Corn Diseases

All Corn Diseases Content

A green corn leaf with yellow to brown spots throughout.

Corn Disease Update: September 2, 2025

As of September 2, 2025, a number of corn diseases have been reported and confirmed throughout South Dakota. View our latest findings as we approach the fall harvest season.

People stand in a field listening to a person speak

SDSU Extension programs help producers maintain healthy crops

August 26, 2025

Madalyn Shires puts on a lot of miles in the summer. As an assistant professor and SDSU Extension Plant Pathology Specialist, Shires traverses the state visiting research plots and educating crop producers on that research.

Corn

Nearly one out of every three dollars generated by South Dakota agriculture starts in a corn field. Two of every three rows of corn become ethanol.

aerial view of South Dakota farm and surrounding land

Crops

During the growing season, SDSU Extension provides weekly production recommendations.

Corn leaf samples with Southern Rust and Tar Spot.

Corn Diseases in South Dakota Update

Several South Dakota counties have confirmed positive cases of Southern Rust and Tar Spot this growing season. See our latest recommendations for dealing with these diseases before they become a problem.

Corn field with severe wind and hail damage.

Are Fungicides Needed On Hail-Damaged Crops?

Recent storms brought rain, severe wind, and hail. With the hail and wind damage that occurred, many growers are wondering if a fungicide application is needed to protect their hail or wind-damaged crops.

Green corn leaf with yellow rust-colored spots throughout.

Southern Rust Observed in South Dakota Corn Fields

Southern Rust was recently confirmed in South Dakota corn fields. Yield impacts from Southern Rust can be high, so scouting for the disease is highly encouraged to determine if it is present.

Corn leaf with trace amounts of tar spot.

Tar Spot Confirmed in South Dakota

Trace amounts of tar spot were recently found in Yankton and Bon Homme counties and are thought to have originated from corn residue instead of windblown spores. This speaks to the importance of crop rotation in the management of this disease.

Young farmer examining soybean plants n a field at sunset.

Be Aware of Fungicide Resistance in Field Crops

A few soybean and corn fields have received or will be receiving a fungicide application this season. We recommend scouting fields treated with fungicides to determine if diseases are controlled as expected or if there are signs of reduced sensitivity.

SDSU Extension to host tar spot webinar

January 24, 2025

Tar spot is a potentially yield-impacting corn disease that was confirmed in 46 of South Dakota’s 66 counties in 2024. The fungus can cling to crop residue over the winter and re-emerge once temperatures rise. It’s most commonly spread in South Dakota by wind-blown spores.