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Evaluating Corn Stands (05/28/15)

Corn planting, even with the recent rainy weather related pause, is well ahead of average. The warmer weather of the past few days has really helped corn growth and corn in most fields have emerged.

Evaluating Corn Stands

Corn planting, even with the recent rainy weather related pause, is well ahead of average. The warmer weather of the past few days has really helped corn growth and corn in most fields have emerged. Given the lateness of the season with regards to the optimum planting date of corn, evaluating corn stands should be given priority if a decision on replanting might be needed. There have been a number of challenges impacting corn emergence this season including uneven soil moisture (early planted fields), excessive moisture (more recently planted fields), cold soils and a hard frost. Estimate your plant population by counting the number of emerged plants in a thousandth of an acre (17’ 5” and 23’ 10” row lengths for 30 inch and 22 inch row spacing, respectively) in about 20 places in your field and then multiple the average of those counts by 1,000.  Use Table 1 to estimate the likely yield of your current crop and your likely yield if you replant. These data indicate that even a half stand planted early will likely be more productive than a full stand planted after the June 1st. Of course uniformity of the field and uniformity of emergence can also be factors to consider when looking at the potential productivity of your field and the need for replanting.

plsc.ransom.table 1

Information in this table is adapted from data obtained for the northern zone of Wisconsin (70-95 RM zone). See http://corn.agronomy.wisc.edu/Pubs/UWEX/A3353.pdf by J. Lauer for the full report. The May 1st column in this table assumes that a full season hybrid is used.  All other columns assume that an earlier maturing hybrid is grown. 

 

If you determine that replanting is required, chose a hybrid that is earlier than the “full-season” hybrids recommended for your area of the state (see Table 2).  You may give up some yield potential, but an earlier hybrid will help minimize the risks associated with the crop being damaged by frost before maturity this fall and the hassles of dealing with corn that is too wet to harvest and profitably dry to safe levels before the snows begin to fall.  Also, take into account the final planting date for full insurance coverage for corn in your area. When replanting, the original stand of corn should be destroyed before you replant.  Late planted plants that grow next to an early-planted plant will be at a competitive disadvantage and will very likely not produce an ear. 

plsc.ransom.table 2

Joel Ransom

Extension Agronomist for Cereal Crops

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