Learn more about late season soybean diseases, how to manage prevented plant acres, fall tillage options and yield monitor calibration tips in this August issue of Walking Your Fields newsletter. Articles are written by DuPont Pioneer agronomists in southeastern Minnesota and are distributed on behalf of DuPont Pioneer account managers and Pioneer sales reps.

1. 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 pathogens might be at work in your soybean fields.
Proper identification can help with future variety selection
and management decisions.
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,
moist 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 diseases. Tissues between
veins become yellow and quickly turn brown, except for a
narrow band of green tissue outlining 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 infec-
tion impedes the
movement of water
and mineral nutrients
needed for growth.
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WALKING
YOUR FIELDS
®
www.pioneer.com
August 28, 2013 - Issue 5
The challenging weather from this spring left a large
amount of acres unplanted across Southern Minnesota.
As a result, we are encountering fields that have a tre-
mendous amount of weed pressure; the heaviest pres-
sure weeds include common lambsquarter, giant rag-
weed, pigweed, waterhemp, shepherd's-purse, and dan-
delions. Weed pressure is extremely heavy in fields that
have not been tilled; however, a second flush of weeds is
also becoming present in fields with small grain cover
crops as well. Annual weeds such as giant ragweed,
common lambsquarter, pigweed, and waterhemp are all
prolific seed producers. If left uncontrolled giant ragweed
can produce 5000-10,000 seeds per plant and common
lambsquarter, wa-
terhemp, and pig-
weed are all capa-
ble of producing
100,000 seeds per
plant. The effects
from not controlling
these weeds can
potentially have
long term effects
from a weed con-
trol standpoint. Ac-
cording to studies,
it can take 12 years
to reduce a com-
mon lambsquarter
weed seed bank by
50 percent, due to
factors such as seed dormancy. Moving forward, weed
control this summer in prevent plant and cover crop acres
is very important (especially the hard to control weeds
such as waterhemp); it will pay dividends when it comes
to weed pressure in next season’s crop. It will also be
extremely important to evaluate your weed control pro-
gram on these acres for next season. There could be
some early pressure from winter annual weeds like shep-
herd's-purse and dandelions that will require a fall or
spring burn down. In addition, there could be a large in-
crease to the annual weed seed bank that could result in
extremely heavy weed pressure early next spring. It will
be very important to have a good foundation herbicide
program in place for these acres next spring; not control-
ling this early weed pressure could have a significant im-
pact on yield.
Prevent Plant Acres Management
Figure 3. Heavy shepherd’s-purse and
common lambsquarter pressure in pre-
vent plant field. Photo: B. Buck, DuPont
Pioneer
Late-Season Soybean Diseases
Figure 1. Leaf necrosis caused by
SDS or BSR. Photo: DuPont Pioneer
Figure 2. Brown stem rot. Photo: L.
Osborne, DuPont Pioneer

2. Where is Our Corn At?
Data from Faribault, MN
This year has been one for the record books. We have
experienced tremendous ups and downs. Below is an
illustration of the ups and downs we have experienced
from mid-May thru August 16.
Planting: We started with a very wet planting season.
This put most corn in SE Minnesota in the ground either
mid-May or early June, outside of some pre-snow corn
and mid-June corn. Notice on the graph below, the first
two circles in that time frame. After each planting window,
we were faced with cold wet snaps which delayed emer-
gence of the corn crop. This is significant because it de-
layed emergence and put the crop behind its expected
stage based off of GDUs. Despite the challenges, plant
populations have been very good in most fields which
leaves the crop the opportunity for good yields.
Mid-Season: After the very difficult start, the rain stopped
and the heat was turned up as seen below. This heat
spell brought us to average GDU collection and also
brought many early fields to the pollination stage. Starting
July 23 however, the heat turned off. This was great for
tasseled corn to ensure great pollination, but this period
put the crop at great risk of not hitting black layer in many
fields. To put this cold snap in perspective, from July 23
through the last date collected below (August 16), it has
been 25 straight days of below average GDU collection
during what is normally the dog days of summer. This has
left us 116 GDUs off of average for the example of a May
15 planting date. Another key piece is that corn was
planted late, missing out on some early season heat. The
last third of August has begun to heat up again, and if we
carry that into September and avoid an early killing frost,
there is potential for some good yields in many fields.
Frost: Frost averages by location vary as much as a
week or two through much of southern MN. Also keep in
mind it takes a temp of 28°F for four hours to be a killing
frost in corn. This means for Faribault, MN in the example
below, there is a 25 percent chance of a killing frost by
Oct. 1. The link provided gives locations throughout Min-
nesota, so you can reference a point closer to home.
There are two exciting new tools developed by DuPont
Pioneer®
for tracking everything discussed in this piece,
they are Pioneer®
Field360™ Tools app and Pioneer®
Field360™ Select software. Contact your local sales rep
for more information.
www.climate.umn.edu/normals/index_freeze_date.htm
**** The above charts and data were generated using the Pioneer®
Field360™ Tools App

3. a 20% separate corn borer refuge must be planted with Optimum AcreMax Xtra
products. YGCB - The YieldGard®
Corn Borer gene offers a high level of re-
sistance to European corn borer, southwestern corn borer and southern cornstalk
borer; moderate resistance to corn earworm and common stalk borer; and above
average resistance to fall armyworm. LL - Contains the LibertyLink®
gene for
resistance to Liberty®
herbicide. RR2 - Contains the Roundup Ready®
Corn 2 trait
that provides crop safety for over-the-top applications of labeled glyphosate
herbicides when applied according to label directions.
Herculex®
Insect Protection technology by Dow AgroSciences and Pioneer Hi-
Bred. Herculex®
and the HX logo are registered trademarks of Dow AgroSciences
LLC.
YieldGard®
, the YieldGard Corn Borer Design and Roundup Ready®
are regis-
tered trademarks used under license from Monsanto Company.
Liberty®
, LibertyLink®
and the Water Droplet Design are trademarks of Bayer.
Yield information from monitors and GPS 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 re-
member when looking at yield monitor calibration:
 Clear memory card and back up previous year’s data
 Calibrate multiple times throughout the growing sea-
son to ensure consistent data
 Make sure loads are enough weight (3,000-6,000
pounds)
 Make sure you have multiple loads at different
speeds (3.5, 4.5, 5 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!
Opportunities for Tillage
 Primary tillage is most effective at lifting soil com-
pacted layers and producing an even shattering ef-
fect across the width of the tillage tool.
 Appropriate levels of residue incorporation can be
accomplished which increases soil to residue contact
enhancing residue breakdown without layering resi-
due and causing seedling residue interactions (corn
on corn concern)
 Residue sizing and corn root ball management can
be more effective with the use of corn head chop-
pers or stalk choppers combined with vertical tillage
tools prior to primary tillage.
 Deep tillage will not ‘dry out your soils’.
 Make every attempt to incorporate and reduce large
residue for next spring planting.
Calibrating Yield Monitors
The table above shows top selling Pioneer®
brand hy-
brids for SE Minnesota. The key takeaway is the Physi-
cal-CRM. A great example of this is Pioneer®
hybrid
P0533AM1™ brand. This product is marketed as a 105
day because of its late season harvest moisture even
though it black layers at a maturity of 101 day. This is a
huge bonus this year when reaching to black layer is the
critical factor. Also, it is important to note the Silk CRM.
The earlier the silking date, the less impact an early frost
would have on the hybrid. Finally, GDUs of when a hy-
brid will mature still varies by environment. Example:
Acres that had extended emergence periods due to satu-
rated conditions like this spring will be behind the “on
paper” black layer date.
1
All Pioneer products are hybrids unless designated with AM1, AM, AMRW, AMX
and AMXT, in which case they are brands.
AM1 - Optimum®
AcreMax®
1 Insect Protection System with an integrated corn
rootworm refuge solution includes HXX, LL, RR2. Optimum AcreMax 1 products
contain the LibertyLink®
gene and can be sprayed with Liberty®
herbicide. The
required corn borer refuge can be planted up to half a mile away. AMRW - Opti-
mum®
AcreMax®
RW Rootworm Protection system with a single-bag integrated
corn rootworm refuge solution includes HXRW, LL, RR2. AM - Optimum®
Acre-
Max®
Insect Protection system with YGCB, HX1, LL, RR2. Contains a single-bag
integrated refuge solution for above-ground insects. In EPA-designated cotton
growing counties, a 20% separate corn borer refuge must be planted with Opti-
mum AcreMax products. AMX - Optimum®
AcreMax®
Xtra Insect Protection sys-
tem with YGCB, HXX, LL, RR2. Contains a single-bag integrated refuge solution
for above- and below-ground insects. In EPA-designated cotton growing counties,
Pioneer®
Brand Leaders by Maturity
Fall Tillage
Table 1. Expected percent of maximum grain yield and associ-
ated grain moisture content of corn at five growth stages. If a
killing frost occurs between early dent and full dent expect 80-
90% of the yield you would experience at physical maturity.
Stage
% of Max
Grain Yield
Grain Moisture Content
(%)
Silk 0 -
Blister 0-10 85-95
Early Dent 60-75 50-55
Full Dent 90-95 35-40
Phys. Mat. 100 25-35
P9675AMX™ AMX,LL,RR1 96 93 96 1160 2300
P9807HR HX1,LL,RR2 98 103 100 1280 2400
P9834AMX™ AMX,LL,RR2 98 99 99 1240 2370
P9910AMX™ AMX,LL,RR2 99 102 102 1270 2450
P9917AMX™ AMX,LL,RR2 99 96 98 1200 2350
P0062AMX™ AMX,LL,RR2 100 99 101 1240 2420
P0193AM™ AM,LL,RR2 101 101 101 1260 2420
P0392AMX™ AMX,LL,RR2 103 103 101 1280 2420
P0448AMRW™ AMRW,LL,RR2 104 102 104 1270 2500
P0533AM1™ AM1,LL,RR2 105 97 101 1210 2420
HYBRID/
BRAND1
CRM
SilkCRM
Phy.CRM
GDUsto
Silk
GDUsto
Phy.
Maturity

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