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11/16/2009 - 11/22/2009

A Tough Harvest - Frequently Asked Questions, Update

By Charles Hurburgh, Department Agricultural and Biosystems Engineering

Iowa was very fortunate to receive two weeks of warmer than normal weather, and more importantly lower than expected humidity in the air. This has allowed soybean harvest to be nearly completed, and rapid progress to be made on corn harvest, with moistures now in the low 20s and upper teens. The eastern and far northern Corn Belt still have much wetter corn in the field. New problems have arisen, and efforts now turn to conditioning grain for storage.


Reports of field mold, and most recently toxins, are coming in; how serious is this?
The warmer weather which was a huge help in field drydown also kept fungi alive and growing. In most of Iowa, where corn moistures were below 25 percent, the mold is relatively benign cladisporium, identified by black dots on the kernel surface. Some will be knocked off in harvest and handling. These kernels will grade Damage, but generally do not produce toxins. 

The white or pink molds, Gibberella and Fusarium, can produce toxins – vomitoxin, zearalenone, fumonisin.  These fungi have been reported more in eastern Corn Belt, and toxins above advisory levels have been found.  Two October ICM articles provide additional information on molds, toxins and feeding advice – How Delayed Harvest Might Affect Ear Rots and Mycotoxin Contamination  and 2009 Corn Quality Issues – Field Molds.

Toxins concentrate at 3 to1 ratio in the distillers grains for ethanol plants.  Most plants and many elevators are screening. There are two options for screening  when using strip test kits; slow down receiving to 10-15 minutes per truck so that each load can be tested, or periodically test a composite of the grain received, preferably by bin assignment, during that period.  The second is preferred for time reasons, and will give a reasonable assessment of the average quality received. If problems show up, more intensive sampling of visually suspect loads can be done. Random spot checks of individual loads run the risk of either over or understating the problem. Likewise testing of only visually moldy loads can be misleading; toxin is possible without significant visual signs. The composite approach is more able to create the over five-pound sample that must be ground in preparation for using any mycotoxin test method.

Be sure to contact your crop insurance agent if you have field mold, or were told by a buyer that you do; toxins and quality are covered by crop insurance but the adjustment must be done in the field.  Adjustment of check strips should be done as close in time to harvest of the field as possible. Likewise, if pre-harvest field samples are taken, harvest immediately to prevent changes after the adjustment.

Toxins are not often a storage problem but with very high moisture and heating, they can be formed. End users should test moldy high moisture corn and such corn after it has been dried, for the full range of toxins, especially if the corn has heated in storage. 

I feed my own corn; what steps should I take?
• Scout your fields.
• Try not to feed moldy corn.
• Do not mix moldy and clean corn in the same bin.
• Dry and sell the moldy corn quickly.
• Take a representative sample of each of your bins to a lab, or to your veterinarian to send to the Iowa State Vet Diagnostic Lab. 
• Read the guidelines carefully (see above links); they give recommendations in parts per million (ppm) for individual ingredients and a maximum inclusion rate of the ingredient in the feed.  For example, 5 ppm maximum for corn with a 20 percent inclusion rate of the suspect corn for swine. 
• Be careful of additive effects if you have two sources of toxin, such as corn and distillers grains, to not exceed the total ration limits.
• Work with your veterinarian and nutritionist in feeding this corn.

I have very wet corn in storage; now what?
• If the corn is below 20 percent, natural air/low temperature drying can handle it.  Low volume aeration only will cool the grain but plan to move it during the winter or dry later. Corn wetter than 20 percent at this time will have to be dried further; it should not be in piles or other places that are hard to aerate and complicated to pick up.
• Maintain continuous airflow, and steadily move this corn to heated air drying regardless of the logistics required to do so.
• Check very often so that grain which is noticeably heating and crusting can be moved/turned.
• Expect to lose some of this corn to mold through both physical shrink and damaged kernels if you cannot dry it quickly. Wet corn in piles and bunkers is especially high risk. 
• The 2009 crop corn is low in test weight, which means that its storage properties are poor. Choose which corn to move first according to test weight, lowest first. 

What are the most important things to do for medium moisture and dry grains in storage?
Remove the center core of bins and re-level. Be able to monitor temperature and progressively drop the temperature as the outside air temperatures fall. All grain should get to 35F or lower; it is ok to freeze corn as long the grain is clean so that chunks do not form. Cold grain needs headspace ventilation fans to control condensation in the spring.


Charles Hurburgh is a professor of Agricultural and Biosystems . He can be contacted at (515) 294-8629 or by email at

Degree Days - What a Year It Was

By Rich Pope, Department of Plant Pathology

Heat or maybe lack of heat is a better description to use in this recap of the growing season. The degree day departure from average graphic shows how the season progressed by crop reporting district.

degree day graph

This year, the state was remarkably consistent in the heat that accumulated, with northwest and central Iowa faring just slightly better then the rest of the state. July, late August, and October were all very cold compared with historical records, with July ranking as the coldest on record, and October in the coldest five.


For most of Iowa, rainfall throughout the season was pretty average, with the slight exception in the east central and southeast districts, where rainfall was a bit above normal from July on.

rainfall graph

There were some very localized exceptions associated with summer thunderstorms that brought locally heavy rain to small areas.  Two of those storms were notable, because of devastating hail that destroyed crops and caused other damage. The first, on July 24, cut a swath from about Calmar in Winnesheik County to western Dubuque County.  The second was a remarkable storm that stripped crops from Ida County to Grundy County, and caused particularly intense damage in Hardin County near Eldora and near Callendar in Webster and Calhoun Counties.  This August 10 storm was unusual in that it formed and persisted across Iowa in the mid to late morning, associated with a slow moving cold front. 

The two graphics (below) from NASA show an image of the damage from space that was taken on August 23.  Note the defoliation scars that document the extent of these events.  ISU researchers have been analyzing damaged ears from these areas for ear rots and potential mycotoxin formation.


NE hail damage area

July 24, 2009 storm track, northeast Iowa



eldora hail damage

August 10, 2009 storm track, central Iowa


Rich Pope is a program specialist with responsibilities with Integrated Pest Management. Pope can be contacted at or by calling (515) 294-5899.

Soil Management and Environment Website Launched by Extension

By Mahdi Al-Kaisi, Associate Professor, Agronomy Department

Iowa State University Extension soil management and environment information can now be found on a new website  The Soil Management/Einvironment website replaces the Soil Management and Conservation Practices website. It contains information that is useful to producers, agriculture business, and scientists.

Website content is based on past and current extension and research projects on tillage and cropping systems, soil carbon, residue management, and cover crops. ISU Extension publications, newsletter articles, refereed journal articles, and relevant links are listed under each area of interest. Descriptions of the most current projects are also included.

Several management tools are available, including residue and erosion calculators and other decision-making tools. The materials on this website are intended for public use and educational and research purposes with proper credit to the authors and Iowa State University Agronomy Extension. We welcome any feedback on the new format so continued improvements to the dissemination of our extension and research programs to the agricultural community in Iowa and elsewhere can be made.

Mahdi Al-Kaisi is an associate professor in agronomy with research and extension responsibilities in soil management and environmental soil science. He can be reached at or (515) 294-8304.

RUSLE2 and P Index Workshops for Manure and Nutrient Plan Writers Offered by ISU Extension

By Angie Rieck-Hinz, Department of Agronomy

Livestock producers and service providers can receive training on how to use the Revised Universal Soil Loss Equation 2 (RUSLE2) and the Iowa Phosphorus Index for use in nutrient management and manure management plans at workshops being offered by Iowa State University Extension and the Iowa Manure Management Action Group (IMMAG), in collaboration with the Iowa USDA-Natural Resources Conservation Service.

The workshop will be held on Dec. 17 at the Borlaug Learning Center, located on the Northeast Iowa Research and Demonstration Farm near Nashua, Iowa.  The workshop starts at 8:30 a.m. and ends at 4 p.m. It is an introductory level, hands-on workshop that will provide the participant with software orientation.

This workshop will introduce participants to the operating parameters for RUSLE2; selection of input values for RUSLE2; and developing and saving management operations for RUSLE2. In addition, real field examples will be used in the workshop to determine risk calculations of the Iowa Phosphorus Index and how to incorporate these numbers into manure and nutrient management planning requirements.

New for this workshop will be the inclusion of parameters for RUSLE2 and P Index calculations on snow-covered or frozen ground. Soil sampling requirements for manure management plans will also be discussed. 

The cost of the workshop is $160 if registered on or prior to Dec. 10; the fee is $175 for registering after Dec. 10. The workshop fee includes handout materials, refreshments and lunch. Because software will be provided, participants are required to bring a MS Windows compatible laptop equipped with a CD-ROM drive and Microsoft Excel software. Participants must have their administrator password to the computer they bring in order to install software. The workshop is limited to 30 participants.

Registration, program information and directions to the workshop are available on-line. 

Questions regarding these workshops should be directed to Kapil Arora at (515) 382-6551or Angie Rieck-Hinz at (515) 294-9590. 


Angela Rieck-Hinz is an extension program specialist for Iowa State University Extension and is the coordinator of the Iowa Manure Management Action Group (IMMAG). Rieck-Hinz can be reached at (515) 294-9590 or by emailing

This article was published originally on 11/23/2009 The information contained within the article may or may not be up to date depending on when you are accessing the information.

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