Thursday 8 November 2012

Citrus diseases and their control.

Citrus diseases and their control.

By: Muhammad Imran Khan
               Citrus is the number one fruit in Pakistan as for as it production is concerned.  It is grown in many districts of Pakistan. Sargodha is number one of them. It is exported to many countries mainly Australia, UAE, EU, china, Saudi Arabia, Russia and others. Some of the fruit is rejected for export due to its diseases and pesticidal residues. The diseases cause loss of farmer because they lower the per acre production and secondly market value is also greatly reduced .diseased plants cannot bear good fruit and fruit drop is also caused. Weak plants need great care and protection. The use of good cultural practices can be helpful for controlling diseases and making the plants grow vigorously. Over irrigation and absence pf proper drainage system in monsoon is a big reason for the attack of various diseases. Nutrients deficiency is also not properly handled. Mix cropping or growing other crops in citrus orchards is also common practice of our farmers which should also be avoided. Because different crops are carrying different insects pests and pathogens with them. After the harvest of that crop those insect pests and pathogens migrate to the citrus plants. There is no or very less concept of wind breaks. Windbreaks are very important because they control the pollination process flower and fruit drop. The important citrus diseases are following.
FUNGAL DISEASES
(i) Bark Splitting / Gumosis Disease
  • Attack at the branches and trunk
  • Vertical cracks on the bark 
  • Greasy/water soaked look 
  • Release of gum like exudation 
Control 
  • Paste of fungicide (1 part) in lime (20 parts) with sufficient water to make a workable paste
  • By avoiding the injury to the plants 
(ii) Damping Off (Rhizoctonia Solanai)
  • Damping of seedling before or after emergence 
  • At the nursery stage 
  • Many toppled seedlings 
Control 
  • Use un-infested soil 
  • Disinfect with fumigents 
BACTERIAL DISEASES
(i ) Citrus  canker

  • Yellowish spots on leaves, twigs, petiols and branches
  • Small and enlarged lesions 

Control

  • Prune and burn the affected plant parts 
  • Spray the Bordeaux mixture and avoid jutti khatti  as windbreak
  • Apply Bordeaux paste on the stem
 (ii) Citrus Decline

  • Pathological (Root rot nematode, Bark splitting, Virus disease etc.) 
  • Nutritional  disorder
  • Poor cultural practices 
  • Poor selection of the rootstock 
  • Bad aeration of the roots  
Control

  • Control of the disease will be site specific according to the cause of the disease.
VIRAL DISEASES

(i) Citrus Tristeza Virus (CTV)

  • The most destructive disease 

Control

  • No specific control found yet
  • Use disease free rootstock

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