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.

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 terms and conditions of purchase which are part of the labeling and purchase documents. ®, TM, SM Trademarks and service marks of Pioneer. © 2013 PHII.

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

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

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.

1All 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

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