Common Rust


The common rust fungus attacks corn leaves by producing circular to oblong golden-brown to cinnamon-brown

Common rust in corn

Common rust

Paul Vincelli, University of KY

pustules on upper and lower leaf surfaces. Rust pustules contain a thin membrane that ruptures, exposing the brightly colored spores of the fungus. About mid-season, these pustules turn brownish-black in color. Look for them on middle to upper leaves.


Common rust is caused by Puccinia sorghi. Periods of cool temperatures of 60-72 degrees F (16-23 degrees C) and high relative humidity favor development and spread of this rust species.

IPM Techniques

  • Fields should be examined every four weeks from whorl through dent stage. Scouts should observe two rows of plants 10 feet in length at several representative locations throughout the field. Report severity of the disease according to the following rating scale:

0 = no symptoms

1 = a few pustules on a few leaves of some plants

2 = most leaves on all plants with scattered populated pustules

3 = nearly all leaves of all plants with numerous pustules, some leaves turned brown and withered.

  • Plant resistant hybrids.

References and Additional Information

  • IPM-2 Kentucky IPM Manual for Corn
  • PPA-10a Kentucky Plant Disease Management Guide for Corn and Sorghum, P. Vincelli and D.E. Hershman, Extension Plant Pathology, University of Kentucky

Compendium of Corn Diseases.M.C. Shurtleff. The Amer. Phytopathol. Soc. 1980.

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