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Corn Stand Evaluation and Replant Considerations in Indiana

 

Corn Stand Evaluation and Replant Considerations in Indiana

Corn Stand Evaluation and Replant Considerations in Indiana

Many different stress factors are capable of reducing corn stands, such as:

  • cold or wet soils
  • insect feeding
  • unfavorable weather conditions
Start by assessing the density and health of the current stand.

Stand Counts

  • Take several sample counts to represent the field.
  • Sample a length of row equal to 1/1000th of an acre.
  • Measure off the distance appropriate for your row width, count the number of live plants and multiply by 1000 to obtain an estimate of plants/acre.
Corn stand evaluation chart
  • In situations such as flooding damage, only a portion of the field may need to be considered for replant.
  • Frost or hail can damage a wide area. In this case plant density and health should be assessed across the entire field.
  • When an injury event such as frost or hail occurs it is best to wait a few days to perform a stand assessment, as it will allow a better determination of whether or not plants will recover.
Evaluating stand count in corn field
Growth of green tissue near the growing point indicates that this plant would have recovered.

Growth of green tissue near the growing point indicates that this plant would have recovered.

Growth of green tissue near the growing point indicates that this plant would have recovered.

Soft translucent tissue near the growing point indicates that this plant will not recover.

Stand counts should be taken randomly across the entire area of a field being considered for replant; this may include the entire field or a limited area where damage occurred.

After a plant stand has been assessed it is important to consider other factors such as:

  • Is the stand consistent, are large gaps present.
  • Will the stand have adequate crop canopy to assist with weed control and irrigation efficiencies.
  • Will replanting provide an economic gain.
  • Are the remaining plants healthy and relatively equal in maturity.

Replant Yield Potential

  • The expected yield from the current stand should be compared to expected replant yield.

Table 1. Yield potential for a range of planting dates and final plant populations. (Source: Emerson Nafziger, Eric Adee, and Lyle Paul, Univ. of Illinois.)

Yield potential for a range of planting dates and final plant populations.

Other Factors to Evaluate

  • Stand uniformity - An uneven stand will yield less than a relatively even stand with the same number of plants.
  • Plant health - Plants that are severely injured or defoliated will have reduced photosynthetic capability and a lower yield potential.

Corn yield is influenced by stand density as well as stand uniformity.

  • Variation in plant size can have a negative impact on yield.
  • Plants with delayed emergence or development are at a competitive disadvantage with larger plants in the stand and will have reduced leaf area, biomass, and yield
Yield potential for a range of planting dates and final plant populations.

Figure 1. Yield potential of delayed and uneven corn stands.

Maturity Selection for Delayed Planting

  • A frequent question pertaining to replanting corn is how full season of a hybrid can be planted and still reach physiological maturity.
  • When considering which hybrid to replant, consider GDU accumulation between the planting date and average first frost date and hybrid GDU requirements to reach physiological maturity.
  • Research has shown that corn can adjust its growth and development, requiring fewer growing degree units (GDU’s) to reach maturity when planted late. Late-planted corn showed a reduction in GDU requirements of about six GDU per day of planting delay.
Earliest, latest, and average dates of first fall frost  in several Indiana locations.

Figure 2. Earliest, latest, and average dates of first fall frost (< 32º F) in several Indiana locations. (Source: Midwest Regional Climate Center)

Dates at which there is a 50% probability of an autumn freeze of 32 F or less.

Figure 3. Dates at which there is a 50% probability of an autumn freeze of 32 F or less. (Source: USDA-NASS)

Table 2. Average accumulated GDUs between planting dates and average first frost date for several locations in Indiana.

Dates at which there is a 50% probability of an autumn freeze of 32 F or less.

Author: Mark Jeschke

May 2017

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The foregoing is provided for informational use only. Please contact your authorized Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.