Skip Navigation

10/12/2009 - 10/18/2009

Integrated Crop Management Conference set for Dec. 2 and 3

By Brent Pringnitz, ISU Agribusiness Education Program

The Iowa State University Integrated Crop Management Conference will be held Dec. 2 – 3 on the Iowa State University (ISU) campus. Registration begins at 7:30 a.m. on Dec. 2 in the Scheman Building and the program concludes at 4:00 p.m. on Dec 3.

Conference attendees can choose from 34 different workshops that offer the latest information on crop production and protection technology in Iowa and surrounding states. Workshops are offered by ISU faculty and staff and invited speakers from around the Midwest. The conference is hosted by ISU Extension, the College of Agriculture and Life Sciences and the departments of Agronomy, Entomology, Plant Pathology and Agricultural and Biosystems Engineering.

A popular feature of the conference is the variety of guest speakers on the program. Each year ISU specialists invite colleagues in their field to share their research activities with conference attendees. This provides an opportunity to hear expertise and opinions from across the region and country in one location. Invited speakers this year include:

• Emerson Nafziger, extension agronomist, University of Illinois, speaking on the agronomics of high-yield corn
• Chris Boerboom, extension weed scientist, University of Wisconsin, on herbicide injury in soybeans
• Seth Naeve, extension soybean specialist, University of Minnesota, on the little things in management that impact overall soybean yield
• Tamra Jackson, plant pathologist, University of Nebraska, discussing the reemergence of Goss’s Wilt in Midwestern corn

In recent years the conference has filled to capacity with nearly 1,000 producers and agribusiness people in attendance.

Attendees can obtain up to 14 Certified Crop Adviser credits as well as Commercial Pesticide Applicator recertification in categories 1A (weeds), 1B (insects), 1C (crop diseases), 4 (seed treatment) and 10 (research and demonstration.)

To register online for this event or for more information, visit the AEP Web site at Registration is $185. After November 20, registration increases to $235. Enrollment is limited and no registrations will be accepted at the door.



Brent Pringnitz is the coordinator of the Iowa State University Extension Agribusiness Education Program. He can be reached at 515/294-9487 or by email at

ISU Extension Offers 2009 Ag Chemical Dealer Updates

By Brent Pringnitz, Agribusiness Education Program

Updates on the latest crop production products and recommendations are the featured topics of the 2009 Ag Chemical Dealer Update Series. Sponsored by Iowa State University Extension, this series will be held Nov. 24 to Dec. 16 at eight locations around Iowa.

These meetings are an excellent opportunity for ag input dealers to meet with extension specialists to review current research, discuss new products and learn of new recommendations.

Each location will feature presentations on weed, insect and crop disease management, as well as soil nutrient management. Each meeting is approved for Certified Crop Adviser (CCA) credits. The meetings offer recertification for Iowa Commercial Pesticide Applicators in categories 1A, 1B, 1C and 10. Recertification is included in meeting registration.

For more information about a particular program, contact the host listed below. Online registration materials and additional information about the meetings are available at An early registration discount is offered to participants who sign up a week or more before the program date.

Program dates, locations and facilitators are:
Nov. 24 -  Waterloo, George Cummins, (641) 228-1453,

Nov. 24 - Calmar, Brian Lang, (563) 382-2949,

Dec. 7 - Lewis, Kyle Jensen, (712) 769-2600,

Dec. 8 -  Mason City, George Cummins, (641) 228-1453,

Dec. 9 - Storm Lake, Paul Kassel,  (712) 262-2264,, and  Mark Licht, (712) 792-2364,

Dec. 10 -  Creston,  Aaron Saeugling,  (641) 782-8426,, and Mark Carlton, (641) 932-5612,

Dec. 14 -  Iowa City, Jim Fawcett, (319) 337-2145,, and Virgil Schmitt, (563) 263-5701,

Dec. 16 -  Ames, John Holmes, (515) 532-3453,, and Mark Wuebker, (515) 957-5778,


Brent A. Pringnitz is the coordinator of the Iowa State University Extension Agribusiness Education Program. He can be reached at 515/294-9487 or by email at

2009 Corn Quality Issues

By Charles Hurburgh, Department of Agricultural and Biosystems Engineering; Roger Elmore, Department of Agronomy

The state experienced a hard freeze Oct. 10 and 11, ending a growing season that had been slowed by rain and, in some areas snow. Despite the overall cool growing season – highlighted by a warm period in early September – the USDA October yield estimate of 186 bushels per acre in Iowa is the highest on record. As often happens with high grain yields, quality issues are surfacing. This article summarizes current field conditions, looks at test weight, weight shrink, and corn storability; two other articles in this series discuss field molds and storage management.

A cool, long growing season will often result in high yields with high grain moistures and low test weights. The lower test weight is the result of more starch and lower protein on a relative basis, a condition that also reduces field dry down rates and increases drying costs. The quick burst of heat in September moved many crops, especially in the western half of the state, to maturity at the further expense of some grain fill and test weight. 

East of Interstate 35, corn ranges from the low 20s to mid 30s moisture. Some corn was frost-damaged at the half to three-quarter milk line. This corn will be low test weight (likely below 50 lb/Bu) with all the characteristics associated with low test weight (see below).  Frost Damage to Corn and Soybeans, PM1635 has more specific information on frost damage to corn and soybeans. 

Corn that has not dried early in the harvest period often stops at 17 to 18 percent. In 2008, this was in the 20-22 percent range. With the number of favorable drying hours much fewer after Oct. 20, attention needs to be given to stalk health. Producers may have to harvest wetter corn first if it is lodging.

Expect drying to cost about five cents per point of moisture removed. Eight points removed, down to 15 percent moisture, would cost about 40 cents per bushel plus the weight shrink. For this reason, there will be an incentive to hold corn at higher moistures, awaiting better drying conditions in the spring, blending opportunities, or higher moisture feeding. However, experiences from 2008 demonstrated the high risk  doing this, particularly when test weights are below 54 pounds per bushel (lb/Bu) after drying.  

Test weight
Test weight is expressed as pounds per volumetric bushel. Corn test weights can range from 45 to over 60 pounds per bushel. The market standard is 54 pounds per bushel, the grade limit for No. 2 Yellow corn. Kernel size, shape, and density all affect test weight.

Higher test weights mean better filled kernels with a higher percentage of hard endosperm. Low test weights frequently imply that the crop did not mature entirely or that it was subjected to stress conditions. Dry corn test weights of 52-54 pounds per bushel (compared with the more typical 55-57 pounds per bushel) are indicative of incomplete maturity.

Food processors are sensitive to lower test weight. Product yield and quality is reduced. Ethanol processors may not be greatly affected by lower test weight this year; lower protein and higher starch yields more ethanol, but does reduce DDGS quality. Most ethanol plants stop taking corn at either 17 or 18 percent, and generally reject corn about 10 percent damage. The feed value on a weight, not volume, basis of low test weight corn is nearly equal to normal corn. Light corn will break more easily and create more fines in storage.

Weight Shrink
Higher valued corn and higher moisture have increased the importance of shrink calculations.  Regardless of the grain and starting moisture, the water shrink, per percentage point of moisture, will always be 100/(100-target moisture).  The market targets are normally 15 percent for corn and 13 percent for soybeans which leads to 1.17 and 1.15 percent shrink per point respectively. Any additional deduction in the market shrink calculation is an allowance for material handling losses. 

For example, a corn shrink of 1.4 percent per point gives about 0.22 percent per point for handling loss.  Typically a commercial elevator experiences about 1 percent overall handling loss and a good farm system about 0.5 percent overall handling loss. This does not include weight loss from spoilage if grain goes out of condition. About 0.5 percent of the weight is lost for every 3 percentage points increase (e.g. from 3 percent to 6 percent) in damage.

Accurate moisture tests are also needed to make shrink calculations work well. Check farm meters on 10-15 samples against the State-inspected meter at the local elevator, or the readings from an Official USDA grain inspector (see list of locations).

Grain elevators must post their shrink factors as the sum of water plus handling loss. Shrink calculations are important for warehouse receipts, loans, proven yield calculations, and inventory estimates. The general principle is to use a shrink rate that gives a reasonable estimate of the actual grain weight remaining after drying and handling operations. Consider the costs of drying, aeration and storage separately from weight shrink.

Corn Storability
Test weight is a good indicator of corn storability. Corn that is below 54 lb/Bu after drying should not be stored into warm weather and should be dried to less than 15 percent moisture before storage of any duration. Lighter corn also will break more in handling.  

Corn normally gains about 0.25 lb/Bu per percent of moisture removed, more with low temperature drying and less if corn temperatures exceed 150F. We are also learning that corn that has reached 150F or more in drying is more difficult to ferment in ethanol plants. However, corn with test weights below 50 lbs/Bu often increases test weight at a reduced rate, progressively less down to 45 lb/Bu where there may be no increase in test weight at all.

The moisture meters used at elevators also measure test weight. The state of Iowa moisture meter inspection will not check the test weight function; this is done by taking 5-10 samples of varying test weight to an official USDA licensed grain grader (list linked above), and adjusting the meter to match the average of the official tests.

Scout for field mold problems.  If you were in one of the several hail areas, field mold is more likely.  A September ICM News article addresses management of hailed corn.   

Field mold can create toxin and feed value concerns, and marketing problems if the damage is high enough to create discounts.  A separate article in this series addresses mold concerns.

We learned from 2008 that extra cost in additional handling and drying logistics is likely to pay off in terms of avoiding spoilage losses later on. This would not be a good year to take chances that wetter corn will keep and can be absorbed in the spring/summer. See the storage management article in this series for more information.



Charles Hurburgh is a professor of Agricultural and Biosystems . He can be contacted at (515) 294-8629 or by email at Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at or (515) 294-6655.

2009 Corn Quality Issues – Field Molds

By Alison Robertson, Department of Plant Pathology; Roger Elmore, Department of Agronomy; Charles Hurburgh, Department of Agricultural and Biosystems Engineering
Frost Oct. 10 and 11 ended the crop growing season in most parts of the state, at the same time the USDA announced October yield estimates of 186 bushels per acre in Iowa. Although high grain yields are expected, reports of quality issues are surfacing.

Cool wet fall conditions favor the development of ear rots caused by Fusarium spp.  These white or pink ear rots are often found in ear corn stored too wet. Field moistures in the low 20s over a long period can favor growth of these fungi, provided temperatures are warm enough (usually above 45F).  These fungi also can produce several toxins that harmful to people and livestock – vomitoxin, zearalenone, and fumonisin.  Grain with field mold should be tested for mycotoxins before feeding.

Scouting and harvesting fields with disease problems
High moisture conditions favor growth of many ear and stalk rot fungi. Fields should be scouted as soon as possible to determine the extent of disease problems. To minimize losses due to ear rot and increased mycotoxin levels, it is recommended that producers harvest problem fields (greater than 10-15 percent incidence of ear rot) as soon as possible.

The longer the corn remains in the field, the greater the chance of toxin production. The toxins most likely to increase in the field at this time are those associated with Gibberella and Fusarium ear rots - namely vomitoxin, zearalenone and fumonisin.  

Diplodia ear rot is more prevalent this season than in previous years. Although mycotoxins associated with Diplodia ear rot have not been reported in the U.S., grain quality will decrease substantially if the corn is allowed to remain in the field, thus early harvest is also recommended in these fields. 

Adjust harvest equipment to minimize damage to kernels since mold and mycotoxin levels tend to be at greater levels in damaged kernels. Dry (to less than 15 percent moisture) and cool (to less than 45 degrees F) grain as quickly as possible to reduce further mold growth and toxin production.

Elevator operators, especially in eastern Iowa report cases of visible mold damage levels 5 percent and higher. In normal years, overall mold damage levels are generally less than 2 percent in freshly harvested corn. High damage levels in harvested grain create challenges for grain grading, particularly in the harvest rush. Damaged corn sharply reduces the future storage life of the grain.

Storage issues
Storage and harvest management will be particularly important. Field damaged grain, regardless of reason, should not be mixed with good grain. Producers should harvest around water holes, downed grain and immature areas. Do not mix damaged grain with good grain in storage. Regardless of condition, all grain should be aerated immediately to reduce temperature and equalize moisture. 

Field damaged grain will not store beyond the winter months. Maintain 1 to 2 percentage points lower moisture than normal grain (for example, 13 percent corn instead of more typical 15 percent).  Do not try to hold field damaged corn at higher moistures to avoid drying expense. If you suspect mycotoxin problems, check with crop insurance providers to see if adjustments may be needed, and how to represent the areas to be adjusted. Your veterinarian or the local USDA grain inspection service provider can assist with obtaining mycotoxin testing. Crop adjustments for quality problems, including mycotoxins, must be done on standing corn at or before harvest.

Accurate grading of field-damaged grain is always difficult in the rush of harvest. Expect end users, such as ethanol plants, to increase their level of grading because mold and weather damage reduce processing yields/byproduct quality.

An Official USDA grade is the standard against which buyer analysis should be compared. It is important that company graders be trained to match USDA graders. Alternatively, samples can be submitted to USDA grading agencies but this process is slower and more costly. In the event of a dispute, use an Official grader. The variety of damage types will be very challenging to evaluate. You can locate the official agency in your area from the USDA list of official inspection and/or weighing services.

Livestock Feed Issues
Livestock (swine, cattle, horses, poultry) are susceptible to certain mycotoxins. Therefore any grain that is fed to livestock should be tested for mycotoxins. Dairy producers should be particularly sensitive to mycotoxins. (See tables below.)

The wide variety of molds has created a range of mycotoxin possibilities – primarily vomitoxin, zearalenone and fumonisin. Prolonged cloudy, humid weather encourages production of the fusarium-based toxins. 

Veterinarians can submit samples to the Iowa State Veterinary Diagnostic Lab. Alternatively, Official USDA grading agencies can do quick tests for these toxins. Toxins concentrate in the distillers grains three to four times the levels in the corn. Ethanol plants are doing quick screening tests on inbound grain, especially on low test weight corn (less than 50 lb/Bu). 

Please see ISU Extension publications  Aflatoxins in Corn - PM1800, and Corn Ear Rots, Storage Molds, Mycotoxins, and Animal Health - PM 1698, for guidelines on sampling and sample handling. The black light test will not detect infection by Fusarium spp.  

fumonisin charts 

Additional Articles
• The USDA – GIPSA – Grain Fungal Diseases & Mycotoxin Reference – Sept 2006 has additional information regarding Vomitoxin and Fumonisum; the FDA – Compliance Program Guidance Manual – 7371.003 – Dec 2005 contains the reference Guidance for Fumonisins in Animal Feeds .
• 2009 Corn Quality IssuesHurburgh, Elmore
• 2009 Corn Quality Issues - Storage ManagementHurburgh, Elmore



Alison Robertson is an assistant professor of plant pathology with research and extension responsibilities in field crop diseases. Robertson may be reached at (515) 294-6708 or by email at Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at or (515) 294-6655. Charles Hurburgh is a professor of Agricultural and Biosystems . He can be contacted at (515) 294-8629 or by email at

2009 Corn Quality Issues – Storage Management

By Charles Hurburgh, Department of Agricultural and Biosystems Engineering; Roger Elmore, Department of Agronomy

It looks like we will have another large wet crop, especially in eastern Iowa. There is less room to accommodate problems from this year because the grain market system is already overloaded with poor quality corn from 2008 crop.  However, we learned from 2008 – extra cost in additional handling and drying logistics is likely to pay off in terms of avoiding spoilage losses later on. This would not be a good year to take chances that wetter corn will keep and can be absorbed in the spring/summer.

Storage Management
Grains have a shelf life just like any food product. Shelf life is primarily determined by moisture content and temperature. It is gradually used through the time before use, and each operation or storage regime consumes a portion of the life.  The table below gives the storage life for corn and soybeans at varying moistures and temperatures.

maximum storage time

Some cautions in using the Table:
1.  The numbers assume that temperatures are held constant – such as with aeration.  Grain heats when it spoils, and gives off moisture. Unaerated grain will shorten its own shelf life through moisture and heat.

2.  Lower test weight corn will spoil faster than the Table indicates. In 2008 the storage times were about half of those expected.

3.  If corn is held at higher moisture then dried, the storage time can be used up by the wet conditions. The dry corn will still experience hot spots or other problems in the summer. This was common for the 2008 crop.

Every action taken after harvest affects the ultimate length of time grain can be stored and the quality at the time of use. Check combine settings between fields for fines and cracked kernels. Fines and cracked kernels spoil much faster than whole, sound kernels. Grain that starts to heat or get moldy has essentially used its storage life. The goal of grain storage management is to reduce the rate at which the life is lost. Always get grain cool quickly and minimize variations both from the dryer and from the field.

Always get wet corn into an aerated storage immediately. Holding wet grain, especially without aeration, shortens shelf life considerably. Fungi grow very fast in corn above 20 percent moisture. Overnight storage of wet corn in a wagon or truck can have a marked effect on future storability. Likewise the practice of holding medium moisture corn (16-20 percent) for future blending or feeding opportunities will cause problems for corn stored (even after drying) into the following summer. 

Aeration Practice
Phase 1: Fall Cool Down
   • Lower grain temperatures stepwise
         • October 40-45 F
         • November 35-40 F
         • December 28-35 F

Phase 2: Winter Maintenance
   • Maintain temperatures with intermittent aeration
         • January, February 28-35 F

Phase 3: Spring Holding
   • Keep cold grain cold
         • Seal fans
         • Ventilate headspace intermittently

 Wet corn should be checked weekly, and monitored for temperature increases. Wet corn should have 0.2 cfm/bu of well-distributed aeration, double the normal rates for dry corn. Problems will start to show up in February and March as temperatures rise. Wet corn should not be held in bunkers, piles, flat storages, sheds or other structures where airflow is not well distributed.

 Options when wet corn volume exceeds drying capacity
1) Dry to 17-18 percent moisture and cool in the storage bin. Corn will end up at about 16 percent moisture. Good aeration should be able to manage 16 percent corn down to the 14 percent needed for midsummer storage.

2) Dry to 20 percent moisture, cool in bin, hold wet corn for spring but not summer.

3)  Dry in two passes – first down to 17-19 percent, then the rest of drying later after the actual harvest is over. This requires more handling and logistics, but could be profitable if  the market carry increases to encourage storage. Last summer, 16-19 percent moisture corn was still coming to market, in poor condition. This corn could have been dried, albeit at additional cost and effort.

The less you dry, the more risk you are accepting. But spreading out the drying into spring may be the only choice. Risk will require more constant attention.

Be selective about what corn is placed in storage versus moved at harvest. Deliberately decide which corn and bins are going to be kept into the summer. This should be your best (highest test weight) corn, harvested below 20 percent moisture with careful combine settings to minimize trash and placed in storages with good aeration rates/airflow distributions.

Low test weight corn should not be put in temporary storages or outdoor piles. It is also not wise to mix corn of different crop years in the same storage bin; the mix is less stable than each year’s crop stored separately. The 2008 corn was very susceptible to mold and heating in storage; 2009 crop looks to be similar. Holding wetter corn should be done with a plan for drying or other options to halt spoilage if it starts.

Remove the center core and use a grain distributor if possible. Check your grain at least every two weeks, with some way to take grain temperatures. If a slow rise is noted, aerate. If a hot spot starts, make that the next corn to be moved out; one storage problem always leads to another.

Understand your buyers' needs, and match storage and drying practice to intended marketing time. For example, corn presold for July or August delivery should be dried more fully right away.


Other articles in this series
2009 Corn Quality Issues - Hurburgh, Elmore
2009 Corn Quality Issues - Field Molds - Robertson, Elmore, Hurburgh



Charles Hurburgh is a professor of Agricultural and Biosystems . He can be contacted at (515) 294- or by email at Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at or (515) 294-6655.

Crop and Weather Report October 12

By Doug Cooper, Extension Communications

During this week’s crop and weather report, ISU Extension climatologist Elwynn Taylor, integrated pest management specialist Rich Pope, and corn agronomist Roger Elmore discuss how the hard freeze coupled with delayed harvest is raising concerns about crop quality.

Taylor comments on the Oct. 9 crop production report released by USDA predicting 188 bushels of corn per acre, which is based on the weight of the ears and ear count per acre. He says the report assumes normal weather from mid September to harvest time, but we haven’t had normal weather.

Elmore has received early harvest reports that are very positive, with a few reports of lighter test weights and lower yields. He feels the USDA prediction of 188 bushels per acre sounds very optimistic.

Field agronomists haven’t seen much field work over the weekend, according to Pope. They report 35 percent of corn and 5 percent of soybeans harvested, with frequent comments about stalk rots.


This article was published originally on 10/19/2009 The information contained within the article may or may not be up to date depending on when you are accessing the information.

Links to this material are strongly encouraged. This article may be republished without further permission if it is published as written and includes credit to the author, Integrated Crop Management News and Iowa State University Extension. Prior permission from the author is required if this article is republished in any other manner.