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9/14/2009 - 9/20/2009

Hail Damage – Grain Quality Survey

By Bill Arndorfer, Extension field agronomist; Alison Robertson and Gary Munkvold, Department of Plant Pathology; Charlie Hurburgh, Department of Ag and Biosystems Engineering; and Steve Ensley, Vet Medicine

There were two major hail events this summer during grain fill that resulted in significant corn crop damage in the path of the storm. The damage occurred over several thousand acres with some fields being a total loss and other fields having varying degrees of damage. This resulted in several crop hail damage meetings across the state to help farmers make informed harvest decisions. A common question from farmers and grain merchandisers dealt with grain quality issues. Specifically, what impact will the hail damage have on grain quality, ear rot severity and mycotoxin contamination in my corn crop? 

To help answer this question, ISU Extension will be conducting a survey to assess the impact of hail damage on ear rot severity, mycotoxin contamination and grain quality in corn.  Iowa State University plant pathologists Alison Robertson and Gary Munkvold along with Charles Hurburgh, Professor in Charge of Iowa Grain Quality Initiative are looking for fields that were damaged by hail this past summer to be included in this survey. The following information is required in order to be a part of the study: field location with GPS coordinates or section and township, hybrid involved, date of the hail storm, size of hail stones, duration of the storm, percent damage to the crop, growth stage of the crop at the time of the hail damage and whether fungicides were applied. To participate in this survey, first identify hail damaged corn fields, and then notify Bill Arndorfer at: of intent to participate.

In order to further assess the impact of fungicide application on hail damaged corn, fields that have an untreated strip check should have ear samples taken from both the treated and untreated areas of the field. If an undamaged field of the same hybrid occurs nearby, then ear samples from the undamaged and damaged fields are encouraged.

A representative sample from each identified field (or strip in the case of fungicide application) should include twenty four ears collected from eight locations that are at least twenty five paces apart. The husks on the ear must not be peeled back or removed. The ear samples should be sent by overnight mail to:

Hail Damage Grain Quality Survey
351 Bessey Hall
Ames, IA 50014. 

If possible, a digital photo of the area of the field from which the ears were sampled should be emailed to Bill Arndorfer.

For each field sample submitted a report of ear rot prevalence and severity, mycotoxin levels and grain quality characteristics of each sample, will be prepared and e-mailed to the person submitting the sample.



Bill Arndorfer is an Extension field agronomist assigned to special projects. He can be reached at (319)234-6811 or by emailing Alison Robertson is an assistant professor of plant pathology with research and extension responsibilities in field crop diseases. She can be reached at (515) 294-6708 or by email at Gary Munkvold is an associate professor of plant pathology and seed science endowed chair in the Iowa State University Seed Science Center with research and teaching responsibilities in seed pathology. He can be reached at (515) 294-7560 or by email at Charles Hurburgh is a professor of Agricultural and Biosystems. He can be contacted at (515) 294- or by email at Steve Ensley is a Vet Diagnostic and Production Animal Medicine clinician. He can be reached at (515) 294-1950 or by email at

Degree Days - Slow and Steady Wins the Race

By Rich Pope, Department of Plant Pathology

Soybean fields are now starting to senesce, and corn is filling well. The latest USDA crop forecast projected a 187 bushel per acre average for corn yields, and 52 bushels per acre for the beans. Both would be great accomplishments considering the wet spring and cool summer. As of Sept. 13, we are lagging for the season an "average" accumulation of between 300 and 400 degree days, which rivals the 1992 growing season.

Accumulated degree days from May 1 through September 13, 2009

Average temperatures and clear, sunny days the next two to three weeks are still the ideal for Iowa crops. Soybean aphids are still persisting with sizeable populations in some fields, but in Ames we are seeing winged aphids fully engaged in the migration to buckthorn for overwintering.  Nearly all soybeans well past the point of gaining benefit from treatment to control aphids.

Regardless of how the season finishes, wet grain, especially corn, is highly likely. That is all the more reason to ensure harvest equipment is properly adjusted and that grain is handled properly during and after binning.



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

Studying Stover Harvest Effects on Yield, Soil, Climate

By Mahdi Al-Kaisi, John Sawyer and Antonio Mallarino, Department of Agronomy

Corn stover has been used for many years as bedding and food for livestock, as well as to nourish and protect soils. In recent years, the ubiquitous stalk, leaf and cob residue of corn plants left in fields after harvest has found a new market: as a potential source for cellulosic ethanol production.

But harvesting the stover – which, when left in place, halts erosion and supplies vital nutrients back to the soil – could have unintended consequences, from lowering the fertility of fields to affecting productivity, soil and water quality and even climate. A comprehensive new study by Iowa State University agronomy researchers may soon shed light on these questions.

Last fall, Mahdi Al-Kaisi, ISU Extension soil management specialist, and ISU Extension soil fertility colleagues John Sawyer and Antonio Mallarino, started a three-year study looking at how removing residue at different rates affects soil productivity, nutrient cycling and greenhouse gas emissions in no-till and chisel-plow fields. They also want to find the optimal nitrogen, phosphorus and potassium fertilization rates needed to supplement nutrients lost from residue removal. The research is funded by the ISU agronomy department.

“There’s not any research integrating these questions the way Iowa State is doing it,” Al-Kaisi said. “The impacts of large-scale corn stover removal on the soil, sustainability of crop production and environmental conservation are not well-known.

“A diverse research-based effort integrating these questions could provide information needed to successfully use biomass production for energy and livestock in Iowa.”

The study was set in motion after harvest last fall on continuous corn fields at ISU’s Armstrong Research and Demonstration Farm near Lewis, and the ISU Bruner Research Farm west of Ames. Residue was removed at three rates (0, 50 or 100 percent) on both the no-till and chisel-plowed plots.

Residue samples were analyzed for initial nutrient content and the fields were left to sit until this spring, when six nitrogen rates ranging from 0 to 250 pounds per acre were added to the plots after planting. A regular daily and weekly regimen of soil testing started soon after.

Soil productivity
For future viability of broad-scale stover harvest, fields need to remain productive. This fall, researchers will get initial yield results from the various treatments and measure nutrient uptake in the leftover residue.

Productivity is highly linked to available nutrients – which in turn can affect soil structure, another key factor in yields. “Corn stover residue is a good source of carbon into the soil organic matter. If you continue to harvest residue, you are removing a significant portion of the carbon input to the soil,” Al-Kaisi said.

How stover removal alters nutrient cycling – the second major component of the research – is integral to the yield question.

Nutrient cycling
“The amount of nutrients in the residue will depend on the fertility program farmers use during the growing season,” Al-Kaisi said. “A well-managed field with optimum nutrient supply will have healthy plants – and good grain production. This would reflect in the amount of nutrients left in the stalks after harvest.”

Seeing how recycling of nutrients back to the soil is altered by stover removal is the broad aim of this angle.

Throughout the spring and summer, ISU agronomy graduate student Jose Guzman has been testing a range of soil indicators, from levels of organic carbon, nitrogen and other nutrients to water infiltration, microbial biomass and emissions of carbon dioxide (CO2) and nitrous oxide (N2O), two key greenhouse gases.

“Soil temperature and moisture are huge factors in the decomposition of stover,” Guzman said. “Every hour, in-field sensors capture soil temperature data, and every day someone tests soil moisture. We’ll capture these all year and might try to use this data to make a model to predict decomposition rates.”

Monitoring greenhouse gases
Determining environmental effects of stover harvest is the third key aim of the research. “We want to see how agricultural practices can sequester more CO2 and minimize N2O emissions,” Al-Kaisi said.

The interaction between corn residue removal, soil nutrient retention and greenhouse gas emissions is complex. But as Al-Kaisi explains, large-scale stover removal has the potential to change soil chemistry and dynamics so more gases are released to the atmosphere instead of locked within the soil.

Continuous corn fields also require more nitrogen, which can further skew the soil chemistry and increase the risk of N2O emissions. “That’s why we’re using six nitrogen rates, to see what’s the optimum rate to minimize emissions yet have profitable corn production,” Al-Kaisi said.

To monitor these changes, Guzman tests emissions on a weekly basis. With the sun high overhead, he strides into a field of corn taller than his head toting a CO2 sampling machine that looks part portable vacuum cleaner, part old transistor radio with a flexible suction hose.

Crouching in the sun-dappled shadows under the corn stalks, Guzman attaches the hose to a PVC pipe buried in the soil and explains the significance of the CO2 reading.

“We’re keeping track of how much carbon we’re putting in and how much we’re losing,” he said. “Carbon helps retain other nutrients in the soil. If farmers manage for carbon, they will have very healthy soils – which will help productivity.”

Initial results of the research will be available later this fall. Researchers ultimately hope to use the data to help farmers, agronomists and policy-makers make sound economic and environmental decisions about stover use.

“We need to strike a balance between economic viability and the bottom line of farmers, and environmental consequences,” Al-Kaisi said. “We have good soil in Iowa, and we want to keep it this way if we want to keep our high productivity.”



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. John Sawyer and Antonio Mallarino are professors of agronomy, both with research and extension responsibilities in soil fertility and nutrient management. Sawyer can be reached at or by calling (515) 294-7078. Mallarino can be reached at or by calling (515) 294-6200.

This article was written by Tamsyn Jones, ISU Corn and Soybean Initiative communications specialist and distributed by the College of Agriculture and Life Sciences.


2009 Crop Year is Mirror Image of 2008

By Chad Hart, Department of Economics

The parallels between the 2009 crop season and the 2008 crop season are striking. This summer is closing out much like last summer for crops. The early season concern about delayed planting and crop progress is fading under steady doses of sunshine and timely rains. And with crop conditions holding, crop production is up and prices have worked their way down.
Long-range weather forecasts point to a continuation for the rest of the growing season of the relatively mild weather conditions most of the Midwest has enjoyed. While the crops are still behind usual development pace, this looks to be a long growing season that will allow many crop areas to catch up.
That means another year of large supplies. Where will all that corn and soybean go? One market is livestock feed. The livestock industry continues to work through financial difficulties. While feed demand projections are still lower than in previous years, the decline is projected to halt this year.
Another traditional market is biofuels. Crop demand growth via biofuels has slowed as the biofuel industries move through a consolidation phase. Biofuel data from the first few months of 2009 show the ethanol industry is continuing to grow, just at a slower rate than before, while biodiesel production is behind last year’s pace.
Exports have been the bright spot. Soybean exports from the 2008 crop are on record pace, and U.S. Department of Agriculture’s projections for the 2009 crop point to higher corn and strong soybean exports.
While demand has been weakening, lower crop prices could help spur a reversal in that trend. Lower corn and soybean prices imply lower production costs for livestock and biofuels, and that can help the bottom line in those sectors. 
But for now, the markets will concentrate on the supply picture, with the overall economic situation providing some secondary shifts. Seasonal pricing patterns also have returned to the crop markets.
Corn and soybean prices tend to be at their highest in the late spring and early summer, decline through the harvest, and rebound over the winter and early spring. Current weather and crop patterns are supporting these seasonal trends.
The best pre-harvest marketing opportunities have likely passed. But the seasonal pattern suggests that for those who can store the crop, higher prices can be found a few months after harvest. The mid-September USDA reports confirmed large corn and soybean crops, but also provided signs of demand strength. These continuing signs of demand strength will be critical to maintaining prices.
The outlook for higher prices is supported by positive signs in the general economy. Prospects for some recovery on the general economic front in late 2009 or 2010 point to the possibility of increased crop demand later in the marketing year. Oil futures prices for late 2009 and early 2010 are holding above $70 per barrel, implying some strength in energy demand. And for soybeans, early export sales on the 2009 crop have exceeded the pace set in previous years.


Chad Hart is the Iowa State University grain marketing economist. He can be reached at (515) 294-9911 or

Crop and Weather Report – September 14

By Doug Cooper, Extension Communications specialist

Guests for the weekly crop and weather report Sept. 14 are ISU Extension climatologist Elwynn Taylor, integrated pest management specialist Rich Pope and corn agronomist Roger Elmore.

With harvest is just around the corner, Taylor says an arctic cold front is heading into the U.S. from Canada, and he doesn't think it will have any significant impact on Iowa. Mason City is the furthest behind in growing degrees days from normal of any site measured in the Corn Belt.

Pope repeats his message from prior weeks - keep scouting fields as harvest draws closer. Soybean aphids are still being found in patches in some fields, though they are beginning to migrate to buckthorn for overwintering. Bright sunshiny days have been beneficial to crops.

Elmore says we are one to two weeks to maturity in most parts of the state. He discusses some issues of concern across the state - corn senescing fast, bottom up and top down, all seems a little bit early; some drought and nitrogen pressure; and disease pressure which is increasing with the cool nights and the morning fogs.

Fall Cutting Management for Alfalfa

By Steve Barnhart, Department of Agronomy

Rainfall throughout the growing season put most alfalfa producers behind two to three weeks for their first, and correspondingly their second, third, and sometimes forth cuttings. Now in mid-September, producers are trying to decide on their remaining fall harvest options and the possible impact on winter survival of the stands.

The goal is to help keep the forage plants ‘perennial’
During the fall weeks, perennial forage legumes and grasses respond to shortening days and cooling average daily temperatures and progress through their gradual “cold hardening” process. The genetics of the variety determines how cold tolerant the plant crown and taproot can be during the winter months. Most successfully winter hardened alfalfa plants can withstand soil temperatures in the crown area to about 0 to 4 degrees F without crown tissue damage. At lower soil and crown temperatures, varieties and individual plants will vary in the degree of cold damage they may experience.

To acquire their potential for winter survival, alfalfa plants should get five to six weeks of uninterrupted growth to accumulate root carbohydrates and proteins before going dormant for the winter. A killing freeze, or the temperature that will stop further top growth for the season, is about 23 to 24 degrees F for several hours. So it is important to manage fall harvests to give the plants the best chance for strong winter survival.
Fall cutting management strategies
There are several things to consider if your alfalfa is knee high in mid-September and you are questioning whether to cut it. The first thing to consider is whether the field will be hay next year or not. If not, cut the alfalfa anytime. If it will be hay again next year, consider whether or not you need the hay. If not, then leave the last growth in the field – don’t graze in fall or winter. On the other hand, if you do need the hay it is best to wait until at or after the killing freeze (23 to 24 degrees F) to cut. Then leave a five to six inch stubble.

Some producers may hesitate to do this because it if move difficult to dry hay in October, but the risk of winter injury to the field necessitates the wait. If you cut in mid-September, the plants will begin to regrow and begin to use what stored carbohydrates they have. The risk comes if this late growth leaves the plants with a relatively low level of available root stores when the killing freeze comes. Low levels of winter root stores may lead to a greater susceptibility to winter cold injury and to a delayed spring recovery.

Review this checklist to see how your summer and fall management has been relative to alfalfa stand vigor and overwintering potential.
These factors improve alfalfa winter survival:
• 4 inches or more of winter-long snow cover will help
• winter tolerant variety
• 2 or 3 summer cut harvest systems with good regrowth between cuttings
• 5 to 6 weeks of uninterrupted growth during September and October
• all of the last growth of the season left in the field (no cutting or grazing)
• if a late fall cut was taken or grazed, a 5 to 6 inch stubble was left 
• management of insects (potato leafhoppers) during the growing season   
• good levels of  available potassium in the soil
• young stands – or older stands with no root or crown disease

Steve Barnhart is a professor of agronomy with extension, teaching, and research responsibilities in forage production and management. Barnhart can be contacted at (515) 294-7835 or by email


This article was published originally on 8/18/2009 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.

Approaching Hessian Fly-free Dates in Iowa

By Erin Hodgson, Department of Entomology

The Hessian fly (Fig.1) can be a destructive pest in wheat, although there haven't been many reports of this pest in recent Iowa history. Typically, resistant wheat varieties provide sufficient protection against the Hessian fly and growers do not have to adjust planting dates to avoid adult emergence. There are genetic biotypes that can attack resistant fields, and so monitoring for Hessian fly is recommended for wheat growers.

hessian fly

Figure 1. Although not a common pest, growers should monitor for plant damage.


Life cycle. The Hessian fly has two generations per year in Iowa. They overwinter as a resting pupae, often referred to as a "flaxseed" because of the resemblance (Fig. 2). Adults emerge as volunteer spring wheat and early-seeded winter wheat starts to grow. Females lay about 300 eggs in four days. Although wheat is the preferred host plant, they will also deposit eggs in barley and rye. The eggs are reddish and very small, usually laid end-to-end in small groups on the upper leaf surface. Larvae (maggots) prefer to feed within the grooves of the wheat leaf sheath and stem until they pupate before harvest (Fig. 3). Hessian flies spend the summer as a flaxseed in wheat stubble, and the second generation emerges in the fall to feed on emerging winter wheat.

hessian fly in flax seed stage

Figure 2. Hessian fly pupae are called flaxseeds and can be found at the crown of wheat plants.


hessian fly larvae

Figure 3. Hessian fly larvae are maggots that feed within the leaf sheath and stem.


Damage.  Larvae cause injury to wheat by feeding on leaves, tillers and stems. Hessian flies are considered an economic pest in the fall because they can cause significant damage that can stunt or kill plants. As seed heads begin to fill, heavily infested plants can lodge. High humidity is needed for a significant infestation to develop.

Management.  Once a wheat field is infested with Hessian fly, foliar insecticides will not make contact with feeding larvae. Hessian fly management depends on good crop production practices and preventing infestations. Follow these guidelines to protect yield.

1. Destroy volunteer wheat, especially during wet years, to minimize favorable host plants. Mated females will have difficulty finding suitable hosts for their eggs and further reduce the overwintering population if all the volunteer wheat is removed.

2. Plant a resistant wheat variety to discourage females from depositing eggs.

3. Plant after the fly-free date to ensure emerging plants do not get infested (Fig. 4). Adults are short-lived, so planting after recommended historical dates can improve the overwintering stand conditions.

fly free dates

Figure 4. Predicted Hessian fly-free dates for Iowa.


4. Check areas of the field with poor stands or stunted plants. Examine the base of the plant (first and second nodes) by pulling the leaf sheath away from the stem. Depending on the time of year, look for larvae or flaxseeds.

5. Avoid overuse of nitrogen fertilizers so that wheat plants will not overproduce vegetative growth.

6. Practice crop rotation because the adults are weak fliers and they have a limited host range. 

Portions of this article originally appeared in a previous ICM article.


Erin Hodgson is an assistant professor of entomology with extension and research responsibilities. She can be contacted by email at or phone (515) 294-2847.

This article was published originally on 9/21/2009 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.