Disease Management in Continuous Corn

Managing disease is a key component to growing a successful corn crop, especially in continuous corn situations. A normal corn/soybean crop rotation helps mitigate some of the disease pressure issues associated with continuous corn by breaking up the disease cycle. For different reasons, many farming operations are faced with the need to raise continuous corn to help maximize profitability on a particular acre. It takes a systematic approach to successfully manage against disease pressure in corn on corn. Key components in disease management include residue management, seed bed preparation, planting date, proper fertility, corn product selection, seed treatments, regular field scouting, and fungicide applications (Figure 1).

Disease management in corn production starts with residue management and seedbed preparation. Many corn diseases survive on infected corn residue, so proper residue management can greatly reduce pathogen levels. This helps lower the risk of diseases like Goss's Wilt, Northern Corn Leaf Blight, and others that may be exacerbated by high residue environments. Strong stand establishment and early plant health can help fend off disease pressure. When assessing your seed bed preparation and soil conditions, consider planting your continuous corn acres after your rotated acre corn fields. As the additional residue in corn-on-corn fields slows soil warming and drying and can influence the overall uniformity of soil conditions; thus, the cooler soils slow germination and seedling emergence and development lengthening the period when seedlings are vulnerable to infection by seedling pathogens and insect injury. Delaying planting until soil temperatures are above 55 °F help reduce the risk of poor stand establishment due to seedling disease.¹ Also, using row cleaners to remove residue from the seed row, can help provide a more uniform seed bed temperature.

Proper management of soil fertility can help the corn crop defend itself against diseases and avoid nutrient deficiencies during the growing season. Common nutrient deficiencies seen in corn on corn are nitrogen, sulfur and potassium.

Proper corn product selection is the best proactive defense against common corn fungal diseases such as Northern Corn Leaf Blight, Grey Leaf Spot, Common and Southern Rust and Tar Spot. It really is the only defense beyond residue management for Goss’ Wilt (a bacterial disease). Aggressive scouting and economic applications of fungicides can help manage and defend against fungal diseases. When selecting corn products for continuous corn, strong disease ratings, emergence and vigor scores, stalk strength, and harvest appearance scores should be prioritized.

When managed and scouted aggressively, most of the additional disease pressure associated with continuous corn acres can be either prevented or managed. Therefore, when opting for continuous corn, be sure to have a quality plan in place and be ready to take additional steps to help maximize yield potential on those acres.

Channel Agronomist
Andrew Sikora

Sources

¹Robertson, A. Disease management in corn-following-corn fields. Integrated Crop Management. Iowa State Extension and Outreach. Iowa State University. https://crops.extension.iastate.edu/encyclopedia/disease-management-corn-following-corn-fields#:~:text=Disease%20management%20in%20corn-following-corn%20fields%201%20Hybrid%20selection,...%203%20Planting%20date%20...%204%20Fungicides%20

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