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Agronomic Crops Network

Ohio State University Extension


Staging Corn with Severe Leaf Damage Early in the Season

Staging corn development early in the season is usually fairly straightforward. Starting with the first leaf, which has a short rounded leaf tip (sometimes characterized as the “indicator” leaf), count the number of leaves with visible leaf collars. The collar is the yellow green band that appears at the junction of the leaf blade and leaf sheath.  But what do you do when leaves are not readily evident due to severe plant defoliation caused by hail (like that shown in the picture above, frost, or a combination of factors? In the picture, leaf collars on some plants may be present but it is difficult to discern the upper most collared leaf.

hail injury

You can estimate what leaf stage of development a particular field is at using its planting date and the growing degree days it’s accumulated since planting. University research indicates that from VE to V10 (ten leaf collars), leaf emergence occurs for every 82 to 84 GDDs accumulated (Nielsen, 2008; Abendroth et al., 2011).

The following example (from Nielsen, 2014) shows how to apply this information:

 “A field was planted on April 28, but you do not know exactly when it emerged. Since planting, approximately 785 GDDs have accumulated. If you assume that the crop emerged in about 120 GDDs, then the estimated leaf stage for the crop would be about V8. This estimate is calculated by first subtracting 120 from 785 to account for the estimated thermal time to emergence, then dividing the result (665) by 82 (equal to V8.1).”

Growth-limiting stresses and conditions (soil moisture deficits, nutrient deficiencies, compaction, etc.) affect the accuracy of these predictions (Nielsen, 2014). Nevertheless, this method may be useful in timing when plants reach an approximate stage of growth.


Abendroth, L.J., R.W. Elmore, M.J. Boyer, and S.K. Marlay. 2011. Corn growth and development. PMR 1009. Iowa State University Extension, Ames, Iowa.

Nielsen, R.L. (Bob). 2008. Tips for Staging Corn with Severe Leaf Damage.  Corny News Network, Purdue Univ.  (URL accessed 5/29/2018).

Nielsen, R.L. 2014. Use Thermal Time to Predict Leaf Stage Development in Corn. Corny News Network, Purdue Univ. [On-Line]. Available at (verified 5/29/2018)





Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.