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Post Harvest Diseases:: Vegetables:: Tomato

Early Blight: Alternaria solani
  • The fruit become infected-through the calyx or stem attachment, either in the green or ripe stage. Concentric ring present on the fruit surface.
  • Appear leathery and may be covered by a velvety mass of black spores.
  • Infected fruit frequently drop, and losses of 50% of the immature fruit may occur.
  Early blight Black spores Infected tomato

Identification of pathogen:


  • Mycelium- septate, branched, light brown, become darker with age
  • Conidiophores- 50 to 90μm in length and dark coloured
  • Conidia-beaked, muriform, dark coloured and borne singly

Favourable condition:

  • Maximum dispersal of conidia- 9am and 12 noon
  • plants suffering from water stress- susceptible

Spread and survival:

  • Spread by wind and rain splashes
  • Under dry conditions- survives in infected plant debris in the soil for 3 yrs
  • Seed borne


  • Use disease free seeds for sowing
  • Field sanitation
  • Crop rotation with non solanaceous crop
  • Optimum irrigation- to avoid stress condition
  • Seed treatment- thiram 2g/kg
  • 3 sprays with difolatan 0.2 % at fortnightly interval

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

Source of Images:

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