Corn Growth and Development

Additional topics on corn growth and development:

Introduction to Corn Growth and Development:

A key step in high yield corn production is monitoring fields and troubleshooting yield-limiting factors throughout the growing season. Corn growers who understand how the corn plant responds to various cultural practices and environmental conditions at different stages of development are able to use management practices more efficiently and, thus, obtain higher yields and profits. Knowledge of growth and development also helps in troubleshooting problems related to abnormal growth caused by pest problems or inappropriate cultural practices. A helpful resource with information for diagnosing problems related to pests and environmental stresses during the growing season is the Corn, Soybean, Wheat and Alfalfa Guide, Ohio State University Extension Bulletin 827. 

Table 4-3 describes two of the most widely used staging systems for corn development. Extension agronomists use the Leaf Collar Method throughout the United States; crop insurance adjusters, however, use the Horizontal Leaf Method to assess hail and other weather-related plant damage. Table 4-4 shows a timeline relating corn growth and development to normal heat unit (growing degree day) accumulation during the growing season. 

Table 4-3: Growth Staging Systems for Corn. 

Leaf Collar Method 

Start with first oval-shaped leaf as V1. Field defined as being at a given stage when at least 50 percent of plants show collars. 

Horizontal Leaf Method 

Growth staging system used by hail adjusters for hail damage assessment (Table 4-5).

1. Identify uppermost leaf that is 40 to 50 percent exposed and whose tip is below the horizontal. 
2. Typically, a horizontal leaf growth stage will be one to two leaf stages greater than the collar method. 

Table 4-4: A Timeline for Corn Growth and Development. 

*Based on leaf collar method as defined by Abendroth, et al. (2011), Corn Growth and Development, PMR 1009 Iowa State Univ. Extension, Ames, IA. 

**Approximate growing degree days (GDDs) between growth stages and cumulative GDDs since planting according to Nielsen, RL. 2011. Predicting Corn Grain Maturity Dates for Delayed Plantings. Corny News Network, Purdue Extension. [online] kingcorn.org/news/timeless/RStagePrediction. html and Nielsen, R.L. 2016. Grain Fill Stages in Corn. Corny News Network, Purdue Extension. [online] kingcorn.org/news/timeless/GrainFill.html. 

Table 4-5 lists estimated yield loss resulting from varying amounts of leaf area destruction for several stages of development. Although this table was developed to determine yield losses resulting from hail damage, it can also be used to help assess losses resulting from other defoliation injuries (such as wind, frost, insect feeding, herbicide damage, and foliar nitrogen “burn”). The most common damage from hail is loss of leaf area, although stalk breakage and bruising of the stalk and ear may also be severe. Note that the largest yield losses result from defoliation damage that occurs during the late vegetative stages and the reproductive stages (silking and tasseling). Defoliation at early growth stages does not affect yield the same way as it does at later growth stages because much of the plant’s total leaf area is not yet exposed. Extensive defoliation of plants in the 10-leaf growth stage (or V8, eight-leaf collar stage) does not result in a large yield loss because only 25 percent of the leaf area is exposed and the plant can easily recover from early damage. On the other hand, severe damage to plants during tasseling results in a large yield loss because, by that time, 100 percent of the leaf area has been exposed and cannot be replaced. 

Table 4-5: Effect of Corn Leaf Area Loss at Various Growth Stages on Corn Yield*. 

*Adapted from Corn Loss Instructions, NCIS publication No. 6102, Rev. 2013 

**Based on horizontal leaf method for staging plant growth (V/R-stage is shown in parentheses – the horizontal leaf stage is approximately two- leaf stages greater than leaf collar method). 

Early killing frost in the fall may damage immature corn and reduce yield. The effect of frost damage to corn depends on the severity of defoliation, stalk damage, and stage of growth (see Chapter 1, Figure 1-4, for the median fall frost dates). Tables 4-6 and 4-7 provide yield loss and moisture estimates resulting from premature plant death (defoliation) during grainfill. 

Table 4-6: Yield Loss in Corn as a Result of Plant Defoliation at Three Kernel Development Stages. 

Source: Afuakwa, J.J., and R.K. Crookston. 1984. Using the kernel milkline to visually monitor grain maturity in maize. Crop Science 24: 687-691. 

Table 4-7: Whole Plant and Kernel Moisture of Corn at Four Kernel Development Stages.

*Black layer―indicates end of kernel growth and maximum kernel dry weight (physiological maturity).

Source: Afuakwa, J.J., and R.K. Crookston. 1984. Using the kernel milkline to visually monitor grain maturity in maize. Crop Science 24: 687-691.