Wheat Smut

Description and Importance:

  • Smut mean sooty (black) or charcoal like powder
  • Responsible for heavy losses when susceptible varieties with infected seeds are grown year after year
  • Cause losses 3-30 %

Etiology:

Causal organism: Ustilago tritici

Order: Ustilaginales

Family: Ustilaginaceae

Symptoms:

  • Head of affected plants converted into black mass of spores & no grain formation
  • Affected young spike lets covered by silvery membrane
  • Only the awns of awned varieties escape transformation
  • Spores easily separate & blown off by wind leaving bear rachis

Disease cycle:

  • Air dried spores can survive for 12 months at 0-10 c
  • Pathogen is internally seed-borne
  • Infection occur when flowers are in full bloom & ovary is just developed after fertilization

Epidemiology:

  • Temp 22-25 °C
  • RH 60-85 %

Management:

  • Solar energy treatment: Presoaking period of 4 hrs followed by 1 hr exposure to sun in summer
  • Hot water treatment: 4-5 hrs in a tub at ordinary temp, at 132 F for 5 min & 132 F for 7 min
  • Seed treatment with Vitavax & Baviston @ 2.5-3g/kg are systemic fungicides & effective
  • Resistant varieties (Perwaz, Watan, Sehar, Shafaq)

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