Tar spot infection can easily cause 30 to 40 bu/A in yield loss in corn¹.

Between unpredictable weather and disease pressure, 2019 was certainly not an easy year for many growers. Excessive rain and high humidity in regions of the Midwest created prime environmental conditions for disease development, resulting in sightings of the usual yield-robbing culprits in your corn and soybean fields. Here’s a look back at the top diseases from 2019 that could overwinter and resurface again in 2020.

Corn Yield Thieves

• Tar spot
  • Tar spot became a bigger threat this season with increased severity and movement into new states like MN.
• Northern corn leaf blight
  • Northern corn leaf blight caused damage to many fields in 2019, and since the pathogen that causes it overwinters in soil and crop residue, it can reemerge next season.
• Gray leaf spot
  • Very common in parts of the Midwest, gray leaf spot severity and abundancy has increased in states like Indiana.

Soybean Trespassers

• White mold
  • White mold was especially widespread this year with reports from many Midwestern states including MN, ND and SD.
• Brown spot
  • Brown spot can spread by rain splashing from old soybean debris to the growing plants. As a result, it was very common since there was frequent, heavy rainfall throughout the 2019 spring and summer.
• Frogeye leaf spot
  • Since the fungus that causes frogeye leaf spot lives in infected crop debris, this disease has become increasingly common with sightings in IA, NE and SD.

Overall, if you didn’t apply a fungicide you likely saw increased disease pressure this season. Even if you did apply a fungicide, you could still be at risk next season because many of these key disease pathogens can survive for years, waiting for ideal infection conditions.

The best way to prepare for disease pressure is to plan on applying a preventive and curative product in 2020 like Miravis® Neo fungicide. It provides unmistakably superior disease control in both corn and soybeans, and it has added plant-health benefits that keep crops visibly healthier longer.

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¹CornPro 3.4 Iowa State University.