viruses diseases (cucumber mosaic, southern bean mosaic, curly top)

1. Major insect enemies:

• Cowpea weevil (Callosobruchus maculatus) and the southern cowpea weevil or four spotted bean weevil (Mylabris quadrimaculatus).  They lay their eggs on the pods or in the seeds.  The larvae bore into the seeds and complete the life cycle there.  Control: Insecticide application; fumigation or heat treatment of the stored seeds.
• Cowpea Cuculus (Chalcodermus sermus) infest developing seeds.  Control: Insecticides application when blossom begins.

V.   Summary

Cowpeas grown in association (inter cropped) with sorghum supplies the primary source of human diet in many of the poorest countries in the world.  Both crops grow in areas of high temperatures and low fertility.  They have a similar growing season and moisture needs.  The cowpea (a legume) can fix nitrogen via symobtic N fixation in the nodules of its roots.  The N-fixing bacteria trade a place to live for N in the legume.  This N fixation provides some N for the associated sorghum crop, and the sorghum provides some micro-climatic shade (cooling) and weed control for the cowpea.  The two crops compliment each other in diet as well, with the cowpea supplying the protein and the sorghum supplying the energy.
 

  Last updated January 23, 2008