Puccinia sorghi, the causal agent of corn rust, has been known for many years in this hemisphere. For a number of years in the corn belt, the pathogen has subsisted without much indication that it would seriously affect corn. In 1950 the situation changed. Corn rust became epiphytotic. The scope and severity of the disease and the contributing factors became of immediate concern because of the potential threat to the production of the nation's leading crop. If a pathogen such as P. sorghi, hitherto of minor importance, suddenly became a menace to corn production, the patologists in the corn belt would be faced with the responsability of recommending effective control measures. They would be confronted with a dearth of fundamental information concerning control measures and factors influencing corn rust epiphytotics. To present the scope and seriousness of the corn rust problem as it existed in 1950, the plant pathologists in the North Central States were consulted for their observations and opinions pertaining thereto. Their data and opinions are presented and analyzed in the following pages together presented for comparison because in eight of the following reports the 1950 weather conditions were mentioned as being unsually favorable to rust deelopment.

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