This issue of Walking Your Fields newsletter contains articles about: yield monitor calibration, corn drydown and harvest timing and late season soybean diseases. Articles are written by DuPont Pioneer agronomists in Wisconsin and are distributed on behalf of DuPont Pioneer account managers and Pioneer sales reps.

1. Yield information from monitors and yield maps is an
extremely important tool that you can use to make deci-
sions in your business. However, it is only as accurate as
the calibration and taking time to do this will help elimi-
nate poor information later. Here are some tips to remem-
ber when looking at yield monitor calibration:
 Clear your memory card and back up previous year’s
data
 Calibrate multiple times throughout the growing sea-
son to ensure consistent data
 Make sure your load is enough weight (3,000-6,000
pounds)
 Make sure you have multiple loads at different speeds
(3.5, 4.5, 5 mph, etc.)
 Calibration loads should be in a uniform area of the
field, a good representation will improve accuracy
 Differences in moisture and grain quality will require a
new calibration to be accurate
In a year with variability, taking time to calibrate will pay big
dividends!
Many corn fields in the region were planted mid to late
May or early June, which means a lot of corn will likely
need until early October to reach maturity (black layer).
As growers hope for a late autumn to get field work done
before the snow flies, now is the time to weigh the cost of
in-field grain drydown versus using artificial drying at har-
vest.
There are three main factors that influence the rate at
which corn dries, physiological maturity, weather and the
corn hybrid. Corn that matures earlier typically dries fast-
er due to more favorable drying conditions earlier in the
harvest season. Similarly, later maturing corn has fewer
warm days to aid drying and will dry slower. In a typical
year, corn that matures on September 15 may require
only about 10-15 days to reach 20 percent moisture,
while corn that matures on September 25 may need 30
days to reach the same moisture level (D.R. Hicks, 2004).
Drydown is linked to heat units (GDUs). Under ideal
weather conditions, corn may lose up to one point of
moisture per day. As the days get cooler, GDUs decrease
and drying slows. A rule of thumb is that 30 GDUs are
required to lower the grain moisture each point from 30
percent to 25 percent. Forty-five GDUs per moisture point
are required from 25 percent to 20 percent. Also consider
that we typically expect no more than about 10 GDUs per
day in late September, and only about 3-5 GDUs per day
in late October. That means that field drying of corn may
take two to three times longer for late maturing fields.
Drydown is also hybrid specific. Long, tight husks as well
as hybrids of high test weight tend to dry slower than hy-
brids that don’t carry those characteristics.
The ideal harvest moisture for corn is between 22-25 per-
cent. Waiting for corn to dry to 18 percent moisture in the
field certainly saves on the energy bill; but it also increas-
es the likelihood of excess harvest losses due to stalk
lodging, ear drop and detrimental weather all of which
can affect your bottom line. In addition, there may not be
enough heat units this fall for in-field drydown. Ohio State
University research indicated no additional in-field grain
drying occurred after early to mid-November (Minyo,
Geyer & Thomison, 2009).
“Phantom yield loss” may also encourage growers to har-
vest at slightly higher moistures this fall. Growers occa-
sionally report harvesting part of a field early and finishing
the field when it is dryer, only to discover the later har-
vested portion of the field is yielding several bushels less
per acre than the first harvested corn.
Purdue University confirmed these claims indicating
that grain corn dried in the field has the potential to
WALKING YOUR FIELDS® newsletter is brought to you by your local account manager for DuPont Pioneer. It is sent to customers throughout the growing season,
courtesy of your Pioneer sales professional. The DuPont Oval Logo is a registered trademark of DuPont. PIONEER® brand products are provided subject to the
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Calibrating Yield Monitors
WALKING
YOUR FIELDS
®
www.pioneer.com
August 28, 2013 - Issue 5
Corn Drydown & Harvest Timing
Delaying harvest may increase risk of lodging, ear drop or kernel loss
and result in reduced yields. Photo: DuPont Pioneer
>>

2. yield one percent less per point of moisture. For example,
corn that was 200 bushels/acre at 28 percent moisture
would only yield around 180 bushels/acre at 18 percent
moisture if left in the field too long. This research also
confirmed that the ideal moisture level for corn grain har-
vest is 25 percent. Harvesting wetter than that can dam-
age kernels and of course significantly increase drying
costs (Nielsen et al., 1996).
Artificial drying costs will vary this season depending on
LP gas prices. Nonetheless, harvesting at a higher mois-
ture level this year may increase grower profitability, spe-
cifically when growers anticipate medium to high harvest
losses. The table below was developed by Iowa State
University, and customized by DuPont Pioneer agrono-
mists to illustrate different drying scenarios and costs
based on an average LP price of $1.35/gallon.
(Sources: Minyo, Geyer & Thomison. 2009. How will delaying corn har-
vest affect yield, grain quality and moisture? Ohio State University Ex-
tension. Nielsen et al. 1996. Kernel dry weight loss during post-maturity
drydown intervals in corn. Purdue University.)
What is the ideal harvest moisture for corn grain? Or,
to be more specific, what grain moisture will provide the
greatest economic return to the grower?
This is a question that has been studied and debated
over the years, with some growers favoring earlier har-
vesting, while others prefer drier grain to minimize artifi-
cial drying. While there is no definitive answer to this
question, limited research, and some reliable on-farm
anecdotes suggest grower’s yield may “disappear” after
physiological maturity due to respiring grain in the field.
(a.k.a. phantom yield loss) Additionally, field and harvest
loss due to ear drop and shelling may also impact har-
vestable yield.
To address this question, DuPont Pioneer is looking for
growers to run a simple test in their field this fall, compar-
ing a “early harvest” vs. “late harvest.” The test is easy to
do, and can be done with any corn hybrid:
1. Select a uniform field near bins or buildings that allow
for multiple harvests over time.
2. Harvest a portion of the field early, with grain mois-
tures near 25%.
3. Harvest a second time (or more) a week or more lat-
er, with final grain moisture targeted less than 20%.
4. Record harvest data with a yield monitor or weigh
wagon.
5. Note visible yield loss (dropped ears, etc.)
6. Provide harvest dates, yield & moisture data and
notes to your Sales Rep or DuPont Pioneer Agrono-
mist.
Contact your local Pioneer Sales Representative if you
are willing to participate in this test and to answer any
questions you may have. Again, we are looking for lots of
grower participation to help us address this question.
In a stressful growing season, attack from plant patho-
gens may begin to show up late in the year as patches of
dying or wilted plants with drooping or diseased leaves.
While soybean diseases may become apparent just prior
to harvest, the infection may have occurred much earlier
in the season. These above-ground symptoms are com-
mon to several
unique below-
ground problems.
A quick peek at
roots and lower
stems can help
determine which
of these patho-
gens might be at
work in your soy-
bean fields. Prop-
er identification
can help with fu-
ture variety selec-
tion and manage-
ment decisions.
Estimated Cost to Dry Corn to 15% Moisture
Harvest
Moisture
LP
gal/bu
LP
$/gal
LP
$/bu
Drying Cost
$/bu*
Drying cost
$/point*
35 0.472 1.35 0.637 0.645 0.032
30 0.337 1.35 0.455 0.461 0.031
25 0.219 1.35 0.296 0.299 0.030
20 0.109 1.35 0.147 0.149 0.030
Based on: NCH-51 Hybrid Maturity-Energy Relationships in Corn
Drying, Iowa State University; *assumes electrical cost of $0.115/kwh
Early Harvest Challenge Late-Season Soybean Diseases
Figure 1. Leaf necrosis caused by SDS or
BSR. Photo: DuPont Pioneer>>

3. Prevent Plant Acres Management
Sudden Death Syndrome (Fusarium virguliforme)
produces striking leaf symptoms (Figure 1), which alert us
to problems in the roots. Affected plants may die rapidly
after first leaf symptoms appear due to toxins produced
by the root rotting fungus. Split stems will generally show
only minor discoloration in solid cortex areas, with normal
white pith. Cool, moisture conditions early in the growing
season often results in higher disease incidence. Stress
due to heat and drought may reduce occurrence of SDS
in some cases.
Brown Stem Rot (Phialophora gregata) produces similar
striking leaf symptoms mid-season as SDS, which may
cause confusion
of the two diseas-
es. Tissues be-
tween veins be-
come yellow and
quickly turn
brown, except for
a narrow band of
green tissue out-
lining the vein.
However, BSR is
distinguished
from SDS and other diseases by brownish discoloration
due to an infection of the pith tissue in lower stems
(Figure 2). This infection impedes the movement of water
and mineral nutrients needed for growth.
White Mold (Sclerotinia Rot) Sclerotinia white mold is
favored by cooler night
temperatures (50-60°F)
and moist conditions in
the plant canopy. In ad-
dition to cool tempera-
tures, the production of
white mold apothecia
requires moist soil and a
closed canopy. The first
evidence of white mold
is a chlorotic, girdling
lesion covered with
white, fluffy mycelium at
one of the middle nodes.
The evidence of the dis-
ease becomes conspicu-
ous in August when
dead tops start to show
up in fields. It is most
likely to show up in low
spots of the field where plant populations are high, in nar-
row rows, in tightly closed canopies, where plants be-
come lodged and/or where less tolerant varieties are
planted.
Northern Stem Canker (Diaporthe phaseolorum) is a re-
emergent soybean disease that begins at points along
lower stems, creating brownish-red lesions (cankers) ex-
tending part way around and into lower stems (Figure 4).
Affected plants often retain dead leaves even up to har-
vest time. Roots and pith (the soft center are of stems)
are generally not affected by stem canker.
The challenging weather from this spring left a large
amount of acres unplanted in some areas of Wisconsin.
As a result, we are encountering fields that have a tre-
mendous amount of weed pressure. Annual weeds such
as giant ragweed, common lambsquarter, pigweed, and
waterhemp are all prolific seed producers. If left uncon-
trolled giant ragweed can produce 5000-10,000 seeds
per plant and common lambsquarter, waterhemp, and
pigweed are all capable of producing 100,000 seeds per
plant. The effects from not controlling these weeds can
potentially have long term effects from a weed control
standpoint. According to studies, it can take 12 years to
reduce a common lambsquarter weed seed bank by 50
percent, due to factors such as seed dormancy. It will
also be extremely important to evaluate your weed con-
trol program on these acres for next season. There could
be some early pressure from winter annual weeds like
shepherd's-purse and dandelions that will require a fall or
spring burn down. In addition, it will be very important to
have a good foundation herbicide program in place for
these acres next spring; not controlling this early weed
pressure could have a significant impact on yield.
Figure 4. Northern stem canker.
Photo: L. Osborne, DuPont Pioneer
Figure 2. Brown stem rot
Photo: L. Osborne, DuPont Pioneer
Figure 3. White Mold
Photo: DuPont Pioneer
Heavy shepherd’s-purse and common lambsquarter pressure in pre-
vent plant field. Photo: Brian Buck, DuPont Pioneer

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