Leaf or Brown Rust of Wheat

Leaf (Brown) Rust of Wheat:

Description:

  • Most prevalent*(found frequent occurrence) where dews are common
  • Disease severity increases prior to heading
  • Early infection results in weak plants, poor roots & tiller formation.
  • Appears in February after yellow rust.
  • Leaf rust causes damage by reducing number of kernels per head and kernel size.

Importance:

  • Cause losses up to 50% in severe cases.
  • Estimated losses over $350 million in USA alone.

Etiology:

Causal organism: Puccinia recondita f.s.p. tritici

Order: Uredinales

Family: Puccinaceae

Symptoms:

  • Pustules have uredia that develop as points of bright orange color on leaves.
  • Spots are rare on sheath & stalk.
  • These pustule are bigger in size than of yellow rust, scattered irregularly.
  • Infected plants take longer time to produce mature ears*(grain bearing part).
  • Rust pustules can be distinguished from other leaf spot diseases by rubbing finger on leaf surface.

Disease cycle:

  • Uredia*(sac like structure that bears urediniospores) over seasons on volunteer plants.
  • Alternate host Thallactrum flavum (bushy plant) also harbors fungal spores.
  • Aeciospores from alternate host dispersed by wind.

Epidemiology:

  • Free water on leaf & 18.3-23.9°C favors the spore germination.

Management:

  • Destruction of alternate host.
  • Use fungicides i.e. carbendazim, propiconazole, difenoconazole.
  • Sow resistant varieties i.e. Anaj 2017 and Akbar 2019.

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