Frog Eye spot of Tobacco

 Frog Eye Spot: Cercospora nicotianae

  • Small, pale to brown, round or irregular spots measuring 0.5 – 3 mm in diameter and cracked centers appear on the affected leaves of the plant.
  • Affected leaves become dry and fall off.
  • The disease may cause cankers on the stem.
  • The infection spreads to the bolls and finally fall off.
  • During frequent rains, large necrotic areas appear which destroy much of the leaf. During hot dry weather, frog eye-spot may be only pinpoint in size.
  • In flue-cured tobacco the same pathogen causing infection at the harvesting time when cured results in innumerable, small, uniform, dark-brown to black spots popularly known as ‘Barnspots’ which affect the market value of the leaf.
  • The nurseries should be located away from barns and all the diseased debris removed promptly and destroyed.
  • Avoiding excess nitrogen fertilization and picking over ripened leaves also helps in minimizing leaf spotting.
  • Fungicidal sprays with Bordeaux mixture 0.4% (4g/lit), Zineb 0.2% (2 g/lit) or 0.1% (1g/lit) Benomyl as per the schedule suggested under damping-off has checked leaf spotting in the seedbeds.
  • In the field, removal of sand leaves immediately after the transplants have established, and weekly application of 0.4% (4g/lit) Bordeaux mixture or 0.1% (1g/lit) Benomyl or Thiophanate methyl or 0.03% (0.3g/lit) 5-6 weeks after planting has given adequate control of frog-eye spot.



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