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Prepare for Tar Spot and Protect Your 2023 Corn Harvest

January 24, 2023
untreated tar spot on corn leaf

A corn plant infected with tar spot at the Mt. Joy, PA, Grow More™ Experience site; 2021

Since it was first spotted in the Midwest in 2015, tar spot has become a top concern throughout the Midwest. According to a recent survey of Midwestern corn growers, 71% expressed heightened concern about the disease, with half of all respondents saying they had detected tar spot on their land at least once. Increased rainfall during the 2023 season could lead to substantial yield loss if you’re unprepared.

Tar spot usually appears as raised, circular black spots on corn leaves, stalks and husks. Some other pathogens have similar symptoms, but the University of Minnesota Extension reports that growers can differentiate tar spot by wetting affected parts of plants and rubbing with their fingers. Tar spot will not rub off.

Yield loss, which Purdue University Extension reports can reach 60 bushels per acre in severe tar spot cases, is often caused by reduced photosynthesis. The disease thrives in cool, humid and wet weather, which means states around the Great Lakes typically see higher levels of tar spot. Field irrigation can also increase disease pressure, and the pathogen can overwinter on soil surfaces. According to the survey, 90% of growers who found tar spot in their fields experienced yield loss, making this disease a top concern for the coming year.

Though there is no one-and-done solution for controlling tar spot, fungicide applications can help protect yield potential from diseases like tar spot. For more bushels more often, we recommend Miravis® Neo fungicide for broad-spectrum control of key corn diseases. Powered by Adepidyn® technology, Miravis Neo delivers superior preventive and curative control of diseases including tar spot, gray leaf spot and Northern corn leaf blight. Calculate the ROI potential you could see this season with Miravis Neo by using our revenue calculator.

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Product performance assumes disease presence.

Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.

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