Continuous Corn Disease Management

September 24, 2023

Despite a corn producer’s best efforts, disease can limit yield potential. Disease in the corn crop is a potential, regardless of the producer, the environment, or the year. In 2022, disease reduced corn bushels by 2.8 percent across the United States. This is down from the overall values from each of the previous five years, which were 6.5, 3.9, 6.8, 10.9, and 6.7 percent for 2021, 2020, 2019, 2018, and 2017, respectively.¹

When considering planting continuous corn, disease development should be a major consideration. Some management decisions that can help minimize disease development and impact include:

Residue management
- A buildup of corn residue can reduce soil temperatures, slow soil temperature warm up, retard soil moisture loss for field work, and in some cases create an environment where specific diseases can thrive. A good practice is to scout the previous year’s corn field to determine what diseases were prevalent, as disease pathogens may over-winter in the residue and cause issues the following year. Burying infested residue by way of tillage can help reduce the potential for disease development. Tillage can also help improve soil temperature and reduce soil moisture which can create a conducive environment for early season diseases.
Corn product selection
- Selecting a corn product that is well adapted to known disease pressures is one of the most important and easiest decisions a grower can make. When selecting products, they should be selected with strong ratings for emergence, seedling vigor, disease resistance, and root and stalk strength. Strong emergence and vigor characteristics help promote emergence through heavy residue and cool, wet soils. As mentioned earlier, the previous year’s residue can harbor disease pathogens. Choosing a corn product that has good resistance to northern corn leaf blight, gray leaf spot, tar spot, Goss’s wilt, and other diseases should help in a continuous corn scenario.
Seed treatment
- There are several fungal pathogens that inhabit the soil and carry over in residue. Fungal species in several genera (Fusarium spp., Rhizoctonia spp., Pythium spp., Diplodia spp., Penicillium spp., and Trichoderma spp.) can cause seed rots and seedling blights in corn.² Fungi in the soil are quite common, but in continuous corn fields, those pathogens have a large supply of residue to survive on. This increases the chance for a higher pathogen load and for diseases to occur. Using a good fungicidal seed treatment helps protect the seedlings from soil born disease potential.
Fungicide preparation
- With the increased chance of infection in continuous corn, in-season scouting and decisions on foliar fungicides based on corn product susceptibility, environmental conditions, and presence of foliar fungal diseases should be a foucus. Lining up the proper fungicide product and the method of application should be considered well before “fungicide season” approaches. Consider researching fungicide effectiveness on certain diseases and their level of disease control. It should be the goal to protect the ear leaf and leaves above the ear leaf to help maintain plant health through the grain fill period.

Lauren Botine
Channel Agronomist

Sources
¹Mueller, D., Wise, K., and Sisson, A. 2023. Corn disease loss estimates from the United States and Ontario, Canada — 2022. Crop Protection Network. https://cropprotectionnetwork.org/publications/corn-disease-loss-estimates-from-the-united-states-and-ontario-canada-2022#:~:text=In%202022%2C%20disease%20reduced%20corn%20bushels%20by%202.8,for%202021%2C%202020%2C%202019%2C%202018%2C%20and%202017%2C%20respectively.

²Robertson, A. and Munkvold, G. Potential disease problems in corn following corn. Integrated Crop Management. Iowa State University. https://crops.extension.iastate.edu/encyclopedia/potential-disease-problems-corn-following-corn.

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