May 11, 2018   
  Issue 2  

Prepared by

Paul Kassel

Extension Field Agronomist



(712) 262-2264




Serving Clay, Buena Vista, Dickinson, Emmet, Hancock, Kossuth, Palo Alto, Pocahontas, Sac and Winnebago Counties



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The Iowa State University Extension and Outreach Policies Page.  


























Corn Planting date. The ISU planting date studies in northern Iowa have yield and grain moisture data for three planting dates - late April, mid-May and early June. There is not a late May planting date in this data set.
The following data is from one year of a date of planting study from the ISU Northern Farm at Kanawha - and should be considered a very general overview of the effects of delayed planting.
The three corn hybrids are 95 day, 104 day and 109 day.
Plant date             P9526           P0407               P0987                        average
                        yield    H20     yield    H2O    yield    H2O                yield    H2O
                        bu/a     %         bu/a     %         bu/a     %                     bu/a     %
5/13/15            179      14.5     169      15.0     196      16.7                 181      15.4
6/5/15              169      19.1     139      20.8     161      20.2                 156      20.2    
The effect of an early June corn planting date compared to mid- May corn planting date:
-   Corn yields decreased about 1.0 bu/acre/day or 25 bu/a.
-   Corn grain moisture increased 4.8 points, or 0.2 point/day.
-   The cost of drying 200 bushel per acre corn is about $7.00 per acre per point.
-   a later maturity hybrid needs to yield an additional 2 bu/a to offset extra drying costs - based on $3.50 bushel corn.  
A study with the same hybrids at the ISU Northwest Research Farm near Sutherland showed:
-   more of a yield advantage for the 109 day hybrid at all planting dates.
-   that the yield penalty for delaying the planting date from mid -May to early June was about 50 bu/a in 2014, 20 bu/a in 2015 and 10 bu/a in 2016.
Black cutworm . Numerous black cutworm adults have been caught in southern Minnesota . Moth trap info will not predict the severity of potential black cutworm damage. However, this trap data is important to predict when corn may be damaged by black cutworm. Early planted corn will likely large enough to be damaged by black cutworm larvae by late May.
Later planted corn and corn yet to be planted can be especially susceptible to cutworm damage and will need to be checked for damage after corn emergence.
ISU Custom Rate. The most recent Custom Rate Survey is available on ISU's Ag Decision Maker website. 

Prepared by Paul Kassel, Extension Field Agronomist

Phone: (712) 262-2264, Email: