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5/3/2010 - 5/9/2010

Iowa State Receives $200,000 Grant to Develop Biomass Crops in Southern Iowa

By Emily Heaton, Department of Agronomy

Iowa State University has been awarded a $200,000 grant to develop perennial cash crops for southern Iowa. The grant was awarded by the U.S. Department of Energy's Sun Grant Initiative to fund biomass crop production research and forms a partnership with the U.S. Department of Agriculture Natural Resources Conservation Service and Agricultural Research Service.

The funds will be used for research and demonstration at Iowa State, Southwestern Community College and for on-farm research. Perennial warm-season grasses may be a much more appropriate crop for farmers in the southern part of the state. Because the soils there are more erodible and less productive for corn, perennials have the potential to be an economical alternative.

Iowa State research will focus on developing establishment practices for Miscanthus, a new biomass crop in Iowa. In addition to replicating some ISU research, faculty and students at Southwestern Community College will compare Miscanthus in field plots alongside native perennial grasses. Improved production of biomass crops is of interest in the area because farmers in northern Missouri and southern Iowa are already producing biomass from grasses for a Missouri cooperative. The harvested biomass is processed into clean-burning pellets that are mixed with coal for electric companies. Biomass production is a response to Missouri’s carbon mandates, which limit emissions from coal-fired power plants.

Mark DePoy, Natural Resource and Conservation Service regional coordinator for the Southern Iowa Research Conservation and Development district, thinks the cooperative model would be a good fit for southern Iowa and profitable, because this part of the state is similar in natural resources and soils to northern Missouri. Acreage dedicated to grass crops would produce cleaner water, improve soil quality and provide ample habitat for wildlife while creating good paying jobs.

The federal government also offers incentives through the Biomass Crop Assistance Program. The program matches each dollar up to $45 a ton that farmers spend to deliver biomass crops for the first two years. The goal of the Iowa State grant project is to create viable systems that protect the land and create a profitable crop for farmers. By helping the farmers make money and protect the soil, we are doing our job.


Emily Heaton is an Iowa State University agronomy professor with extension responsibilities in biomass production. She can be contacted by emailing or calling 515-294-1310.

Temperature Fluctuations Have and May Continue to Inhibit Corn Emergence

By Roger Elmore and Lori Abendroth, Department of Agronomy

Corn planting proceeded at an all-time record this spring. We’ve experienced one of the best planting seasons ever in Iowa. According to the most recent USDA-NASS report (2 May 2010), 84 percent of Iowa’s corn  was planted with cropping districts ranging from 69 percent complete in south central Iowa to 92 percent complete in north central Iowa. Overall, corn has been planted within the recommended window which should serve to maximize yield potential relative to planting date.

Soil and weather conditions at planting and emergence were excellent for most of the state. Alison Robertson recently emphasized the need to assess seedling health when doing stand counts in a May 4, 2010 ICM article in response to some of the problems occurring in southeast Iowa this spring. Seedling emergence problems there are correlated with swings in April soil temperature.

Cooler soil temperatures slow the germination process and predispose seedlings to fungal infection. We have also observed, or heard reports of, seedling growth problems in some parts of Iowa already this year, including:

Imbibitional chilling damage, which is the chilling effect seeds may experience when they imbibe, or absorb, water  when  soil temperatures are less than  55 F for an extended time. Seedlings may “corkscrew” or not emerge when exposed to these cool soil temperatures. This may happen also when there are rapid swings in air temperatures of nearly 30 F.

• Soil crusting due to wet soils at planting or heavy rains after planting reducing plant stands. Significant stand reductions lower yield potential.

• “Leafing out” underground - see Photo 1.This occurs most often in crusted soils and also appears associated with imbibitional chilling, mentioned above.

Variable plant emergence and reduced plant population - see Photo 2. Variable emergence and growth will reduce yield.


Cool Temperatures Soon?
The forecast for the next several days is for air temperatures dropping into the high 30’s at night; soil temperatures will also lower respectively. Growers and agronomists should pay particular attention to corn fields planted recently as they are the most likely to exhibit seedling rot or poorer emergence associated with some of the issues mentioned here. Frost is likely to occur in low lying areas causing leaf necrosis and delayed growth of sprouted seeds. 

Any of the situations mentioned above may result in a need to replant. Assess stands well before making this decision.

Irrespective of all of these issues, 2010 has provided one of the best planting seasons to date.  Most of Iowa’s corn was planted within a timeframe that should serve to maximize yield potential.

emerging corn

Photo 1. Seedling leaved out under soil surface. Story Co. IA, 4 May 2010. Roger Elmore.


emerging corn 2

Photo 2. Variable seedling emergence dates can reduce yields. Story Co. IA, 4 May 2010. Roger Elmore. See additional photos for leaving out underground and variable seedling emergence.



Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. Lori Abendroth is an agronomy specialist with research and extension responsibilities in corn production. Elmore can be contacted by email at or (515) 294-6655; Abendroth can be contacted by email at or (515) 294-5692.

CORRECTION to Alfalfa Weevil Scouting Update 2010

By Adam Sisson, Corn and Soybean Initiative and Erin Hodgson, Department of Entomology

The alfalfa weevil article published on May 3, 2010 in the ISU Extension Integrated Crop Management News included predicted dates for scouting for the alfalfa weevil larvae in Iowa. The article used degree days that were obtained from the web-based climate service Midwestern Regional Climate Center

Following publication of the article, Iowa State University Extension field agronomist Brian Lang noticed that the degree days reported in the article were lower than what he was observing in northeastern Iowa and that degree days reported by ISU Extension field agronomist Virgil Schmitt for the east-central and southeast parts of the state were higher than reported in the article.

The information from Iowa State Extension field agronomists and new data from a cumulative growing degree day map from Oregon State University suggest that all of the crop reporting districts in Iowa have surpassed the scouting threshold for alfalfa weevil and that growers should presently be looking for the insect in fields. 

We apologize for any confusion.


Adam Sisson is a program assistant with responsibilities with the Corn and Soybean Initiative. Sisson can be contacted by email at or by calling (515) 294-5899.  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.

Crop Minute for Week Begining May 3

This growing season the ISU Extension crops team introduces the Crop Minute, a weekly audio crop update. Bob Hartzler, ISU Extension weed scientist encourages timely application of herbicide during this week’s crop minute, telling listeners that moderate to high infestation of weeds can begin to impact crop yield within a couple weeks of emergence.

mp3 - May 3 Crop Minute

Assess Seedling Health When Doing Stand Counts

By Alison Robertson, Department of Plant Pathology

Corn planting is virtually done, and across Iowa small green spikes are becoming visible as seed germinates. Now is the time to start assessing stands. Doing stand counts involves more than just counting the number of seedlings that have emerged. Seedling health should also be assessed. ISU Extension field agronomists Virgil Schmitt and Mark Carlton have reported that seedling rots are prevalent in southeast Iowa. 

Rotted seedlings may result from fungal infections, anhydrous ammonia injury, wireworms and cold injury. Seedling susceptibility to fungal infection increases the longer the seed sits in the ground, and the more stress germinating corn undergoes. Wet and cool (less than 55 F) soil conditions predispose seedlings to infection by a number of fungi.

Corn germinates well at soil temperatures above 68 F. When soil temperatures are below 55 F, germination is greatly retarded. This growing season, soil temperatures across much of the state were above 55 F from April 13 through April 23, when temperatures dropped below 55 F for two (central and northwest Iowa) to five (southeast Iowa) days (Figure 1). 

Last year, Gary Munkvold and I reviewed seedling diseases of corn and discussed some of the seed treatments that are available for corn in the ICM News article, Check General Root and Mesocotyl Health when Assessing Corn Stands. I encourage you to read through the article again. 

As you evaluate corn stands, remember to dig up seedlings and check for symptoms of seed rots and seedling blights. This will also give you an opportunity to evaluate the effectiveness of the seed treatment that was applied to the seed planted. If you have significant seedling rot, you may have to replant. For replant decisions, please see Roger Elmore and Lori Abendroth’s article on assessing corn stands for replanting.


soil temps

Figure 1. Mean 4-inch soil temperatures at ISU research farms from April 10 through April 30, 2010. Soil temperatures below 55 F greatly retard germination of corn and predispose seedlings to infection by a number of fungi.


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

Protect Your Corn Yields from Weeds

by Bob Hartzler, Department of Agronomy

Low glyphosate prices, a record pace of corn planting and high winds or rain have resulted in a high percentage of corn fields not being treated with preemergence herbicide programs. While weeds can be successfully controlled with a total postemergence program, early removal of weeds is essential in order to protect yield potential of the crop.

Weeds impact crop growth and yield primarily by competing with the crop for limited resources (e.g. light, nutrients, water). Early in the season a plant’s demand for these resources is small, therefore minimizing competition between the crop and weed.  However, recent research has documented that non-competitive interactions between weeds and corn very early in the season can significantly affect corn growth, development and yield potential, prior to the onset of significant competition for resources.

The cause of the non-competitive impact of weeds on corn growth is known as a shade avoidance response. Plants are able to detect the presence of neighboring plants due to changes in light quality (wavelength) when sunlight is reflected off nearby plant leaves. When a corn plant detects weeds in its vicinity, it reallocates resources to grow taller to reduce the chance of the weed intercepting sunlight the corn would use. While this response may reduce shading of the corn, it ultimately has a negative effect on future growth and development of the crop. Research in Canada found that corn growing in the presence of weeds was affected by the shade avoidance response as early as three days after emergence. Corn was most sensitive to shade avoidance in the first week after emergence.

The risk of reduced corn yields by the presence of weeds in the first week or two after emergence is affected by many factors that we do not fully understand. The best way to manage this risk is the use of preemergence herbicides to minimize weeds that emerge with the crop. When preemergence herbicides are not applied to a field, early post applications should be made as soon after corn emergence as possible if significant weed populations are present. Several preemergence herbicides can be applied with the post product to protect the crop from weeds that germinate after the application.

Alfalfa Weevil Scouting in 2010

By Adam Sisson, Corn and Soybean Initiative and Erin Hodgson, Department of Entomology

NOTE: This article was retracted on May 4, 2010 - due to new information and data. See the correction article.

Now is the time to scout for alfalfa weevil larvae in most crop reporting districts in Iowa. The scouting threshold has not yet been reached for northern and west central districts of the state but scouting dates are coming up quickly.

Growers in the southern three districts should start scouting for larvae at 200 growing degree days (using a base of 48 F), while those in the central and northern regions should start scouting at 250 growing degree days. This means that growers should presently be scouting fields in southern and most of the central districts of the state. Scouting for larvae should begin May 4 in the west central district and May 7 for all three northern districts of Iowa (Figure 1).
alfalfa weevil scouting date map

Figure 1. Alfalfa weevil scouting dates and accumulated growing degree days (using a base of 48 F) in Iowa from Jan. 1 to May 2, 2010.

Scouting, identification and economic thresholds for treatment of the alfalfa weevil are explained by Marlin E. Rice in a past ICM Newsletter article.



Adam Sisson is a program assistant with responsibilities with the Corn and Soybean Initiative. Sisson can be contacted by email at or by calling (515) 294-5899.  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.

Do CRP Acres Converted to Soybean Require Inoculation?

By Bob Hartzler, Department of Agronomy

Nitrogen fixation is the process of converting atmospheric nitrogen into a usable form for the plant and is critical for producing higher yields in soybean. For nitrogen-fixation to occur, the nitrogen-fixing bacteria known as Bradyrhizobia japonicum need to be readily available in the soil or must be applied to the seed to form nodules on the soybean root.  Because of the widespread production of soybean across Iowa, most Iowa fields have sufficient infestations of these bacteria to fully nodulate soybean without the use of supplemental inoculants. However, questions frequently arise concerning the need for seed inoculation when planting soybean in fields without a recent history of soybean production, such as fields in the Conservation Reserve Program (CRP).
Numerous inoculant experiments were conducted across Iowa by Iowa State University during the past five years. This research indicates no need to inoculate soybean if nodulated soybean have been grown in the field during the past 3 to 5 years and if soil pH has been maintained above 6.0. Soybean can benefit from inoculation in fields where soybean has not been grown recently, as with CRP acres, if fields have sandy soils and are irrigated, or if the field is flooded frequently. This recommendation is very similar to other states in the Midwest
For the typical soybean grower in Iowa with a corn-soybean rotation or a corn-corn soybean rotation we rarely see an advantage (or disadvantage) of using an inoculant. The major reason is the high frequency of soybean in crop rotations and the widespread soybean production, both of which keep the inoculant level adequate in most fields due to soybean presence and dust movement. In addition, Iowa soils are fertile and have a significant supply of plant available N that decreases the chance for severe N shortage in Iowa. However, it is recommended that if you put CRP ground into production in 2010, it would be a wise investment to inoculate your seed just to be sure that you do not have a shortage of N. More information about inoculants can be found on


Adapted from an article originally written by Palle Pedersen in 2008. Bob Hartzler is a professor of agronomy with extension, teaching and research responsibilities.

This article was published originally on 5/10/2010 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.