COCOA (Theobroma cacao)
AGRICULTURAL SCIENCE

COCOA (Theobroma cacao)

Cocoa is a beverage crop used in the preparation of many food drinks like Ovaltine, Bournvita, Pronto, etc in Nigeria. It belongs to the plant family called Sterculiaceae. The fruit is called cocoa pod.

 

Land Preparation

  • Select well-drained deep soil, heavy clay-loam/loam with slightly acidic or neutral pH.
  • Keep the area protected from strong winds.
  • Clear the area manually or mechanically.
  • Avoid clean-clearing. Some forest/big trees may be left to provide shade for seedlings.
  • Leave some plant refuse behind to provide mulch and reduce evaporation.

 

Cultivars or Varieties

Amelonado, Amazon, Criollo Trinitario and hybrids.

  • Amelonado: This produces pods that are lightly furrowed with a round end. The pods are green when unripe and become yellow when ripe.
  • Amazon: This produces pods with long, rough and thick hardwalls. deeply furrowed with a pointed end. The pods are green when mature and become yellow when ripe.
  • Criollo: This produces a high quality bean but the pods are liable to attack by black pod disease.

 

Climatic and soil requirements

  • Cocoa is a humid tropical crop.
  • Grows best in areas with 1140 – 2000 mm annual rainfall, well distributed most of the year.
  • Needs constant supply of moisture.
  • Should be protected from strong winds.
  • Temperature requirement not below 17°C.

 

Method of propagation

  • This is mainly by seeds.
  • Vegetatively by budding and stem cutting.

 

Planting dates: Nursery is done October to January. Field (transplanting) between April and June.

 

Spacing: Nursery: 20cm x 20cm;

 

Field: 3m x 3m.

 

Nursery Practices

  • Loamy soil containing organic matter are used to fill up polythene bags.
  • Seeds are sown in the polythene bag (one seed per bag).
  • Shade is provided to prevent direct heating by the sun.
  • Watering is done twice daily – every morning and evening.
  • Regular weeding is also carried out.
  • Transplanting: Cocoa seedlings are transplanted to the field as from April during the rainy season, i.e five to six months after planting in the nursery. The seedlings are carefully removed from the polythene bag with ball-of-earth earth and are placed in a hole which is about 45cm deep. The hole is covered gently and firmly round the seedling. Some crops like banana and cocoyam are allowed to grow alongside with cocoa seedlings to provide a temporary shade for the cocoa plants.

 

Summary of planting of Cocoa

  • Cocoa trees are usually raised from nurseries.
  • Seeds to be planted in the nurseries must be selected from those freshly harvested pods because seed viability reduces rapidly if kept for long time.
  • Seeds are planted in small baskets filled with good loamy soil and should be well-watered but not water-logged.
  • Keep the baskets with the seeds under shades protected from strong winds.
  • Can use plastic buckets instead of basket though their bases should be cut and sides slit open when transplanting.
  • Transplanting is ready within 5-9 months after sowing the seeds.
  • Planting is usually done at the beginning of the rainy season.
  • Spacing is usually 3m x 3m, though this varies with the cultivar.
  • When transplanting, dig sufficiently deep and large holes to accommodate the whole ball of earth from basket or plastic bucket.
  • After removing the basket/plastic pot, put good loamy soil around the seedling.
  • Apply mulch around the seedling.
  • Water and provide shades.
  • Cocoa seeds may also be planted directly in the field, using initial spacing of Im x 1m, later thinned down to 2m x 2m; and finally 3m.

 

Cultural Practices

  • Weeding: This should be done regularly.
  • Shading: Some crops like banana, cocoyam should be grown to provide shades to cocoa seedlings.
  • Fertilizer application: Urea or sulphate of ammonia is applied at 3000kg/ha when the plant is about 8-12 weeks old on the field.
  • Mulching: This should be done by growing cover crops like calopogonium to cover the soil.
  • Pruning: This is also done by removing the lower branches. Pruning encourages better canopy formation, more light penetration, and improved air movement.

 

Maturity period: Cocoa plant matures within three to five years.

 

Harvesting: Ripe or mature cocoa pod is harvested by carefully cutting off the pod from the tree, using sharp cutlass, harvesting knife or sickle, without damage to the flower cushion.

 

Processing

  • Breaking of pods: The pods are carefully opened with a blunt cutlass or by hitting them with heavy rod to remove the cocoa beans.
  • Fermentation: Cocoa beans can be fermented by using the sweat box or tray method for about five days. During the fermentation process, cocoa beans undergo chemical changes brought about by the action of heat. The beans change to a red brown colour and develop the characteristic chocolate flavour. Theobromine is one of the properties of fermentation. This substance gives cocoa its stimulating property.
  • Drying: After fermentation, the bean seeds are now dried under the sun for 6 -10 days or dryers may be used.
  • Storage: Properly dried beans are stored in sacks or jute bags ready for export.

 

Pests of Cocoa

1) Cocoa capsids: These insects pierce and suck sap from young shoots, causing reduced yield.

Control

  • Spray with insecticides like Gammalin 20 or Didimac 25.

 

2) Mealy bugs: They are vectors or carriers of the virus that cause swollen shoot disease through their biting and sucking of shoots and fruits.

Control

  •  Spray with insecticides, e.g, Gammalin 20.

 

Diseases of Cocoa

1) Black pod disease: It is caused by a fungus (Phytophthora palmivora), which is spread by rain splash. Symptoms include brown spores on fruits covered by soaked, powdery spores which result in rotten black pod.

Control

  • Remove and destroy infected pods.
  • Apply regular weeding.
  • Spray with fungicides, e.g ., Bordeaux mixture or Perenox;
  • Burning of infected pods.

 

2) Swollen Shoot Disease: It is caused by a virus which is transmitted by mealy bugs.

Symptoms: include the swelling of branches, malformation of leaves and premature defoliation.

Control

  • Destroy and burn infected plants.
  • Spray with insecticides to kill the vector (mealy bugs).
  • Plant resistant varieties.

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