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Maximizing yield potential and minimizing risk are two main goals when selecting corn products. Planting products with different growing degree unit requirements to mid-pollination can help decrease risks of heat and drought stress during pollination. Selecting corn products that can handle the additional stress associated with corn-on-corn environments can be challenging.
Figure 1. Emergence, vigor, disease tolerance, and root and stalk strength are key corn product characteristics to consider, in addition to yield potential.
Generally, the first selection criteria when evaluating corn products is yield potential, followed by various agronomic characteristics (Figure 1). Product performance in plots across multiple locations and years can indicate the consistency and yield potential of a product, and in which environments it tends to excel or falter.
Important agronomic considerations include standability, disease and drought tolerance, insect and herbicide resistance, and good emergence and seedling vigor in cool conditions.
Emergence ratings should be considered when selecting corn products. Commercial products often have very good or excellent vigor and emergence ratings. A strong emergence and vigor rating is especially important if a product will be placed in a no-till or reduced tillage field, or will be planted early, as these management practices can result in cool, wet soil conditions.
Products should be evaluated for tolerance to diseases that are common in your geography. Keep in mind that fungicide applications may mitigate some of the impact associated with a product’s susceptibility to foliar fungal diseases such as gray leaf spot and northern corn leaf blight, although that yield protection comes at a higher cost and risk than product resistance or tolerance.
Stalk and root strength are particularly important for corn that will be planted at a higher population, or for corn that is likely to be under drought stress or any other stress that reduces standability. Stalk diameter decreases with increasing population and drought stress favors stalk rot. If stalk rot appears to be a persistent problem in your system, consider placing more importance on standability and stalk rot resistance in your product selection.
Drydown, stalk quality, and root strength can help manage harvest schedules. Several variables can affect these characteristics such as stresses endured throughout the growing season, untimely frosts, and various pathogens.
A good management practice is to plant a combination of products with early-, mid-, and full-season relative maturities (RM) to help spread out the harvest schedule and help minimize losses from drying costs and lodging. The early RM products can help with getting harvest equipment set properly and fulfilling early fall delivery commitments to elevators. Often, the majority of acres in an operation should be planted to mid- and full-season products due to the tendency for them to have higher yield potential since they have more days to photosynthesize and fill grain. Planting a spread of RMs can help mitigate risks associated with an early fall frost such as low test weight, lower yield potential, and poor drydown.
An often overlooked characteristic when selecting a package of corn products is growing degree unit (GDU) requirements to flowering or mid-pollination. Spreading out GDU requirements to mid-pollination can help decrease the risks of heat and drought stress during pollination.
In addition to yield potential, corn-on-corn systems may have the additional challenge of cooler and wetter soils due to heavy residue. Choosing a product with strong early emergence is important. In geographies where technologies exist, planting products with insect protected trait(s) can help minimize the risk of damage from insects such as northern corn rootworm, western corn rootworm, corn earworm, and European corn borer. Diseases such as gray leaf spot, northern corn leaf blight, southern corn leaf blight, stalk rots, ear rots, seedling blights, and Goss’s wilt are potentially more severe in corn-on-corn production. Though fungicide applications can help effectively manage many of the foliar fungal diseases, selecting corn products with high levels of resistance to these types of diseases is often the best management strategy.
In some cases, continuous corn acres should be rotated among corn products. Many of the pathogens that cause diseases overwinter in crop residue. If one of these diseases occurs on a corn product in one year, inocula will be present in the debris. Therefore, there is a higher risk that the same product will be infected again if it is used in the same field the next year. Rotating to a different product with better ratings for that specific disease can help address this.
Coulter, J. and Van Roekel, R. 2009. Selecting corn hybrids for grain production. University of Minnesota Extension. www.extension.umn.edu. Thomison, P.R. Key steps in corn hybrid selection. AGF-125-95. The Ohio State University Extension. http://ohioline.osu.edu. Elmore, R., Abendroth, L. and Rouse, J. 2006. Choosing corn hybrids. Iowa State University Agronomy Extension. www.agronext.iastate.edu. Web sources verified 9/27/16. 121912010102