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Fungicide Trial Shows Corn Diseases in Action

September 13, 2019

Corn fungicide trial plot in Slater, IA, on August 13, 2019.

Conditions at our Slater, IA, Grow MoreTM Experience site were cool and wet early in the season, leading to planting delays. Many of the trials were not fully established until early June. Since then, conditions have been on the drier side, which is not ideal for corn diseases.

Our corn fungicide trial displays the impacts of disease and the benefits of timely fungicide applications. Since conditions were dry and diseases like gray leaf spot (GLS) and Northern corn leaf blight (NCLB) thrive in warm, wet conditions, we inoculated our corn with both diseases on June 23. Then we treated the corn with Syngenta and competitive fungicides from June 25 through July 30, at the V4-V8, V15 and R1 growth stages.

Although it was too early to compare yield from each of the fungicide treatments at a recent site event, treated corn appeared healthier while the untreated/inoculated check plants showed clear signs of GLS and NCLB.

Impacts of foliar disease:

  • If left untreated, GLS and NCLB can quickly cover leaves with multiple lesions, diminishing a corn plant’s ability to capture sunlight and photosynthesize.
  • The nutrients the infected plant is able to capture now have to navigate a growing traffic jam of lesions as they travel down the leaves (nutrient highways) on their way into the plant.
  • To compensate for fewer nutrients from the sun, corn plants will rob starches from the stalk to help fill the ear.

These consequences mean fewer available nutrients for growth and grain fill, leading to decreased plant health, increased lodging potential and ultimately lower yield potential.

This agronomic image shows Early signs of gray leaf spot on a corn leaf.

Early signs of gray leaf spot on a corn leaf.

This agronomic image shows gray leaf spot lesions on corn leaves.

As GLS progresses, lesions cover the surface area, reducing a corn plant’s ability to conduct optimal photosynthesis.

This agronomic image shows A build-up of GLS lesions create a traffic jam, disrupting the flow of nutrients down the leaf and into the plant.

A build-up of GLS lesions create a traffic jam, disrupting the flow of nutrients down the leaf and into the plant.

To control GLS and NCLB, we recommend Miravis® Neo or Trivapro® fungicide. Miravis Neo, our latest corn and soybean fungicide, has 3 powerful active ingredients and sets a new standard in its class for broad-spectrum disease control and plant-health benefits. With 2 out of 3 active ingredients providing plant-health benefits, treated corn plants stay healthier longer, resulting in maximum grain fill and yield potential.

Under high or low disease pressure, Trivapro works hard, fighting rust, leaf spots and blights with long-lasting preventive and curative control and plant-health benefits.

To see how the fungicide trial progresses, and for future updates from our Slater Grow More Experience site, sign up to receive our twice-monthly Know More, Grow More Digest e-mail.

All photos are either the property of Syngenta or are used with permission.