Early in June, 1909, the yellow-leaf disease (H . gramineum) was prevalent in some fields of barley at Ames. It appeared just before heading of the grain, and destroyed .50 of one per cent of the barley.
This disease was first recorded* at Ames in 1890. It is characterized by longitudinal yellowish-green spots extending in parallel rows upon the leaves and sheaths. The yellowish-green areas are strongly contrasted to the green of the leaves. All the culms of a single stool are affected, and the diseased plants die prematurely. When the spots of the fungus begin to appear the plant ceases to grow and very little barley is produced. This species was referred to Helminthosporium gramineum because it seems to agree with the fungus described by Rabenhorst. It was later found to be somewhat widely disseminated in barley-growing regions. The character of the fungus and its injury to barley were later worked out by several investigators.
Pammel, L. H.; King, Charlotte M.; and Bakke, A. L.
"Two barley blights, with comparison of species of Helminthosporium upon cereals,"
Bulletin: Vol. 10
, Article 1.
Available at: https://lib.dr.iastate.edu/bulletin/vol10/iss116/1