Content by Connie Strunk

A corn leaf is shown

SDSU Extension to host corn disease scouting workshop

September 23, 2025

South Dakota State University Extension will host a scouting session for corn diseases confirmed in the state this season.

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.

Coneflower with Aster yellows disease.

Aster Yellows Phytoplasma

Aster yellows is a phytoplasmal disease carried and introduced by aster leafhopper. It is known to infect over 80 different plant families, as the aster leafhopper has extremely broad feeding habits.

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.

Green wheat leaves with yellow streaks throughout.

Wheat Streak Mosaic Virus Complex: Breaking the Green Bridge

As wheat harvest proceeds, it won’t be long until winter wheat planting is underway in South Dakota. To effectively reduce wheat streak mosaic virus, it is important to manage the green bridge effect to slow spread of disease in newly emerging wheat fields.

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.

Three bean leaf beetles. From Left: Brown beetle with black spots on a green leaf. Yellow beetle with black spots on a green leaf. Red beetle with black spots on a green leaf.

Bean Leaf Beetles Showing Up in Soybean

Despite the prediction of low overwintering survival we have observed bean leaf beetles in soybean this week. See our latest observations and management recommendations.

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.

Green wheat plants with some yellowing throughout.

Keep Watch: Wheat Streak Mosaic Virus is Developing in South Dakota Fields

Wheat Streak Mosaic Virus has been reported in South Dakota wheat fields and is also a major wheat disease for Great Plains states in 2025. The virus is sweeping across the state and is rampant in winter wheat.