Gray leaf spot (GLS) has been a challenge for American corn farmers for nearly 100 years. Illinois was the first state to report GLS back in 1924, and although the disease is still an issue today, there are steps that can be taken to reduce pressure, and ultimately, yield loss.
As one of the most yield-limiting corn diseases in the U.S., scout your fields often to check if GLS is an issue for you. As illustrated in the picture above, Purdue University advises checking corn leaves for small, pinpoint lesions surrounded by yellow halos. As development continues, lesions become long, narrow and rectangular, and can vary from brown to gray in color. Be especially watchful for infection during prolonged warm (75°F to 85°F), humid (more than 90% relative humidity) periods.
To calculate just how much of a yield hit your crop will most likely face, The Ohio State University’s chart below shows estimated percentage yield loss based on ear leaf area affected by GLS at R5 stage.
Estimated corn yield loss based on percentage of infected leaf tissue.
Percentage Ear Leaf Area Affected by Early Dent Stage (R5) | Approximate Yield Loss |
5% or less | 0-2% |
6-25% | 2-10% |
25-75% | 5-20% |
75-100% (leaf death) | 15-50% |
Source: Patrick Lipps, 1998, The Ohio State University. Gray leaf spot and yield losses in susceptible corn hybrids. Crop Observation and Recommendation network. Issue 98-23.
For proactively preventing GLS this season, spray a fungicide application that provides preventive and curative disease control, which will help maximize yield and profit potential.
If you’re seeing areas affected by GLS, plan ahead and select disease tolerant hybrids for those acres next season. Continuous corn and reduced tillage acres are more prone to GLS because the fungus can survive through winter on infected corn residue at the soil surface. In such situations, plant moderate to high GLS-tolerant hybrids as a preventative management strategy.
To find out the GLS tolerance rating of particular Golden Harvest hybrids, enter your location, relative maturity needs or a specific hybrid name in our online product finder.
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