Causative agent: Bipolaris oryzae, Helminthosporium oryzae

(Syn: Drechslera oryzae) (Sexual stage: Cochliobolus miyabeanus)

Bengal famine:  1942-1943

Symptoms

• Infected seedlings have small, circular, yellow brown or brown lesions that may girdle the coleoptile and distort primary and secondary leaves.
• Starting at tillering stage, lesions can be observed on the leaves. They are initially small, circular, and dark brown to purple-brown.
• Fully developed lesions are circular to oval with a light brown to gray center, surrounded by a reddish brown margin caused by the toxin produced by the fungi.