Amaranthus is one of the most important leafy vegetable consumed and cultivated in Southern India. Amaranthus (Amaranthus tricolor L.), widely knownas the ‘poor man’s spinach’ is one of the cheapest, most accepted and commercially cultivated leafy vegetable. Among the different diseases affecting amaranth, the leaf blight caused by Rhizoctonia solani Kuhnis known to be the most devastating disease threatening the cultivation of this plant seen especially after monsoon rains. The disease is characterised by light cream colored spots on the foliage which rapidly spreads causing extensive damage leading to destruction of crop and thus heavy economic loss to the farmers. On the underneath surface of the infected leaves, white powdery masses of basidiospores of the telemorph of the causative fungus. The humid weather conditions in Southern India make the disease serious constraint for amaranth cultivation.The chemical control of the disease through the use of fungicides, which could cause serious health hazards.