Watch for Early Fungal Disease in Corn and Soybeans

Sponsored by: DuPont Crop Protection

Foliar Health

Wet conditions and moderate temperatures have created the ideal environment for development of crop disease that can reduce yield. 


The earlier a field is infected with disease, the more likely yield will be lost. Scouting crops throughout the season can help you determine if and when a fungicide application is necessary. Use field observations and this decision tree to help with application guidance.

Factors for Disease

Weather conditions are one of the main factors that contribute to disease development. Warm, wet weather can give rise to early season diseases in corn, including Anthracnose leaf blight and eyespot. As the season progresses, high humidity or extended wet weather, coupled with warm temperatures, leads to diseases such as Septoria brown spot and Cercospora leaf blight in soybeans and northern corn leaf blight and gray leaf spot in corn.

Management practices including row spacing, crop rotation and variety choice can impact disease development and progression. Soybean white mold, for example, is more likely in high-yield environments with narrow rows and high plant populations. Fields in continuous production of corn or soybeans are also more vulnerable to disease.

Fungicide Is a Good Investment

Evaluating soybean white mold control, a 2016 University of Wisconsin study showed an 11.5 bushel increase over untreated plots when 9 fluid ounces per acre of DuPont Aproach® fungicide was applied to soybeans at R3. That extra yield could mean increased revenue of more than $122 per acre, based on a $10.61 per bushel soybean price.

The leading yield robbers in corn are early development of gray leaf spot and corn leaf blights. Both diseases are favored by moderate temperatures and wet, humid weather. Northern corn leaf blight can reduce yields by up to 30 percent if lesions are present during or before tasseling and can contribute to stalk rot and late-season lodging.

DuPont Aproach® Prima fungicide has two modes of action and preventive, curative and eradicant activity against gray leaf spot and northern corn leaf blight in corn. A five-year study between 2010 and 2015 showed a revenue of $61.20 per acre when Aproach® Prima was applied to corn versus untreated plots, based on a $3.60 per bushel corn price.

Aproach Prima Graph


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DuPont Aproach® and Aproach® Prima are not registered for use in all states. Contact your local DuPont sales representative for details and availability.

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