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Horticultural crops :: Plantation :: Tea

Blister blight: Exobasidium vexans
Symptoms
  • Small, pinhole-size spots are initially seen on young leaves less than a month old.
  • As the leaves develop, the spots become transparent, larger, and light brown.
  • After about 7 days, the lower leaf surface develops blister-like symptoms, with dark green, water-soaked zones surrounding the blisters.
  • Following release of the fungal spores, the blister becomes white and velvety.
  • Subsequently the blister turns brown, and young infected stems become bent and distorted and may break off or die.

Life cycle

  • The disease cycle repeats continuously during favorable(wet) conditions, and the spores are readily dispersed by wind.
  • Spores that land on a leaf with adequate moisture will germinate and infect it, producing visible symptoms within 10 days.
  • The fungus can directly penetrate the leaf tissue.
  • The basidiospores have a low survival rate under conditions of drought or bright sunlight.
  • The life cycle of the fungus is 3–4 weeks.

 

Blister blight
Management
  • Removal of affected leaves and shoots by pruning and destruction of the same have been recommended.
  • Spraying of Bordeaux mixture or Copper Oxy Chloride 0.1%
  • A mixture of 210g of Copper oxy Chloride + 210g of nickel chloride per ha sprayed at 5 days interval from June to September and October to November
  • Spray Tridemorph at 340 and 560 ml/ha is satisfactory under mild and moderate rainfall conditions

Content validator:
Dr. M. Deivamani, Assistant Professor, Horticulture Research Station, Yercaud-636602.

Image source: Keith, l., Ko, W.H and Sato D.M. 2006. Identification Guide for Diseases of Tea (Camellia sinensis). Plant Disease, 33, pp-1-4.

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