Pythium graminicola was constantly isolated from infected roots of barley grown on the experimental plots of the Northern Iowa Agricultural Experimental Farm, Kanawha, and from plants grown on the plots at the Agronomy Farm at Ames, Iowa, in 1936 to 1939, inclusive.

The symptoms of Pythium graminicola on barley were: Seed decay, seedling blight, root necrosis, yellowing and curling of leaves and stunting. Pythium root necrosis was very severe in 1936 and in 1938. The injury to the seedlings was greater at high temperature than at low. The pathogen grew very slowly at 15° c., which may in part explain the larger yields incident to early seedings.