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Identify Rust Early to Protect Corn Yield

June 14, 2017

Every season, rust appears in corn fields throughout the South and, in more recent years, the Midwest. Although rusts don’t survive Midwest winters, pathogens typically travel northward from Southern states each spring and summer.

Common rust does not frequently cause significant yield loss, but according to Purdue University, Southern rust has become more significant in Southern states, routinely reducing yields as much as 25 bu/A on susceptible hybrids that do not receive a fungicide application. In the Midwest, Southern rust has the greatest potential to damage corn fields if it spreads at a critical point in the growing season.

It’s important for growers to be able to identify the difference between these two types of rust in order to best determine whether a treatment plan is necessary.


This agronomic photo shows Southern rust.

Southern rust:

  • Pustules on the upper leaves
  • Orange to light brown and round
  • Densely packed on the leaf surface
  • Can cause significant yield loss in Southern states and has become more problematic in the Midwest

This agronomic photo shows common rust on corn.

Common rust:

  • Pustules on upper and lower leaf surfaces
  • Reddish and elongated
  • Scattered on the leaf surfaces
  • Typically does not lead to significant yield loss

Growers should frequently check the Integrated Pest Management Southern corn rust tracker to stay on top of this disease’s path. If rust spreads to neighboring regions, Syngenta advises growers to treat proactively before rust hits their county.

Syngenta offers Trivapro® fungicide for best-in-class preventive and curative control of rust and other difficult-to-control disease. Trivapro also delivers crop enhancement benefits that help maximize grain fill, produce stronger stalks and reduce lodging.

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