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Tar spot threatens South Dakota corn yields in 2024

Tar spot threatens South Dakota corn yields in 2024

By Scout Nelson

In recent years, a fungal disease known as tar spot, caused by Phyllachora maydis, has been making its way across the Midwest, now reaching South Dakota. First spotted in the United States in 2015, this disease has been confirmed in several Southeast South Dakota counties, posing a significant risk to corn yields. 

Madalyn Shires, a plant pathologist at South Dakota State University (SDSU), emphasizes that tar spot thrives in warm, humid conditions, typically affecting corn during the mid to late grain fill stages.  Despite its relatively low incidence in the state so far, with minimal lesions observed, the potential for significant yield loss is a concern. The University of Illinois reported losses exceeding 60 bushels per acre in severely infected fields. 

For effective management, Shires advises against immediate panic. The recent severity levels do not justify widespread fungicide application. Instead, she recommends considering corn hybrids with tar spot tolerance, especially for farmers in the affected southeast counties.  

The Tarspotter app serves as a valuable tool for assessing disease risk and determining the need for fungicide treatments. 

SDSU continues to research tar spot, including scouting efforts across all corn-growing counties and investigations into the disease's weedy hosts and genetic diversity.  Collaboration with neighboring states like Kansas and Nebraska is also underway to better understand and combat this emerging threat. 

This situation underscores the importance of proactive management in safeguarding South Dakota's corn production from the growing challenge of tar spot. 

Photo Credit - gettyimages-oticki

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Categories: South Dakota, Crops, Corn

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