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Corn Diseases

All Corn Diseases Content

aerial view of South Dakota farm and surrounding land


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

corn field with sunrise in the background


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.

Three corn cobs with common ear rots. From left: Fusarium ear rot, Gibberella ear and Diplodia ear rot.

Scout for Corn Ear Rots

Several corn fields scouted in northeastern South Dakota counties were found with ear rots. Ear rots were mostly prevalent in areas that experienced hailstorms in the recent past. Ear rots in corn are caused by a few fungal pathogens, and which ear rot develops depends on the weather conditions.

Tan-gray Goss’s bacterial blight lesions were observed in scouted corn fields.

Goss's Bacterial Wilt and Leaf Blight of Corn

Fact sheet for identifying Goss’s bacterial wilt and leaf blight of corn, also known
as bacterial leaf freckles and wilt.

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.

Left: A corn ear showing Gibberella ear rot symptoms. Right: A prematurely dried corn stalk split to reveal pith disintegration due to stalk rot.

Corn Ear Rots and Stalk Rots: The Last Issues To Check for in Corn Before Combining

Before combining corn, it is recommended to scout your field for corn ear rots and stalk rots. It is important to scout corn fields for these two issues in order to make timely decisions on corn combining.

Tan-gray Goss’s bacterial blight lesions were observed in scouted corn fields.

Goss’s Bacterial Wilt and Blight Developing

While out scouting corn fields (the week of August 11, 2020) Goss’s bacterial wilt and blight was found starting to develop in a number of fields.

Green corn plant with abnormal tassel growth.

Crazy Top Disease Developing in Corn

Crazy top disease was observed in a few fields in the Southeast counties in the state. This disease develops in corn that is flooded or under full water saturation when corn has not reached the four-to-five leaf stage.

Three corn diseases. From left: Southern Rust, Bacterial Leaf Streak, and Eyespot.

Southern Rust, Bacterial Leaf Streak, and Eyespot Are Developing in Corn

Southern rust was found in Yankton County, bacterial leaf streak was found in Brule County, and eyespot was found in several fields and counties the week of July 27, 2020.

A mostly green corn leaf that is in brown to yellow markings caused by southern rust.

Is a Fungicide Applied at Tasseling Profitable in Corn?

Corn is currently at tasseling/silking across the state. This is usually the growth stage when a fungicide is applied to control fungal diseases.