Stage Brief description Days after silking Days to maturity Kernal
 moisture
%

 
R2 Blister
  • White blister shaped kernals develop
  • Inner fluid clear
  • Severe stres can cause kernals to abort
10-14 45-51 85
R3 Milk
  • Kernals yellow on outside
  • Inner fluid is milky white, high in sugar
  • Kernals can still abort, but not as easy
18-22 37-43 80
R4 Dough
  • Starch accumulation increases, inner fluid is pasty
  • Soft dough-55% kernals dented
  • Hard dought-90% kernals dented
  • At about 1/2 mature kernal dry weight
24-28 31-37 70
R5 Dent
  • Nearly all kernals dented in the crown
  • Milk line starts to move down--line seperating liquid milky & solid starchy areas
  • Stress can reduce kernal weight and yield
Marurity Indicator--Milk line half way down the kernal
90%-95% final dry weight in kernal

Milk line three quarters down
Whole plant moisture about 65% to 70%
    "silage harvest stage"
35-42



45-53





50-59
20-23




10-12







5-6
55


45







40
R6 Physiological Maturity
  • Milk line reaches bottom of the kernal
  • Kernals reach maximum dry weight
  • Black layer forms
  • Safe from frost, field drydown begins
55-65   30-35


Estimating Corn Yields Prior to Harvest

Estimate ears per 1/1000 acre (planting population)
Chose an average ear, count kernal rows and number of kernals per row

(avg ear) x (avg row #) x (avg kernal #)
                        90

Example:  Planted at 34,000, so estimating 31 ears per 1/1000 acre
                Picked an average ear that had 16 rows and had 35 kernals per row

Equation:  31 x 16 x 35 =  192.8 bu/acre estimation
                      90
 
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