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All About Timing When It Comes to Corn Fungicides

November 12, 2021
Foliar fungicides

Foliar fungicides applied during R1 provide better protection against corn diseases.

Timing is crucial when it comes to applying fungicides to your corn crop. Apply too early, and your corn can be left vulnerable to disease late in the season, impacting your yields. Apply too late, and your corn can be equally susceptible to disease. Worse still, using the wrong fungicide at the wrong time can negatively impact corn’s health, leaving it more susceptible to disease, and provide little disease protection, a double whammy.

All About Timing

University of Kentucky research indicates corn fungicides applied during tasseling or early silking stages of development provide optimal disease control and yield response. An economic benefit is less when fungicides are applied too early or too late – i.e., after “brown silk.”

Recently, some competitors have recommended applying in-furrow corn fungicide treatments for season-long disease protection, so we put the recommendation to the test at our Grow More™ Experience site in Janesville, MN.

When put to the test, corn plots treated with an in-furrow application of Xyway™ LFR® fungicide fell prey to Northern corn leaf blight (NCLB). After a long and dry summer, much of the crop had experienced this. There were also issues with stand and emergence, with 10% delayed. Both of these issues caused a reduction in plant health and, as a result, a reduction in corn yield.

Northern corn leaf blight on a corn leaf in Janesville, MN

Northern corn leaf blight on a corn leaf in Janesville, MN.

Comparatively, corn plots treated with an application of Miravis® Neo fungicide during the R1 stage saw healthy green leaves and no NCLB, even after summer-long drought conditions.

Another corn fungicide watch out? Adjuvant pairings

At the same Grow More Experience site in Janesville, MN, we also tested corn fungicide application timing and using the right adjuvants.

When applying fungicides that contain Nonylphenol Ethoxylates (NPEs) during the R1 stage, corn plants are more likely to experience arrested ear development. Using adjuvants with fungicides is generally beneficial because they can help with deposition, increase coverage and maximize performance. But again, it is all about the timing and using the right pairing (adjuvant + fungicide). If a fungicide that contains NPEs is applied during the critical developmental stages (V5-R1), then it can cause damage to the plant’s health. However, if you use a fungicide without an NPE, the fungicide can shield your corn from diseases without the adverse effects.

arrested ear syndrome

Arrested ear development caused by pairing a corn fungicide with the wrong adjuvant.

To get the most disease protection for your corn crop, we recommend applying Miravis Neo fungicide during the R1 stage. The three-modes-of action fungicide offers great protection during the most important developmental stages and continuously helps deliver nutrients late in the season to maximize your corn’s health and yield.

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