Cool August temperatures have been the topic of discus-sion around the area. The cool temperatures have slowed GDU accumulations and have resulted in below average GDU accumulations to date. Fortunately, we still have time in August and early September to gain valua-ble GDU’s. Tracking GDU accumulation on your farm will help estimate management windows and crop growth stages. Pioneer.com allows you to calculate GDUs for your spe-cific location and planting date: https://www.pioneer.com/home/site/us/agronomy/tools/gdu/

Many corn fields in the region were planted mid to late May or early June, and that 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 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 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 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. The amount, thickness and tightness of husks affect drydown; the more insulated the ear, the longer it takes to dry. Upright ears are more prone to capture moisture in the husks. Lastly, corn with moderate test weight dries faster than hybrids with heavi-er test weights. 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

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.

Corn Drydown & Harvest Timing

WALKING YOUR FIELDS

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www.pioneer.com

August 28, 2013 - Issue 5

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

Growing Degree Unit Update

GDU Calculator

Location

2013 GDUs Accumulated

5/1 - 8/20

2012

5/1 - 8/20

30 Year Avg

+/- 30 Year Avg

Aberdeen, SD 1739 2048 1905 -166

Brookings, SD 1729 2085 1822 -93

Faulkton, SD 1839 2117 2011 -172

Huron, SD 1839 2225 2086 -176

Lisbon, ND 1802 2068 1844 -42

Oakes, ND 1755 1996 1842 -87

Watertown, SD 1676 2032 1842 -166

Wahpeton, ND 1645 1925 1838 -193

>>

harvested 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 the Midwest. 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 with permission by DuPont Pioneer agronomists to illustrate different dry-

ing 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 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.)

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. In a year with variability, taking time to calibrate will pay big dividends!

Tips for yield monitor calibration

Clear memory card and back up previous year’s data

Calibrate multiple times throughout the growing season to ensure consistent data

Make sure load is 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

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

Calibrating Yield Monitors

AGRONOMY RESOURCES, TOOLS & APPS

Pioneer.com and Pioneer mobile allow growers to have extensive crop management resources and agronomy information at their fingertips.

Pioneer® Field360™ Tools app

Keep fields at your fingertips and capture important information with this GPS powered field documentation tool.

Pinpoints your field location via satellite imagery and records notes or photos on the spot.

Instantly organize your crop scouting information by location to save or share.

Pioneer® Field360™ Notes app

Agronomy expertise from DuPont Pioneer in one app with field-level insights and real-time data.

Input a location, start date and CRM one time and easily navigate between the enhanced agronomy tools.

Track multiple field scenarios, view forecasts/daily precipitation, and calculate GDUs and key crop stages.

Email results - including screenshots of graphs and estimated growth 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 estimate an optimum planting rate for Pioneer® Brand Corn Prod-ucts.

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. Additionally, field and harvest loss due to ear drop and shelling may also impact harvestable 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 Rep-resentative if you are willing to partic-ipate in this test and to answer any questions you may have. Again, we are looking for lots of grower participa-tion to help us ad-dress this question.

Goss’s wilt is beginning to show up in corn fields around the central U.S. again this year. In 2012, the disease was found throughout much of the area despite the dry condi-tions in late summer and fall. This season, high winds along with sand/soil blasting that has occurred throughout June has likely created the kinds of injury necessary for Goss’s wilt bacteria to enter corn plants. The prolonged wet weather this spring is condu-cive to bacterial diseases in many crops, and corn has been no exception. Goss’s wilt is caused by a bacterial

pathogen and doesn’t respond to treatment with fungi-cides. It is best managed with resistant hybrids and sound cultural practices. Typical signs and symptoms of Goss’s wilt

Long, water-soaked, grayish-green patches or streaks that turn to large dead streaks with wavy margins

Dark ‘freckles’ within or just outside of leaf lesions

Lesions appear to spread along leaf veins (characteristic of bacterial disease)

Yellow-orange bacterial ooze (or dried ooze appearing as shiny flecks)

Stems may become plugged with bacteria, vascular bundles appearing orange to brown

The disease generally starts from inoculum surviving on previous (corn) crop residues, found at or near the soil surface. Early-season rainfall, especially when heavy or associated with high winds can lead to infection of the young corn crop. Early infection can produce the most devastating symptoms, including wilting and early plant death. Later infections typically affect leaves primarily, but may lead to early maturity, or reduced ear size and lower yields depending on the area affected and time of symp-tom onset. Risk factors to consider when planning for Goss’s wilt management

History of the disease in a field in last year or two indi-cates presence of inoculum

Continuous corn raises the risk of inoculum build-up

Reduced tillage tends to lead to slower residue break-down and greater risk that inoculum will remain in af-fected fields

Irrigated fields tend to have higher levels of disease incidence and severity

As in-season management of Goss’s wilt is difficult or impossible, be sure to select hybrids with the highest re-sistance level available for areas that have multiple risk factors mentioned above.

Early Harvest Challenge

Goss’s wilt symptoms on corn leaf. Photo: DuPont Pioneer

Goss’s Bacterial Wilt & Blight

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