Page 18—Corn Talk, Lancaster Farming, Saturday, October 11, 1997
Diagnosing Downed Corn Can Be Frustrating
Dr. Greg Roth
Penn State Agronomy
Associate Professor
Harvesting com that has fal
len down can be a real frustra
tion, especially when you’re
trying to make time during the
busy harvest season.
Like one farmer recently told
me, when there are two tractor
trailers wailing to be filled at
the edge of the field and the
weather is uncertain, you don’t
want to have to be running the
combine at one mile an hour
because the com is down. So
it’s not surprising that standa
bility is an important considera
tion for many fanners in assess
ing their hybrids and other
management practices.
Early fall is an excellent time to assess
lodging problems in com, for two reasons.
One, you can make harvest plans that take
into consideration fields that might have
down com problems and, two, you can
leam what caused the problem to avoid it
in the future.
If you identify fields that have a poten
tial lodging problem early in the fall, they
should be harvested as early as possible to
avoid more serious problems and
increased harvest losses. Down com is
more subject to animal damage and ear
molds.
Com lodges for four basic reasons: root
lodging, stalk rots, European com borer
damage, or com rootworm damage. Each
of these could be a factor in fields this fall,
but the management to avoid these prob
lems in the future is different so it pays to
identify the problems before harvest.
Root lodging occurs when a poor root
system develops, the soil gets wet in the
fall, and windy conditions uproot the crop.
The poor root development can be asso
ciated with some hybrids and is also asso
ciated with dry conditions in July, as many
areas experienced this year.
Generally the root system is not injured
but is small. This problem can also be pre
sent in wet years when com root systems
are relatively shallow. Most seed compa
nies provide a root rating for their hybrids.
If the root lodging is more than an isolated
case, consider switching to a hybrid with
stronger roots.
Com rootworm damage appears similar
to root lodging in that the plants are some
times uprooted, but often this is accompan
ied by the goosenecked plants that lodged
earlier in the season. Roots will also shown
signs of com rootworm injury, chewed-off
roots, or root tips. Often, you may have to
wash the root system to find these symp
toms late in the season. Com rootworm
damage has been common this year but
usually only in com following com. If this
problem is common, consider more crop
rotations or reevaluate your soil insecticide
program.
Stalk rot also can be a common cause of
down com, especially following a stressful
late season with cloudy weather, leaf dis
eases, or nutrient deficiencies. Stalk rot
usually causes the stalk to bend and break
below the ear and is caused by one or more
fungi weakening the tissues in the lower
portion of the stalk. Often the pith in the
lower stalk will be nearly gone and discol
ored either pink or gray. Sometimes the
stalk will appear black as well. Stalk rot is
often associated with gray leaf spot, so
selecting hybrids with good tolerance to
gray leaf spot may be necessary.
Stalk rot can also be related to low soil
potassium levels or excessive plant popu
lations. Stalk rot can also be managed
through hybrid selection, since hybrids
also vary in their resistance to various stalk
European com borer damage
is another cause of downed
com. Often plants will break
over at or below the ear. There
will usually be signs of com
borer waste or frass near the
break and splitting a few stalks
will usually reveal signs of the
com borer tunneling. All fields
will have some com borers, but
when you find more than 1-2
borers per plant, this is often
associated with a significant
lodging or a yield loss problem.
Damage is often most severe on
late-planted fields. Manage
ment of this pest is best accom
plished using Bt hybrids on
high-risk fields.
If you encounter some down
com this fall, take some time to
&
hEW HOLLAND
1 1/2 Miles East
of Abbottstown,
Pa West of
York, PA
On Route 30
717-259-6617
evaluate the problem or, at a
minimum, take a few plant
samples to share with your crop
WASHINGTON, D.C.
The Com Refiners Association
is very disappointed with the
recent decision by Mexico’s
Trade Ministry to impose tar
iffs on com syrup imported
from the United States.
In doing so, the Mexican
government turned its back on
the North American Free Trade
Agreement, which was estab
lished to ensure easy import
and export access between the
United States, Mexico and
Canada.
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adviser. Careful identification
can help to get the problem cor-
Corn Refiners Disappointed
CRA President Charles F.
Conner stated, “Unfortunately,
Mexico’s Commerce Depart
ment (SECOFI) has based its
investigation into imports of
U.S. high fructose com syrup
(HFCS) on false allegations
from the Mexican Sugar
Chamber.”
In a meeting with SECOFI
representatives on June 6, the
Com Refiners Association ex
pressed hope that any decision
on HFCS would be made ac
cording to NAFTA and WTO
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been the case
The Com Refiners Associa
tion will continue to cooperate
with Mexico in resolving this
investigation. Conner said,
“The CRA is confident that
SECOFI continues to support
the spirit of NAFTA and free
trade between Mexico and the
United States and we urge
them to brush aside the politi
cal pressures from those ele
ments in Mexico that fear fair
competition from U.S com.”
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