Alternaria Leaf Blight

 

Caused by: Fungus

Causal Organism: Alternaria triticina

Symptoms

• Lower most leaves are always the first to show the sign of infection, which gradually spreads to the upper leaves.
• The disease first makes it appearance as small, oval, discolored lesions, irregularly scattered on the leaves.
• The spots became irregular in shape as these enlarge and take up dark brown to grey color.
• As the disease progresses, several spots come closer and cover large leaf areas, eventually resulting I death of the entire leaf.
• A bright yellow marginal zone is sometimes seen around the spots.
• In case of severe attack, leaf sheaths, awns and glumes are also infected.
• Black powdery spores of the fungus cover the lesions at this stage under moist conditions.
• These spores are disseminated by wind and cause disease on healthy leaves and plants.
• The disease spreads very fast under warm and humid conditions.
• Heavily infected fields present a burnt appearance.

Control Measures

• Seed-borne infection can be controlled by treating seed with Vitavax at the rate of 2.5 g per kg seed.
• Apply adequate fertilizers and irrigation.
• Alternaria leaf blight can also be controlled by 0.2 per cent Zineb or Mancozeb 75 WP sprays. It is beneficial to mix urea at the rate of two to three per cent with Zineb at first and second sprays.