Content by Connie Tande

External and internal ring rot symptoms on two potato samples.

Bacterial Ring Rot: Yet another devastating disease of potato

Ring rot is primarily a disease of stored tubers and seed potatoes, where it produces black or brown lines just below the surface of the potato.

Two broccoli plants exhibiting early black rot symptoms.

Black Rot of Brassica Crops

Black rot is an uncommon, but devastating bacterial disease in South Dakota that can develop during extended periods of hot and wet weather, leading to rapid and widespread crop loss.

Dried corn growing in a field with visible damage and molding.

Mycotoxins: Should you be concerned?

Environmental stress caused by the weather or damaged crops increases the potential for mold and mycotoxin development. Learn some answers to common questions about mycotoxins and how to manage them.

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 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 leafhopper resting on a corn leaf.

Corn Stunt in South Dakota

In late September, a sample received from Deuel County was confirmed positive for corn stunt, a disease spread through corn leafhopper feeding. This diagnosis is the furthest north corn stunt has ever been confirmed and reported in the United States.

Top: Field pennycress leaves and seeds. Bottom: Shepherd’s purse leaves and seeds.

Early Season Prevalence of Field Pennycress and Shepherd’s Purse

Many fields that are planted to winter wheat or have yet to be tilled may have a healthy infestation of field pennycress or shepherd’s purse. Learn some expert tips for identifying and managing these weeds before they become a problem this growing season.

Head of garlic with discoloration due to Embellisia Skin Blotch.

Embellisia Skin Blotch of Garlic

Have you noticed irregular, dark areas on the outer scales of your garlic bulbs? It's possible it might have Embellisia skin blotch, a fungal disease that can develop during periods of high summer moisture.

Wheat leaf showing the green and yellow mosaic streaking associated with WSMV.

Wheat Streak Mosaic Virus Showing Up in Fields

Wheat streak mosaic virus is a viral disease, which has been found in samples recently sent into the SDSU Plant Diagnostic Clinic. Learn how to identify it before it takes a toll on wheat crops.