ORANGE (Citrus sinensis)
AGRICULTURAL SCIENCE

ORANGE (Citrus sinensis)

Orange is a fruit crop which belongs to the citrus family. The fruit of orange called berry is succulent, fleshy and juicy and it is rich in vitamins and minerals.

 

Land Preparation: The land is cleared with cutlass and stumping is done. The land is then ploughed and harrowed mechanically.

 

Varieties/Cultivars: Varieties of the Citrus spp. or family include:

  • Sweet Orange – Citrus sinensis.
  • Sour Orange – Citrus aurantium.
  • Lime – Citrus aurantifolia.
  • Lemon – Citrus limon.
  • Tangerine – Citrus reticulata.
  • Grape fruit – Citrus paradisi.
  • Shaddock (Pomelo) – Citrus grandis.
  • King orange – Citrus nobilis.

 

Climatic and soil requirements: Sweet orange requires a temperature of 25°C – 35°C, rainfall of 75cm -125cm per annum and a well-drained fertile and deep soil. It also requires a higher elevation and slightly sloping land.

 

Planting materials

  • Seeds.
  • Budded seedlings.
  • Grafted seedlings.

 

Method of propagation: Sexually (by seeds) and vegetative propagation, e.g, budding.

 

Planting date

  • Pre-nursery is ideal between October and December.
  • Nursery in April and May.
  • Budding is done a year later.

 

Spacing

  • Pre-nursery is 3cm x 3cm.
  • Nursery is 60cm x 60cm.
  • Field is 7.0m x 7.0m.

 

Nursery Practices

Pre-nursery:

  • The seeds are raised in seed trays by October – December ina loamy soil, rich in organic matter.
  • The seeds are sown 3cm x 3cm at 2cm deep.

Nursery:

  • The seedlings are now replanted at 60cm x 60cm spacing.
  • It is planted around April and May.
  • Watering, weeding and shading are provided.
  • Budding and grafting are done a year later.

Transplanting: After one year of budding, the seedlings are transplanted to the field at a spacing of 7.0m x 7.0m.

 

Cultural Practices

  • Weeding: This is done regularly by cutlassing or by herbicides.
  • Fertilizer application: Sulphate of ammonium at the rate of 350kg/ha is applied by ring method at regular intervals.
  • Mulching is also done during dry season.
  • Irrigation, especially during dry season, is also practised.
  • Pruning can also be done.
  • Insects and diseases should be controlled and prevented.

 

Maturity Period: This occurs between three and seven years.

 

Harvesting: Clean or spot-picking of matured or ripe fruits with hand or harvesting knife is done carefully and over a period of time.

 

Processing and storage: Orange can be processed into orange juice which can be stored in canned or bottled form.

 

Pests of Orange

1) Thrips.

2) Red Mites.

3) Scale insects.

4) Aphids.

5) Fruit borers.

6) Caterpillars.

All these pests attack citrus leaves, flowers and fruits.

Control

  • Spray with insecticides like Gammalin 20 and Malathion.

 

7) Leafhoppers: These attack citrus leaves, leading to defoliation and reduced yield.

Control

  • By handpicking.
  • Use poison baits

 

Diseases of Orange

1) Gummosis: It is caused by a fungus Phytophthora spp which is spread by air and through the soil. Symptoms of the disease include rottening of the bark near the ground, drying and cracking of bark, release (exude) of gum or slimy substance and leaves turn yellow and begin to die back.

Control

  • Use resistant varieties.
  • Spray with appropriate fungicides.
  • Paint the trunk with crude cabolic and water.

 

2) Tristeza: It is a viral disease transmitted by aphid.

Symptoms include phloem necrosis and swelling at bud union.

Control

  • Use resistant varieties.

 

3) Citrus Scab: It is a fungal disease (Sphaceloma faucett) which spreads within the soil. It attacks young leaves and stem, especially in nursery stage.

Control

  • Treat with fungicide, e.g, Bordeaux mixture.

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