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Agricultural crops :: Cash crops :: Tobacco

Powdery Mildew: Erisiphe cichoracearum var nicotiane

Symptoms
  • Initially greyish white spots (about 0.5-lcm in diameter) appear at the base of the lower leaves of the maturing plant.
  • Under favourable conditions of low temperatures (16° -23° C) and high humidity these white patches spread to upper leaves, enlarge and cover the entire surface of the leaf.
  • Such leaves on curing get scorched and show brown patches rendering them unfit for marketing.
  • Sometimes leaves with incipient infection result in blemished on curing which reduce the commercial value of leaves.
Powdery mildew symptoms in the field A tobacco leaf covered with powdery mildew Progress from lower to upper leaves

 


Management
  • Avoiding over fertilizing, overcrowding of plants and removal of affected basal leaves will help in minimizing primary infection and spread of the disease.
  • Early planting to escape cool temperature prevalent at the maturing stage will also reduce the incidence.
  • Apply sulphur powder (200 mesh) @ 40 kg/ha to soil between plant row 6-8 weeks after planting. Mix ash or sand to sulphur for easy application.
  • See that sulphur does not fall on tobacco leaves. Recommended for black soils only.
  • Spray 0.2% Karathane or Thiovit or 0.05% Carbendazim just before the disease sets in Repeat at 10-12 days interval if necessary
  • Use resistant varieties like Swarna or Line 2359 developed at Central Tobacco Research Institute, in disease endemic area.

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