(Continued from Page 18)
STANDABILITY
Standability is an especially important hybrid characteristic
in Pennsylvania, where the com harvest often continues
late into the fall. Poor standability is primarily due to stalk
rot, but can also be caused by weak stalks or root systems
Table 1. Approximate eeaeon length and growing
degree daya (GDDa) available tor Pennaylvanla com
maturity zonea.
maturity season
ZONE LENGTH (DAYS)
90-95
96-100 1825-2024
2 101-105 2025-2274 5/1-15
106-110 2275-2499
3 111-115 2500-2724 4/25-5/7
116-120 2725-2949
4 121-125 2950-3174 . 4/15-5/1;^
. /*«
.. *
126-130 3175 or >
as well as insect damage. Standability should be an
important consideration for fields where a shelled grain or
ear com harvest is planned, and especially for those that
will be harvested late. Considerable progress has been
made in improving standability, but important differences
still remain in commercial hybrids.
A CLEAN SIUT IN NO-1U
suns MIN MONMIR
ECONOMICAL PRICE
• Roundup herbicide fits right in with the lower input costs of no-till
farming.
BROAD-SPECTRUM PE
• Roundup controls over 100 different broadleaves and grasses.
RELIABLE RESULTS
•Thanks to its unique roots-and-shoots activity, Roundup works the first
time-every time.
APPLICATION FIEXIBIUIY
• Roundup lets you eliminate emerged weeds anytime before planting,
at planting or after planting (but before crop emergence).
• Roundup can be tank-mixed with most residual herbicides and liquid
nitrogen fertilizers.
• See us to discover how a clean start with Roundup
herbicide can give you a head start to higher yields.
CONTACT YOUR LOCAL DEALER FOR MORE INFORMATION
ABOUT THE ADVANTAGES OF ROUND UP HERBICIDES
Always wd and loUo* Kit laM (or Roundup hartmda Hounds* a tagialamd trademark ol Monsanto Company {Monsanto Company 1993
Considerations for
selecting com hybrids
APPROXIMATE
AVAILABLE
ODDS
PLANTING
DATES
1600-1824 5/15-25
YIELD PERFORMANCE
Hybrid yield performance is a critical factor in hybrid
selection. The range in yield potential among commercial
hybrids frequently is greater than 40 bushels per acre
(Table 2). It is essential that performance information be
based on the results of several trials and not just one test.
Average performance from a number of sites in your region
is often a better indicator of future performance than the
results of a single test on your farm. Also consider moisture
differences between hybrids when evaluating for yield. At a
drying cost of $0.04/point/bushel and a com price of $2.50
per bushel, every 1% moisture difference between two
hybrids yielding 125 bushels per acres is worth 2 bushels
per acre. This is especially important for com that will be '
shelled and dried.
When interpreting yield performance tests grown over
a wide region, consider only those hybrids with a maturity
adapted to your farm, even though later hybrids in these
tests may have higher yields. When grown under your
conditions, these later hybrids may not yield as well, and
they will have higher moisture levels and an increased risk
of frost before maturity. Yield performance can be best
estimated by actual harvest-time measurements of grain
production. Visual estimates of yield based on ear size;
kernel rows, or kernel depth are not reliable enough to use
for hybrid comparisons.
When evaluating hybrids for silage production, it is
best to base decisions on silage yield performance data if
possible. Where this information is not available, a tall,
leafy, hybrid with a good grain yield potential would likely
be a good choice for silage.
iRMANCE
Roundup
<4* X
GET A CLEAN START M NOTH
Corn Talk, Lancaster Farming, Saturday, April 17,1993-Page
(O®lW fM M MEWS
m
Tabla 2. Two-yaar avaraga and ranga In ylalda and
molatura for hybrlda antarad In both 1990 and 1991
Pennaylvanla Commarelal Hybrid Com Taata.
YIELD YIELD MOISTURE MOISTURE
MATURITY AVERAGE RANGE AVERAGE RANGE
ZONE (BU/A) (BU/A) (%) (%)
A number of other special hybrid characteristics should be
considered in selection for specific situations. The impor
tance of these characteristics depends on the specific
situation. Generally, they should have a major impact in
hybrid selection only if they wiJLJiave an impact on the
yield and quality of the final product. These characteristics
include harvestability as ear com, seedling vigor, test
weight, tight husk cover for bird resistance, stay-green
potential, and grain or silage quality.
Harvestability of a hybrid can be particularly important
for ear com producers. Some hybrids have the tendency to
lose kernels from the ear during the picking process,
lowering the yield and quality of the ear com. On other
hybrids, husk removal is sometimes difficult, which
contributes to reduced airflow in the bin and increases the
potential for spoilage.
Differences in seedling vigor do exist between hybrids
and can have an effect on stand establishment in stressful
situations, such as early planted no-till com or com planted
into heavier, wetter soils. The importance of seedling vigor
under most other situations, however, is probably second
ary compared to maturity, disease resistance, and yield
performance.
Test weight differences also exist between hybrids and
these should be considered if higher test weight is an
advantage from a marketing standpoint. Studies have
shown that test weight is not a good indicator of feed value,
so there is likely to be little advantage from feeding high
test-weight hybrids.
For growers who frequently experience serious losses
from bird damage when com is in the milk stage, husk
tightness and coverage may be important considerations.
Many of the new hybrids being developed possess
increased levels of what is known as stay-green, or the
ability to retain leaf color past physiological maturity. This
characteristic appears to improve late season plant health
and to increase the grain dry-down rate. This characteristic
may also help to extend the harvest window for silage
production by reducing the whole-plant dry-down rate.
Grain and silage quality differences should also be
considered, since feed quahty differences do exist among
hybrids. However, you should monitor the economics of
134 93 128
1 120 88-136 21.3 18.9-23.2
2 118 90-136 25.2 20.3-27.2
3 126 81-139 23.0 19.4-25.1
4 147 122-170 23.5 20.4-24.7
SPECIAL CHARACTERISTICS
growing hybrids with improved quality traits Frequently,
quality differences among hybrids are small and the yield
differences among comparative hybrids arc much greater
You usually can’t afford to give up very much in yield
performance to get the improved quality. In hybrid testing
trials, quality differences among groups of hybrids have
been shown to range up to 1 percentage point in grain
protein and 2 to 3 percentage points in silage digestibility.
Recent advances in biotechnology may allow a wider range
of hybrid quality differences in the future.
MANAGEMENT INTERACTIONS
The idea that hybrids differ in their adaptation to different
management practices such as tillage systems, nitrogen
rates, populations, and soil productivity levels remains an
area of great debate. One group in this debate contends that
hybrid differences under these practices are small and
difficult to predict. On the average, this group suggests
using hybrids that have performed well under a wide range
of conditions. The other group contends that hybrids
respond consistently different to some of these changes and
that these responses should be incorporated into your plan
of placing hybrids in different fields on your farm. Recent
research results are beginning to clarifysome of these
differences.
Recent studies have shown that the best hybrids in
conventional tillage are also usually the best in reduced
tillage systems. One notable exception to this would be the
need for higher gray leaf spot resistance where this disease
is a problem Another consideration may be to put added
emphasis on seedling vigor in early season no-till plantings
On the whole, however, tillage practice should not have a
large impact on your hybrid selection
In controlled situations in the greenhouse or labora
tory, some researchers have shown differences in how
hybrids respond to different forms and timings of N
applications. When others have tried to document this in
the field, however, they have generally been unable to
consistently show the same type of differences In general,
research has shown that different hybrid responses due to
the growing seasons are much greater than any differences
215