Survey has been conducted from Kharif 2008 to Kharif 2014, i.e. continuously for seven kharif seasons to observe natural occurrence of the diseases of rice (Oryza sativa L.) prevailing in North East Alluvial Plains (Koshi Zone) of Bihar in order to assess the recent disease scenario of the region in the changing climatic conditions. During the survey of different locations of seven districts categorized as North East Alluvial Plains viz. Supaul, Araria, Kishanganj, Katihar, Purnea, Madhepura and Saharsa of Bihar state, it has been observed that seven diseases of rice viz. Brown leaf spot, Blast, Bacterial leaf blight, False smut, Sheath Blight and Sheath rot were occurring at varying degree of incidence and causing severe losses to the crop. During survey, it was observed that the incidence of Brown leaf spot of rice was highest (90%) amongst all the districts surveyed whereas incidence of other mentioned diseases were varying in different districts. The incidence of Brown leaf spot was varied in the range from 40 to 90%, Blast (31-75%), Bacterial leaf blight (12-29%), False smut (5-40%), Sheath Blight (12-45%) and Sheath rot (8-32%) during 2008 to 2014 at above-mentioned different districts. The incidence of almost all diseases were highest in Kishanganj district which was followed by Araria and Katihar district. During continuous survey, it had been concluded that Koshi zone as whole was congenial for the development of all important diseases in rice crop.

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