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Horticultural crops :: Vegetables:: Tomato

Early Blight: Alternaria solani

Field Diagnostic Symptoms

  • Brown spots with concentric rings in a bull's eye pattern with yellow margin.
  • Fruit gets infected through calyx or stem attachment.
  • Brown concentric rings on fruits.
     
Early symptom 
 
Affected plant at advanced stage
 
Concentric ring on Fruits
 
Conidia

Causal organism

  • Alternaria solani

Mycelium :

  • coloured and septate

Pathogen :

  • coloured, beaked conidia with transverse and longitudinal septae, borne singly or in chains

Survival and Mode of Spread

  • Survival: Infected plant debris
  • Primary spread: Infected seed
  • Secondary spread: Conidia carried through rain, wind borne

Favourable conditions

  • Warm, humid (24-29 degree C), rainy and wet weather.

Integrated Disease Management

  • Removal and destruction of crop debris.
  • Crop rotation.
  • Seed treatment: Trichoderma asperellum @ 4g/kg seeds
  • Spray Iprodione 50% WP @ 600 g/ac or Azoxystrobin 23% SC @ 200 ml/ac or Mancozeb 35% SC @ 1 kg/ac or Metiram 70% WG @ 1.0 kg/ac or Pyraclostrobin 20% WG @ 200 g/ac or Zineb 75% WP @ 800 g/ac or Azoxystrobin 18.2%+Difenoconazole 11.4% SC @ 200 ml/ac or Metiram55% + Pyraclostrobin5% WG @ 600 g/ac or Tebuconazole 50% + Trifloxystrobin 25% WG@ 140g/ac

Source of Information

  • https:www.apsnet.org
  • Crop production guide – Horticulture 2020.

Acknowledgement

  • Photo courtesy by Dr.S.Vinodkumar
  • Dr.P.Renukadevi, Professor, Department of Plant Pathology, TNAU, Coimbatore.

Updated on Jun 2023


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