As we approach the conclusion of the 2013 cropping sea-son in our area, we’re nibbling our nails a bit. Concern over crop maturity has many wondering if we’re in a race to the finish line with mother nature (or even Jack Frost!) We’re certainly going to be pushing up against a time when killing frosts are a possibility, and with that comes some risk of delayed maturity and potentially reduced yields and light weight grain. In looking at how crops are developing, the corn seems to be playing catch-up in many areas with milk-ripe (R3) stage corn giving way to dough stage and even some denting kernels. As of Au-gust 19, MN reported about 27 percent of corn as dough stage compared to a five-year average of 47 percent, slightly behind, while SD corn was slightly ahead of the average at 65 percent dough-stage. Both states were near average levels for soybean pod set. Corn needs about 200-300 GDUs (10-20 days) from 1/2-milk line stage (dent) to reach black layer. Soybeans require about 15-18 days from R6 (filled pod at top four nodes) to physi-ological maturity. Both crops usually require some time to dry for ease of harvest, but a killing frost after maturity should not affect yields or grain quality. Have a safe and productive harvest season!

Yield data from combine monitors can be an im-portant tool that you can use to make decisions in your business. However, it is only as accurate as the calibration, and taking time to do this will help elimi-nate poor infor-mation later. Here are some tips to remember when look-ing at yield monitor calibration:

Back up prior year’s data and clear memory cards

Calibrate during the growing season as needed to en-sure consistent data across your farm.

Make sure your calibration loads hare heavy enough to provide an accurate test (3,000-6,000 pounds)

Make sure you take calibration loads at different speeds (3.5, 4.5, 5 etc.) to simulate higher and lower yields

Calibration loads should be in a uniform area of the field, a good representation will improve accuracy

Major differences in moisture and grain quality (test weight) will require a new calibration to be accurate.

Many corn fields in the region were planted mid to late May or early June, this corn will likely need until early Oc-tober 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 harvest. 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. On the same note, 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

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.

Coming Into The Home Stretch!

WALKING YOUR FIELDS

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www.pioneer.com

August 28, 2013 - Issue 5

Growing Degree Unit Update for the Area

Location

GDU since May 5

Departure from

Normal

Predicted GDUs to 9/2 (departure)

Alexandria, MN 1688 -62 1976 (0)

Morris, MN 1762 -8 2035 (+48)

Montevideo, MN 1793 -143 2083 (-95)

Marshall, MN 1826 -75 2119 (-19)

Brookings, SD 1703 -81 2007 (+2)

Luverne, MN 1842 -74 2137 (-18)

Sioux Falls, SD 1840 -178 2146 (-133)

Source: www.pioneer.com GDU Calculator

(May 5 - August 19, 2013, forecast through Sept. 2)

Calibrating Yield Monitors

Grower enters calibration data into his yield monitor during corn harvest. Photo: Case IH.

Corn Drydown & Harvest Timing

>>

require only about 10-15 days to reach 20 percent mois-ture, 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 de-crease 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 GDU’s per day in late September, and only about 3-5 GDU’s per day in late October. That means that field dry-ing of corn may take two to three times longer for late maturing fields. Dry-down is also hybrid specific. The amount, thickness and tightness of husks affect drydown; the more insulated the ear, the longer it takes to dry. Up-right ears are more prone to capture moisture in the husks. Lastly, corn with moderate test weight dries faster than hybrids with heavier test weight.

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 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 harvest is 25 per-cent. Harvesting wetter than that can damage kernels and of course significantly increase drying costs (Nielsen et al., 1996). Artificial drying costs will vary this season depending on LP gas prices, which currently range from $1.25 - $1.40 per gallon across Minnesota. Nonetheless, harvesting at a higher moisture level this year may increase grower profitability, specifically when growers anticipate medium to high harvest losses. The table below was developed by Iowa State University, and customized by DuPont Pio-neer agronomists to illustrate different drying scenarios and costs based on an average LP price of $1.35/gallon. If you have questions about moisture levels, drydown and harvest, contact your local sales representative for assis-tance.

(Sources: Minyo, Geyer & Thomison. 2009. How will delaying corn harvest affect yield, grain quality and moisture? Ohio State Univer-sity Extension. Nielsen et al. 1996. Kernel dry weight loss during post-maturity drydown intervals in corn. Purdue University.)

Delaying harvest may increase risk of lodging, ear drop or kernel loss and result in reduced yields. Photo: DuPont Pioneer

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

Propane tanks and grain dryer set-up on bins. Photo: Mark Jeschke

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. Affect-ed plants may die rapidly after first leaf symptoms appear due to toxins pro-duced 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 diseases. Tissues between

veins become yellow and quickly turn brown, except for a narrow band of green tissue outlining the vein. How-ever, BSR is distin-guished 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 addition to cool temper-atures, the production of white mold apothecia requires moist soil and a closed canopy. If surface soil moisture is low or the soybean canopy is not closed during flowering, the fungus would not be able to produce apothecia. When scouting for this disease, pay attention to the fields that

have a history of white mold and fields that have good soil moisture 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 evi-dence of the disease becomes conspicuous 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 popula-tions are high, in narrow rows, in tightly closed canopies, where plants become lodged and/or where less tolerant varieties are planted. Northern Stem Canker (Diaporthe phaseolorum) is a re-emergent soy-bean disease that begins at points along lower stems, creating brown-ish-red lesions (cankers) ex-tending part way around and into lower stems (Figure 4). Affected plants often retain dead leaves even up to harvest time. Roots and pith (the soft center are of stems) are generally not affected by stem canker.

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

Figure 4. Northern stem canker. Photo: L. Osborne, DuPont Pioneer

Figure 3. White Mold Photo: DuPont Pioneer

AGRONOMY RESOURCES, TOOLS & APPS

Pioneer® Field360™ Tools app

Keep fields at your fingertips Pinpoints your field location and records notes or photos on the spot.

Pioneer® Field360™ Notes app

Agronomy expertise in one app in real time Track scenarios, view precipitation map, calculate GDUs and key crop stages.

Pioneer® Field360™ Plantability app

This planter settings calculator gives precise planter settings for corn and sunflower seeds of all sizes and shapes.

Pioneer Planting Rate Estimator

Examine historical yield response curves to help find and optimum planting rate for Pioneer® Brand Corn Products.

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