Cor
(Continued from Page
pared the response to popula
tion of hybrids characterized by
seedsmen as flex, fixed ear or
prolific. The results of these
studies indicates there was little
relationship between a hybrids
classification and its yield
response to increasing the
population from 18,000 and
28,000. Also this study showed
that population responses are
quite variable and vary from
site to site and hybrid to hybrid.
Population studies are under
way here at Penn State and the
results will be shared as they
come available.
Row Cleaning
Devices
Row cleaning devices are
design to remove some of the
trash or crop residue from the
row to enhance emergence and
early season plant growth. A
number of options are avail
able. Among them are the
Dawn Trash wheel, Acra Trash
whippers, Rawson coulters,
and fluted coulters.
Research done with row
cleaning devices has been pub
lished from the Univ. of Ken
tucky and the Univ. of Guelph,
in Ontario. Kentucky research
ers found that residue removal
increased yields in one of three
years. They concluded that row
cleaning would be most benefi
cial on cool wet soils in springs
with plenty of sunshine.
Canadian researchers used
the row cleaners to plant into
rye cover crops. They found
consistent beneficial effects of
the row cleaners under these
conditions. They attributed this
benefit in part to reducing the
allelopalhic effects of the rye.
We began our research this
year with several row cleaning
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options. Preliminary results
indicate some potential to
improve plant populations by
up to 3,000 ppa with some of
the devices and increase soil
temperatures by 2-3 degrees F.
It’s 100 early too tell what the
potential of these will be, but
they may be able to help
improve no-till success on off
drained soils or in high residue
conditions.
Cultural Practices
And Corn
Rootworms
Corn rootworms have
become quite severe in some
pockets of the state recently.
Because of this, one has to ask
the question are we doing
something to receive this spe
cial treatment from this pest?
When we think of some of the
practices that we often recom
mend such as early planting,
no-tillage, and sidedress N fer
tilizer they all have one thing in
common the potential for
slow plant growth in the spring.
We were concerned that per
haps some growers may be set
ting themselves up for severe,
damage with these manage
ment practices. Two years ago,
we initiated a research project
to study how these cultural
practices influence the damage
from western com rootworm
larvae. Our results to date indi
cate little effect of any of these
practices on rootworm damage.
In fact, one comparison has
indicated that damage in 1992
was actually less where we
planted early. Here, the plants
had apparently had chance to
develop a vigorous root system
before the rootworm larva
emerged. This finding contra
dicts the concept that early
planted com is more at risk
because of reduced insecticide
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The effects of a soil insecti
cide on reducing damage in this
continuous com have been
much greater than any of the
other factors in the study. This
study is slated to be continued
for another year.
One technique that hasjseen
used to characterize the
response of hybrids to stress is
something called stability
analysis.
To measure the stability of a
hybrid, the hybrid yield from a
number of trials is plotted
against the average yield of
those trials. Some hybrids may
increase yields faster than aver
age, while others may perform
belter at lower yielding sites.
Stability analyses could be
used to place hybrids better. I
recently used this approach to
look at some hybrids that were
entered in our testing program.
I used some data from 1985,
when we had 15 locations of
data for our zone 1 trial. The
yields of the two top yielding
hybrids in the trial were plotted
against the test average yields..
This plot clearly showed that
one of the hybrids won all of the
comaprisons in the low yield
environments and the other
won all of the comparisons
from high yield environments.
Data from groups of industry
strip trials could be used for this
type of analysis to determine
hybrid stability. These would
be best if only hybrids common
to all trials were used to deter
mine the test average yields.
This research confirms that
growers should consider stress
tolerance characteristics of
hybrids in placing hybrids on
different fields around the farm.
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Corn Talk, Lancaster Farming, Saturday, February 13,1993—Page
€®]M SMI MlW§
Corn Maturity
Studies
This year we have begun a
new project to evaluate Grow
ing Degree Day requirements
of com in Pennsylvania. This is
a followup on some data that
two students have worked on
that shows that often com
hybrids in Pennsylvania require
fewer GDD’s to black layer
than seed companies report in
their literature. Our information
shows that in the State College
area, we grow hybrids that are
rated at 2600-2700 GDD’s and
the often require only 2300
GDD’s to harvest. These
hybrids are frequently planted
late into May and often have
little problem maturing (except
Test For My cotoxins
Richard Adams
PSU Extesnion
STATE COLLEGE (Centre
Co.) Mold problems with this
year’s corn crop arc widespread
due to the cool, wet growing sea
son and havesting problems.
Both whole-plant com silage
and com grain are involved. Pro
duction or weight gain problems
in livestock steam largely from the
degree of mold present.
Mycotoxins also may be
involved in some performance and
health problems when feed is
obviously moldy. However,
mycotoxins also may be present
when very little or no obvious
mold is seen.
Moderate reductions in milk
production or growth from feed
ing moldy grain or forages often
result from depressions in the
/ K /
PENNSYLVANIA MASTER CORN GROWERS ASSOC., INC.
Testing for mycotoxins should be consid
ered when otherwise unexplained and serious
reductions in performance occur, especially
when accompanied by related symptoms.
Quick tests using immuno-assay or TLC
methods may be employed for initial
screening.
Tests should include both aflatoxin and
Fusarium mycotoxins such as DON, DAS,
zearalenone, and possibly others. Such quick
tests often cost $lO-SSO each and are avail
able from some feed concerns, feed testing
laboratories, and veterinarians.
Preferably, frozen duplicates of samples
with a positive quick test should be sent for
more quantitative or confirmatory testing
using HPLC or gas chromatography.
While com is most suspect this year,
remember that all feeds used on a farm
including finished concentrates and especial
ly forages may contain mycotoxins. There
fore, other feeds also should be tested to sec if
they are the source of the mycotoxin or are
contributing one or more mycotoxins to the
problem.
Black or ultraviolet light scans are only
presumptive, since many false positives and
negatives may occur.
It is important to take representative sam
ples. It is best to take and freeze a composite
of each of three to five feedings. Then com
bine these and mix well before making a final
composite for submission.
Keep a frozen duplicate for conformalory
testing (requires a longer processing period)
in case a positive quick test is obtained, or
submit it at the same time as the initial lest.
Send about one pound of dried feed, core
samples from at least 12 bales of hay, or two
pounds of wet feeds such as silages, haylages
or wet brewers grains.
Place frozen samples in insulated bags con
taining frozen cold packs. Hand deliver the
in 1992). We are interested in
determining actual GDD
requirements of these hybrids
so that we can better predict
how far we can push maturity in
many areas of the state. We
have excellent long-term
weather information from
across the state that can be used
as a resource in this problem.
Summary
These studies represent only
part of the com research at Penn
Slate. Sizeable programs are
continuing in rotations, weed
control, soil fertility, physiolo
gy and breeding for disease
resistance. Because of space
constraints, only the highlights
of the studies discussed in this
report could be mentioned.
digestibility and palatability of
moldy feed.
More drastic reductions in per
formance of 15 percent to 25 per
cent or more within a few days to
a few weeks may signal a potential
problem with mycotoxins.
This is espccailly true when
health problems are present, such
as a marked drop in feed intake,
acetonemia or ketosis, increased
incidence of displaced abomasum,
hemorrhaging, diarrhea, and signs
of liver or kidney problems.
Black mold, which is a major
type seen in some of this year’s
crop, seldom produces mycoto
xins, but may appreciably reduce
performance.
Mold of other colors, when pre
sent in any amount, are more like
ly to produce mycotoxins.
(Turn to Page 26)
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