One of the most important decisions you make as a corn producer each year is the selection of corn products for planting. Corn product selection is a critical component for achieving high yields.
Yield Potential. Selecting a product for yield potential sets the bar high for the coming year. Product performance in plots across multiple locations and years in a region can indicate the consistency and yield potential of a product. Yield stability over multiple trials with differing growing conditions is critical, since we cannot predict the next growing season’s conditions.
Maturity. Maturity is one of the most important factors to consider when selecting corn products. Indentify an acceptable maturity range based on the number of growing degree units (GDUs) required for a product to reach physiological maturity (black layer). Selected corn products should reach maturity one to two weeks before the first average frost (32° F) to allow time for grain to dry-down and provide a buffer against a cool year or late planting. Spreading out GDU requirements to mid-pollination can help decrease risks of heat and drought stress during pollination.
Planting a range of product maturities can help reduce damage from diseases and environmental stress at different growth stages, as well as spread out harvest time and workload. A good management practice is to plant a package of products with a combination of early-, mid-, and full-season relative maturities (RM). A majority of acres in an operation should usually be planted to mid– and full-season products due to a higher yield potential since they have more days to photosynthesize and fill grain. However, later relative maturity (RM) products will typically have higher harvest moisture. On average, grain moisture at harvest increases by 0.25% to 0.44% with each one day increase in RM.1 Having a spread in RM can also help mitigate risks associated with an early fall frost, such as low test weight, lower yield potential, and slow dry-down. Selecting products of appropriate maturity is important for a balance between yield potential and moisture at harvest.
Agronomic Traits. Choosing a product with a strong balance of agronomic traits is important for managing risk (Figure 1). The relative importance of individual traits differs with production practices and growing conditions. Important agronomic considerations include standability, disease and drought tolerance, insect and herbicide resistance, and good emergence in cool conditions.
Figure 1. Emergence, vigor, disease tolerance, root and stalk strength are key corn product characteristics to consider, in addition to yield potential.
Standability is a common agronomic trait that is critical for ensuring the grain produced is harvestable. Stalk and root strength is particularly important for corn that will be planted at a higher population, or for corn that is likely to be under drought stress. Stalk diameter decreases with increasing population. Any stress that reeuces photosynthesis, such as drought, 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.
Emergence should also be considered when selecting corn products. Early planting is important for high yield potential, but soil in the early spring is often cool and wet, causing many stresses on young seedlings. This makes strong emergence a key agronomic trait (Figure 2).
It is important to learn how to identify the major corn diseases in your area and select corn products with specific resistance to these diseases.
Figure 2. Strong emergence can be particularly important when planting early in cool soils.
Corn-on-Corn Acres. Selecting corn products that can handle the additional stress associated with corn-on-corn environments can be challenging. Regardless of the environment, the first selection criteria should be 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. Where applicable, 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 (GLS), Northern corn leaf blight (NCLB), Southern corn leaf blight (SCLB), stalk rots, ear rots, seedling blights, and in some areas, Goss’s wilt, are potentially more severe in corn-on-corn. 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 a good management strategy corn corn-on-corn acres.
In some cases, continuous corn acres should be rotated among corn products. Pathogens that cause diseases may overwinter in the soil and crop residue. If a disease occurs on a corn product in one year, inocula may be present in the soil and debris. Therefore, there is a higher risk that 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 issue.
Corn products should be selected and placed using as much information as possible. However, a product’s performance will vary based on the year and environment. Selecting a package of three to five corn products is important to help reduce uncontrollable risks.
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 7/21/15. 121912010102