Corn Objective Yield Procedures (Training Materials)

Corn Objective
Yield Procedures

CODE 6 - DENT
Shucks are nearly dry, but not open. Most of the
ears and stalks are brown.

CODE 6 - DENT
Maturity line on kernels has not reached the cob.
Ears are firm and solid. Kernels may be hard to
scratch at the surface but still soft near the cob.
The ear is completely husked so it
does not interfere with the caliper
jaws. Measurement is taken one
inch from the butt of the ear. The
ear is in the mouth of the caliper
with the jaws at a 90 degree angle
to the ear. The caliper is read by
reading the top of the caliper to get
the tens place, and reading the dial
to get the units and tenths decimal.
This caliper measurement would be
recorded as 46.8mm (add arrows
and numbers to show where the 4, 6
and 8 are read if possible)

Hold the zero point of the tape at the
butt of the cob. Measure the length of
the kernel rows in inches and tenths
of inches. Do not include areas of the
cob with missing or damaged kernels.
If part of the ear is rotten or damaged,
visualize the kernels present forming
a continuous row from the butt toward
the tip.

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CODE 7 - MATURE
Shucks are dry and beginning to open. No green foliage
is present. Most ears have tipped completely over and
point towards the ground.

CODE 7 - MATURE
Kernels can be shelled off the cob fairly
easily. Moisture content may be as high as
32-33%. No milk can be squeezed from the
top of the kernel next to the cob. The “black
layer” is another indication of maturity. This
is an area near the tip of the kernel that appears dark.

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The width across 4 row spaces is measured from the center of the
plants in Row 1 to the center of the plants in Row 5.

CODE 2 - PRE-BLISTER
Ear shoots are present with some silks showing. Most silks
are green, yellow, or white in color. Only cob or hard spikelets can be felt through the husk.

CODE 2 - PRE-BLISTER
Spikelets contain little or no watery, clear liquid.

CODE 4 - MILK
Most kernels are full of milk-like substance. Kernels are
not fully grown and show little or no denting.

CODE 4 - MILK
Plant or shuck is green. Ears are erect
and silks protruding from the husks have
turned brown and dry.

CODE 3 - BLISTER

CODE 5 - DOUGH

Most silks protruding from the husks are beginning to
turn brown. Kernels can be felt through the husk.

Ear is beginning to lean away from the stalk and shucks
are starting to take on a light rust color. Visible silk is
completely brown and dry. About half the kernels are
dented and contain milk or dough-like substance.

CODE 3 - BLISTER
Most spikelets have swollen to
form kernels that contain watery,
clear liquid.

CODE 5 - DOUGH
Maturity line has not moved halfway to the cob on a
majority of the kernels.