Skip Navigation

2/20/2012 - 2/26/2012

Precision Ag Technology Savings

By Matt Darr, Department of Agricultural and Biosystems Engineering

The use of precision farming products continues to increase. With increasing input costs, producers are often looking for ways to adopt technology to make farming operations more efficient and productive. Two precision ag products, auto guidance and automatic section control, lead the way in cost savings while also enhancing the productivity of machinery operations.

Guidance systems reduce overlap in fields which leads to less passes across the field, less fuel and product use (i.e. seed, fertilizer, and herbicide), and fewer operator hours. These savings can be directly calculated if the amount of overlap is known. Additionally, swath control products reduce seed and chemical overlap into headlands and field boundaries by automatically shutting off planter or boom sections as they cross into headland areas.

Measuring Production Overlap
To quantify the amount of overlap that occurs in a typical production setting Iowa State University researchers partnered with two Iowa producers in 2011 who did not own any precision ag technologies. Researchers instrumented the planter and spring tillage tools of each producer with high accuracy RTK GPS systems to record the amount of actual overlap that occurred during planting and tillage operations. More than 2,500 acres of field operations were monitored and analyzed to determine typical overlap in central Iowa production systems.

The planters used in this study included both a 16 and 24 row unit. Spring tillage was conducted with a 45 foot field cultivator. Results from these producer tests showed an average 3.3 percent overlap during planting operations. This overlap was due in part to planting point rows, but also had a significant component of overlap into perpendicular headlands. This is associated with a delayed response of the driver to lift the planter out of the ground when entering the headland. For spring tillage, a 7 percent overlap was measured and was mainly associated with pass-to-pass overlap of the outside section of the tillage tool into the previous field pass.

Calculating Return on Investment of Precision Ag Products
Given these overlap levels, the return on investment of autosteering and swath control products can be directly measured. For swath control both the cost of seed production and the loss of yield in double planted headland areas must be considered. Typical cost for corn seed in central Iowa is $113.80 per acre (Estimated Costs of Crop Production in Iowa – 2012, Duffy). A conservative estimate for yield loss in double planted areas is 12 percent based on previous research at Iowa State. For 175 bu/ac average corn yield with a value of $6/bu this results in a production loss of $7.91/ac. Based on this analysis the value of precision ag swath control systems in typical Iowa corn production is $7.91/ac.

Tillage saving when using a lightbar or autosteer system can be calculated in a similar manner. A 7 percent reduction in tillage overlap will result in approximately $1/ac cost savings. The cost savings is less due to a lack of high cost inputs, but still justifies lightbar systems even on the most basic tillage operations.


Illustration of automatic section control on a planter to reduce overlap and skipped areas.
(Fulton, J, D Mullenix, A Brooke, A. Winstead and B. Ortiz. "Automatic Section Control (ASC) Technology from Planters." Alabama Cooperative Extension System, Sept. 2011.)


Matt Darr is an assistant professor in Agricultural and Biosystems Engineering with research responsibilities on the use of embedded systems and advanced instrumentation in crop production. He can be reached at 515-294-8545 or Agricultural and Biosystems Engineering students contributing to the research were Chris Murphy, Clint Luellen, Cody Van Drie, and Eric Mensen.

Important Crop Insurance Dates

By William Edwards, Department of Economics

Even the best crop insurance plan is of little use if the right information is not collected and submitted on time. Likewise, if certain actions are not completed by the necessary date, producers may not receive full benefit from the risk protection that they have selected.

The table below shows important dates that need to be noted and observed. In some years the actual date may be the first business day after the listed date if the listed date falls on a weekend or holiday. Dates may vary for other crops and states. Farmers should make a list of the important dates that apply to their insured crops and mark their calendar. This will allow them to enjoy the full level of risk protection available to them.

Farmers should note two changes in deadline dates – acreage reporting date and billing date – highlighted in the chart below. For definitions and details related to the dates listed in the chart, see the publication Important Crop Insurance Dates, File A1-50.


Table. Important crop insurance dates for corn and soybeans in Iowa.


William Edwards is an Iowa State University professor of economics with extension responsibilities in farm business management. Edwards can be contacted at 515-294-6161 or by emailing

2011 Evaluation of Fungicide and Insecticide Seed Treatments on Soybean in Iowa

Alison Robertson, Daren Mueller, Stith Wiggs, Department of Plant Pathology and Microbiology; Erin Hodgson, Department of Entomology

The use of seed treatments on soybeans has increased considerably over the past few years. Seed treatments protect seed from seedling diseases, caused by Pythium, Phytophthora, Fusarium and Rhizoctonia, and also insect pests such as the bean leaf beetle. Although a seed treatment may help ensure uniform emergence and optimum stands, such benefits do not always result in greater yields. 

In Iowa, the benefits of a seed treatment on soybean have not been well studied. A 2011 field study, funded with check off dollars from the Iowa Soybean Association, evaluated the effect of commercially available fungicide and insecticide seed treatments on seedling disease, insect pests and soybean yield. The study was done at three locations in Iowa: ISU Northeast Research and Demonstration Farm (NERF) at Nashua, ISU Southeast Research and Demonstration Farm (SERF) near Crawfordsville, and a farmer’s field in Nevada (two planting dates). Twelve demonstration plots were also planted at the ISU Field Extension and Education Laboratory (FEEL) near Boone.

Materials and Methods
The experimental design at each location was a randomized complete block with four replications. Plot sizes were 10 feet wide (four rows) by 17.5 feet. Details on variety and planting and harvest dates are listed in Table 1. Unfortunately rain delayed our proposed planting dates by two weeks. Seed treatment products that were evaluated are listed in Table 2. 

In addition, the effect of a seed treatment plus a foliar application of Headline® (6 oz/A) + Leverage® (3.8 oz/A) applied at growth stage R3 on yield was compared with a seed treatment alone. Seedling disease and insect damage were assessed at 14 days after planting (dap) and 28 dap. One-meter stand counts was taken 14 and 28 dap, and vigor (plant height) was assessed 28 dap. Foliar and stem disease was assessed at growth stage R5. Soybean aphid populations were assessed at growth stage R1 and R3 to R4.5. Plots were harvested with a plot combine. Grain moisture at harvest was determined and yields were converted to bu/acre at 13 percent moisture.

Table 1. Variety, planting date, and harvest date for soybean seed treatment trials done at three locations in Iowa in 2011

Table 2. Seed treatment products tested in soybean seed treatment trials at three locations in Iowa and mean yield (bu/A) of each treatment


Field Study Results

Seedling disease and insect pests 
No seedling disease or insect damage occurred at any location.

Stand counts
There were no differences in stand counts at either 14 dap or 28 dap in three of the four trials. At Nevada 1, stand counts at 14 dap for the CruiserMaxx and CrusierMaxx Plus treatments were statistically greater than the control (untreated seed). At 28 dap, stand counts for the Trilex 6000 +Heads up treatment were statistically greater than the control. 

At Crawfordsville, soybean seedlings from seed treated with CruiserMaxx were more vigorous (taller) (P<0.1) than untreated control. At the early planting date at Nevada, seedling vigor of the AgriGardian Micro Mix and Foliar blend treatment was lower than the untreated control (P<0.1). For all other treatments, seedling vigor did not differ. There was no evidence of an effect of seed treatment on seedling vigor at Nashua or the later planting date at Nevada.

Foliar and stem disease
Weather conditions during grain fill were not favorable for foliar disease development. At Nashua, there was some Cercospora leaf blight, and an application of Headline+Leverage at R3, reduced disease severity (P<0.0001). Sudden death syndrome occurred in the trial at Crawfordsville but at very low incidence and no treatment effects were evident.

Soybean aphid
Soybean aphids were not present at all locations at R1, while at Nevada and Crawfordsville populations were extremely low (<10 aphids per plant) later in the growing season. At Nashua, the mean number of aphids per plant at growth stage R4.5 ranged from 41 to 63 in the treatments, well below threshold levels.

Yield varied across locations ranging from 51.1 to 63.3 bu/ac in the untreated control (Table 1). There was evidence of an affect of seed treatment on yield at all locations (P<0.1). At Crawfordsville, the yield of soybean treated with CruiserMaxx was greater than the untreated control (71.6 bu/A versus 63.3 bu/A). In the early planting date trial at Nevada, the CruiserMaxx (58.1 bu/A),CruiserMaxx Plus (58.1 bu/A), “Pioneer premium” (56.8 bu/A) and AgriGardian (56.5 bu/A) foliar blend treatments all yielded higher than the untreated control (51.3 bu/A). Yield of soybean treated with Trilex 6000 plus HeadUp was greater than that of the untreated control in the later planting date trial at Nevada (54.5 bu/A versus 51.1 bu/A). Lastly, at Nashua, the Trilex 6000 plus HeadUp (64.3 bu/A) and “Pioneer Premium” (64.3 bu/A) treatments yielded higher than the untreated control (57.9 bu/A).


In our 2011 field trials, the benefit of a seed treatment on soybean stand establishment was not evident, and yield varied among product and locations. We did however, plant into good seedbed conditions.

At the ISU Field Extension and Education Laboratory (FEEL) near Boone, we planted twelve demonstration plots on April 15, just as two weeks of very wet, cold weather conditions started. Six of the plots were inoculated with Pythium spp., and six with the SDS pathogen, Fusarium virgiliforme. Untreated seed was planted in one plot inoculated with each pathogen; the remaining five plots inoculated with each pathogen were each planted with soybean seed treated with a commercial seed treatment. Stand count was assessed 21 dap and 28 dap. At 21 dap, three seedlings had emerged across the 12 plots; at 28 dap, 41 percent of the non-treated seeds had emerged in each plot compared to 78 to 84 percent of the treated seeds in the remaining 10 plots (Figure 1). The benefits of seed treatments on soybeans have been well documented when planting conditions are not optimum, specifically if conditions at planting or soon after planting are cold and wet, and the plots at FEEL clearly bore this out.

Figure 1. Soybean stand counts of untreated and treated seed at 28 days after planting in demonstration plots inoculated with Pythium ssp., and Fusarium virgiliforme.
Plots were located at the ISU Field Extension and Education Laboratory near Boone, IA.


Funding for this study was provided by Iowa Soybean Association. Bayer CropScience, Syngenta and Valent treated seed for the study. Insect data was collected by Rebekah Ritson.


Alison Robertson is an associate professor in the plant pathology and microbiology department with extension and research responsibilities; contact her at or phone 515-294-6708.Daren Mueller is an extension specialist with responsibilities in the Iowa State University Integrated Pest Management program; contact at 515- 460-8000 or by email at Stith Wiggs is a research associate in plant pathology and micorbiology; contact at 515-294-1741 or Erin Hodgson is an assistant professor of entomology with extension and research responsibilities; contact at or phone 515-294-2847.

There’s Still Time to Check Fields for SCN Before 2012 Crop

By Greg Tylka, Department of Plant Pathology and Micobiology

Although the soybean cyst nematode (SCN) is one of the most persistent and destructive pests of soybean in Iowa and the Midwest, the potential to underestimate the nematode’s yield-reducing effects is great because damage from SCN is not readily apparent in the field during growing seasons with adequate to excess moisture. The need to take the threat of SCN seriously was recently reviewed in an ICM News article.

Fortunately, fields can be checked for the presence of SCN in the spring through soil sampling.


Guidelines for checking fields for SCN this spring

  • Soil cores should be collected from the upper eight inches of soil.
  • Do not collect samples if the fields are frozen or wet and muddy.
  • The more soil cores collected and the smaller the area sampled, the more accurate the results will be.
  • If corn or some other nonhost crop was last grown in the field, it doesn’t matter if soil cores are collected in the previous crop row, and it is better to collect soil cores after the previous nonhost crop rows have been destroyed by tillage.
  • If soybeans were last grown in the field, collect soil cores from under the old crop rows.
  • If sampling conventionally (not grid sampling), collect 15 to 20 soil cores in a zigzag pattern from no more than 20 acres. The 20-acre parcels of the field do not need to be square or rectangular; samples can be collected from zones according to the agronomic features of the field (figure 1).
  • If grid sampling: collect one or two extra soil cores from every grid cell sample and combine these extra cores from the number of cells that represent approximately 20 acres.
  • In fields where SCN has not been discovered, high-risk areas where SCN may be first found include high pH spots, low spots, near fence lines and other places where soil from other fields may have been introduced (figure 2).


Getting soil samples tested for SCN

Many private soil laboratories in Iowa and throughout the Midwest can process soil samples to determine SCN egg population densities. 
Also, samples can be sent to the Iowa State University for testing.  Mail samples to: 

Plant and Insect Diagnostic Clinic
327 Bessey Hall
Department of Plant Pathology and Microbiology
Iowa State University
Ames, IA 50011-1020

The current fee for SCN analysis at the ISU clinic is $15 per sample for samples from Iowa. Call the ISU Clinic at 515-294-0581 to check about processing of soil samples from outside Iowa. Samples sent to the clinic should be accompanied by a completed Plant Nematode Sample Submission Form

More information about SCN
Additional information about the biology, scouting and management of SCN, including many resources relating to SCN-resistant soybean varieties, can be found at and the Plant Health Initiative’s website

Figure 1. Sampling areas can be designated according to agronomic features of the field.

Figure 2. Areas of a field where soybean cyst nematodes are more likely to be found for the first time.


Greg Tylka is a professor with extension and research responsibilities in management of plant-parasitic nematode in the Department of Plant Pathology and Microbiology at Iowa State University. He can be reached at or 515-294-3021.

Review and Quiz Modules for Iowa Commercial Pesticide Applicator Manual Now Available

Betsy Buffington, Department of Entomology

A new CD/DVD, the Iowa Core Companion, now is available to assist those preparing for the commercial pesticide applicator core exam. It provides reviews and quizzes for a better understanding of the material covered in the Iowa Core Manual. The Iowa Core Companion review and practice quizzes are based on information needed to pass the Iowa Core examination for commercial pesticide applicators.

The review module, contains the learning objectives from each chapter of the core manual, case studies and over 100 review questions. The quiz module contains over 100 multiple-choice, true/false, and matching questions. This training should be used in association with the Iowa Core Manual, IC 445.

The Iowa Core Companion can be purchased as a set with the Iowa Core Manual or alone from the ISU Extension Online Store, 515-294-5247.  It also is available for digital download for the online store.


Betsy Buffington is a program specialist in the Pest Management and the Environment program. She can be reached at 515-294-7293 or

2012 Season is Not a Good One to “Roll the Dice” with SCN

By Greg Tylka, Department of Plant Pathology and Microbiology

The soybean cyst nematode (SCN) is one of Iowa’s most serious and persistent soybean pests. The nematode has the potential to cause devastating yield losses, population densities can increase very rapidly within a single growing season, and dormant eggs can survive for more than a decade in infested soils in the absence of soybeans. Random surveys funded by the soybean checkoff in 1995-1996 and again in 2006-2007 revealed that 70 to 75 percent of fields in Iowa are infested with the nematode.

SCN in dry years

The amount of symptoms and yield loss caused by SCN is affected greatly by the availability of moisture during the growing season. Symptoms and yield losses from SCN can be quite severe in dry years (figure 1). But symptoms can be mild (figure 2) or nonexistent and yield loss unnoticed in years with adequate or excess rainfall. Regardless of the extent of symptoms, SCN will produce three or more generations during a single growing season on susceptible soybeans, resulting in an increase in SCN egg population densities in the soil.

Hatched SCN juveniles enter soybean roots and form permanent feeding sites, called syncytia, inside the root tissue (figure 3). The SCN juveniles seem to establish feeding sites deeper into the root vascular tissue under dry soil conditions than wet conditions. Nematode feeding sites would be considerably more disruptive to root function if located in the vascular tissue than if in the outer cortex region of the roots. Also, SCN juveniles feeding in the vascular tissue could have better nutrition than those feeding in the root cortex, possibly leading to greater SCN reproduction, which somewhat supports the observation that SCN reproduction is greater under dry soil conditions.

Figure 1. Aerial image of severe SCN damage to soybeans in central Iowa in a dry growing season.

Dry soil can spell disaster if SCN is unmanaged

It has been 20 years or more since there has been widespread and severe damage from SCN in Iowa. And because of this, some people may have let down their guard on SCN. It is not uncommon for farmers to grow high-yielding, SCN-susceptible soybean varieties in fields with low or moderate SCN infestations.

As we approach spring planting season, increased vigilance about SCN is warranted for the 2012 growing season because of the dry soil conditions statewide. SCN can cause substantial yield loss to susceptible soybean varieties under dry soil conditions, even when SCN egg population densities are low. If soybeans will be produced in 2012 in fields infested with SCN, high-yielding SCN-resistant varieties should be grown.

Resistant soybeans: the foundation of SCN management - but all are not created equal

There are hundreds of SCN-resistant soybean varieties from which Iowa farmers can choose. Their availability was most recently reviewed in an October 2011 ICM News article.

The yield and nematode control provided by SCN-resistant soybean varieties can vary greatly because several genes confer SCN resistance and not every resistant variety possesses the full complement of resistance genes. The Iowa State University SCN-resistant Soybean Variety Trial Program annually assesses the agronomic performance and nematode control provided by hundreds of SCN-resistant soybean varieties. The work is supported by soybean checkoff funds from the Iowa Soybean Association. The results of the 2011 variety trial experiments were distributed in ISU Extension publication IPM 52, “Evaluation of Soybean Varieties Resistant to Soybean Cyst Nematode in Iowa - 2011," in the Jan. 21, 2012 issue of the Iowa Farmer Today magazine. The publication also can be downloaded from the ISU Extension's online store and the Iowa Soybean Association's production research library.

More information about SCN

Results from all variety trial locations from 1997 through 2011 can be found online at Also, more information about the biology and management of SCN can be found at and the Plant Health Initiative’s website.

Figure 2. Uneven plant height as a result of SCN damage in central Iowa in a wet growing season.


Figure 3. Stained soybean root segment with swollen SCN juvenile attached to feeding site inside the vascular tissue.


Greg Tylka is a professor with extension and research responsibilities in management of plant-parasitic nematode in the Department of Plant Pathology and Microbiology at Iowa State University.

This article was published originally on 2/27/2012 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.