Corn following corn is often a more stressful environment than corn following soybeans. Continuous corn environments have increased risk of disease, corn rootworm, cooler and wetter soils in spring, and typically require more nitrogen. In addition, each field has its own unique set of circumstances as residue management, disease and insect pressure, and nitrogen strategies differ by field and farming operation.
Selecting hybrids for corn on corn acres requires matching hybrid characteristics to tolerate these types of stress while not sacrificing yield potential. Some seed brands will assign a rating for continuous corn, but Wyffels takes a different approach because a singular rating can’t cover the multiple stress factors discussed above. Each field has its own unique set of circumstances, and you can choose to manage those in different ways. Consider the following when selecting corn hybrids for continuous corn fields.
Emergence and early vigor – Soil covered with heavy corn residue is slow to dry and warm, causing corn to emerge slower than corn planted into soil with less residue. Choosing hybrids with strong early vigor scores is one way to mitigate this risk, but a better approach is to manage residue prior to planting. Residue management can be accomplished by chopping residue in the fall, incorporating residue with tillage, or clearing residue from the seed row with planter attachments or strip tillage.
Plant health – Many of the common corn diseases overwinter on corn residue increasing the risk of infection the following year. A fungicide application at full tassel is great way to manage disease risk. Choosing hybrids with high disease ratings is another way to limit risk. In particular, if Goss wilt was present in a field planned for continuous corn, choose a hybrid with a Goss rating of an 8. Stalk rot diseases can also be more prevalent in continuous corn fields, and hybrids with high stalk strength and staygreen ratings tend to show better late-season plant intactness in continuous corn environments.
Corn rootworm protection – Corn rootworms favor continuous corn systems, and fields in three or more years continuous corn carry more risk than first or second-year corn. Soil insecticides can provide good protection against rootworm but are less effective in dry years. The most consistent protection against rootworm, regardless of weather, is planting hybrids with dual mode of action for rootworm, such as SmartStax.
Nitrogen availability – Soil microbes consume nitrogen (N) as they decompose crop residue. This process, called N immobilization, can create a temporary N shortage in young corn. More N is required to decompose corn residue than soybean residue which is why higher N rates are recommended for corn on corn versus rotated acres. Although hybrids might respond differently to N immobilization the differences aren’t significant enough to justify using hybrid selection as a way to manage the effects of immobilization.
Work with your Wyffels Seed Representative to evaluate the risks for each field and match which hybrid characteristics best mitigate those risks. That will lead to a better continuous corn hybrid decision rather than relying on a single rating.