Alternaria leaf blight Disease of Wheat

Causal organism-Alternaria triticina. Lowermost leaves are always first to be infected which gradually spread to the upper leaves also. The disease first appears as small, oval, discoloured lesions, irregular in shape as these enlarge and become dark brown to grey. As the disease progresses, several spots convalesce covering large areas resulting in the death or necrosis of leaves.

This disease spreads very fast under warm and humid conditions. Heavily infected fields present a burnt appearance.

Control measures are as follows:

a. Seed borne infection can be controlled by treating seed with Vitavax @ 2.5 g/kg of seed.

b. Apply adequate fertilizers and irrigation.

c. Alternaria leaf blight can also be controlled by Zineb or Dithane M-45. The fungicides may be sprayed as described for rust but mix the urea at 2-3 % with Zineb for first and second sprays.