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Soybean Cyst Nematode Reproduction High In 2012, Gregory L. Tylka Dec 2012

Soybean Cyst Nematode Reproduction High In 2012, Gregory L. Tylka

Integrated Crop Management News

The amount of damage caused by the soybean cyst nematode (SCN) is determined, in large part, by the population densities or numbers of the nematode present in the field. More severe yield losses generally occur in fields with high SCN population densities compared to damage in fields with low or moderate numbers of SCN. Long-term, profitable soybean production in fields infested with SCN requires growing SCN-resistant soybeans and nonhost crops, such as corn, to keep nematode population densities in check.


Managing Rotten Corn: An Overview Of Corn Ear Rots, Kiersten Wise Nov 2012

Managing Rotten Corn: An Overview Of Corn Ear Rots, Kiersten Wise

Proceedings of the Integrated Crop Management Conference

Ear rots of corn can reduce yield and grain quality. Several economically important ear rots impact the Corn Belt, including Diplodia ear rot, Gibberella ear rot, Fusarium ear rot, and Aspergillus ear rot. A different fungus causes each of these rots, and the environmental conditions at and just after silking influence which ear rot may be problematic in a given year. Additionally, some of these fungi are able to produce mycotoxins as a byproduct of the infection process. Mycotoxins can be toxic to humans and livestock, and are carefully regulated in food and feed. Proper identification of ear rots is ...


Research Update On Seedling Diseases Of Corn And Soybean Caused By Oomycete Pathogens, Alison Robertson, Azeem Ahmad, Rashelle Matthiesen-Andersen, James Peitzman, Erika Salaau-Rojas, Stith Wiggs, Martin Chilvers, Janette Jacobs, Alejandro Rojas Nov 2012

Research Update On Seedling Diseases Of Corn And Soybean Caused By Oomycete Pathogens, Alison Robertson, Azeem Ahmad, Rashelle Matthiesen-Andersen, James Peitzman, Erika Salaau-Rojas, Stith Wiggs, Martin Chilvers, Janette Jacobs, Alejandro Rojas

Proceedings of the Integrated Crop Management Conference

Uniform emergence and development of corn and soybean seedlings is key to maximize farmer profitability. In corn, poor stand and plant-to-plant variability lower yield potential as smaller plants compete with their larger neighbors for resources. With the dramatic increase in soybean seed costs within the past decade, farmers now plant fewer seeds per acre and thus depend on improved emergence and better stand establishment to achieve an even stand and maximize yield potential.


Crop Diversification: Impact On Weeds, Soybean Sudden Death Syndrome And Crop Productivity, Leonor Leandro, Matt Liebman, Craig Chase Nov 2012

Crop Diversification: Impact On Weeds, Soybean Sudden Death Syndrome And Crop Productivity, Leonor Leandro, Matt Liebman, Craig Chase

Proceedings of the Integrated Crop Management Conference

Crop diversification has diminished in the USA during the past 50 years, and monocultures and short rotation sequences are currently the prevalent cropping systems (Brummer, 1998; Cook, 2006). Simplification of cropping systems has been accompanied by greater reliance on synthetic pesticides and fertilizers to manage weeds, diseases and soil fertility, creating concerns about contamination of underground and surface water by nitrogen, herbicides and soil sediment (Hartwig and Ammon, 2002). Learning how to reduce reliance on synthetic fertilizers and pesticides without compromising farm productivity and profitability is a key priority for Iowa and other parts of the U.S. Corn Belt ...


The Impact Of The Drought On Grain Quality And Grain Processing, Charles R. Hurburgh Jr., Alison Robertson Nov 2012

The Impact Of The Drought On Grain Quality And Grain Processing, Charles R. Hurburgh Jr., Alison Robertson

Proceedings of the Integrated Crop Management Conference

The drought conditions sharply cut the quantity of corn at a time when demand was increasing at a rapid pace. Drought also creates grain quality issues such as the threat of aflatoxin, low test weight, loss of soybean protein and oil, and other problems. Current data shows that some predictions were right and while others were not. The emergence of food safety as a major focus of all food/feed industries presented some new challenges as well, because aflatoxin is classified as an Adulterant by the US Food and Drug Administration (FDA).


Probability Of Return On Investment With Using Soybean Seed Treatments, Paul Esker, Shawn Conley Nov 2012

Probability Of Return On Investment With Using Soybean Seed Treatments, Paul Esker, Shawn Conley

Proceedings of the Integrated Crop Management Conference

With soybean commodity prices at record high prices, the number of questions regarding key management considerations also remains high. One of the question that we often receive regards the use of seed treatments, in particular the use of seed treatment fungicides and/or insecticides. Since 2008, we have conducted trials throughout Wisconsin to examine if seed treatments are economically viable for soybean production. In particular, we are most interested in trying to answer the following question: “what is the probability that if I use a seed treatment, the cost of the application is covered?”


Corn And Soybean Diseases 2012: A Drought Year In Review, Daren S. Mueller, Alison Robertson Nov 2012

Corn And Soybean Diseases 2012: A Drought Year In Review, Daren S. Mueller, Alison Robertson

Proceedings of the Integrated Crop Management Conference

Disease development is dependent on three factors: the presence of a suitable host, a source of disease-causing inoculum, and favorable weather conditions so that the disease can develop. Together, these factors are called the plant-disease triangle, and all three “corners” of the triangle are required for disease to become a problem in corn and soybean. If any of the factors are missing or inadequate, disease has trouble becoming established. As anyone who raised crops in 2012 was aware, there was a definite shortage of water for many parts of Iowa and elsewhere, coupled with very hot weather. This weather produced ...


New Information And Videos On Website, Gregory L. Tylka Nov 2012

New Information And Videos On Website, Gregory L. Tylka

Integrated Crop Management News

Iowa State University has created and maintains a suite of pest-related web sites related to Iowa soybean production.


Hundreds Of Scn-Resistant Soybean Varieties Available For 2013, Integrated Crop Management News, Iowa State University Oct 2012

Hundreds Of Scn-Resistant Soybean Varieties Available For 2013, Integrated Crop Management News, Iowa State University

Integrated Crop Management News

Profitable soybean yields can be produced in fields infested with the soybean cyst nematode (SCN) by growing SCN-resistant soybean varieties. SCN-resistant soybeans can keep SCN population densities from increasing and produce high yields.

Each year, Iowa State University compiles a list of SCN-resistant soybean varieties that are available to Iowa soybean farmers for the upcoming growing season. The list is published with support from the Iowa Soybean Association. The updated version of the publication, titled “Soybean cyst nematode-resistant soybean varieties for Iowa,” is now available for use in planning the 2013 soybean crop.


Integrated Crop Management Conference Set For November 28–29, Alison E. Robertson, Brent A. Pringnitz Oct 2012

Integrated Crop Management Conference Set For November 28–29, Alison E. Robertson, Brent A. Pringnitz

Integrated Crop Management News

The Iowa State University (ISU) Integrated Crop Management Conference will be held Nov. 28 and 29 on the ISU campus. Registration begins at 7:30 am on Nov. 28 in the Scheman Continuing Education Building, and the program concludes at 4:00 pm on Nov 29.


Fall Soil Sampling For Scn Can Pay Big Dividends In 2013, Gregory L. Tylka Oct 2012

Fall Soil Sampling For Scn Can Pay Big Dividends In 2013, Gregory L. Tylka

Integrated Crop Management News

Now that harvest of this year’s crops is nearly complete in Iowa, it’s time to begin planning for the next growing season. For soybeans, that means taking soil samples to determine SCN population densities. Fall is a perfect time to do this.


Second Edition Of Soybean Cyst Nematode Field Guide Available, Gregory L. Tylka Oct 2012

Second Edition Of Soybean Cyst Nematode Field Guide Available, Gregory L. Tylka

Integrated Crop Management News

The soybean cyst nematode (SCN) is a major yield-limiting pathogen of soybeans in Iowa. The nematode was particularly damaging in the 2012 growing season because of the drought conditions. Thorough knowledge of SCN biology is the foundation for successful long-term management of the pest.

The Soybean Cyst Nematode Field Guide was first published and distributed by Iowa State University and the Iowa Soybean Association in 2008. The durable, pocket-sized book contains information about the biology of the nematode, as well as scouting methods, management strategies, disease interactions and the HG type test. A revised, second edition of the Soybean Cyst ...


Iowa Ipm Notes—Prevention, Detection, And Control Of Bed Bugs In The Home, Laura C. H. Jesse Oct 2012

Iowa Ipm Notes—Prevention, Detection, And Control Of Bed Bugs In The Home, Laura C. H. Jesse

Agriculture and Environment Extension Publications

Bug bugs are embarrassing and annoying. This fact sheet answers common questions related to preventing, detecting and controlling bed bugs in the home.


Fate Of Atrazine In Switchgrass-Soil Column System., Vurtice C. Albright Iii, Ian J. Murphy, Jennifer A. Anderson, Joel R. Coats Sep 2012

Fate Of Atrazine In Switchgrass-Soil Column System., Vurtice C. Albright Iii, Ian J. Murphy, Jennifer A. Anderson, Joel R. Coats

Entomology Publications

Atrazine, a broad-leaf herbicide, has been used widely to control weeds in corn and other crops for several decades and its extensive used has led to widespread contamination of soils and water bodies. Phytoremediation with switchgrass and other native prairie grasses is one strategy that has been suggested to lessen the impact of atrazine in the environment. The goal of this study is to characterize: (1) the uptake of atrazine into above-ground switchgrass biomass; and (2) the degradation and transformation of atrazine over time. A fate study was performed using mature switchgrass columns treated with an artificially-created agricultural runoff containing ...


Aflatoxin Detected In Fields In Central And Southern Iowa, Alison E. Robertson, Charles R. Hurburgh Jr. Aug 2012

Aflatoxin Detected In Fields In Central And Southern Iowa, Alison E. Robertson, Charles R. Hurburgh Jr.

Integrated Crop Management News

Within the past two weeks, there have been several reports of aflatoxin detected in southern Iowa and also a few reports from central Iowa. Levels of aflatoxin have ranged from 8 ppb to almost 200 ppb. The FDA action level for aflatoxin in grain is 20 ppb.


Black Mold On Corn, Alison E. Robertson Aug 2012

Black Mold On Corn, Alison E. Robertson

Integrated Crop Management News

There have been several reports of a black mold covering the leaves and stalks of corn plants across the state. Walking in these fields turn a white shirt black quickly. Not surprisingly, combining this blackened corn is also very dirty.


Identifying The Cause Of Yellow Patches In Soybeans, Daren S. Mueller Aug 2012

Identifying The Cause Of Yellow Patches In Soybeans, Daren S. Mueller

Integrated Crop Management News

Over the past week, we have observed yellow patches developing in soybean fields across Iowa (Figure 1). There are several different causes, including spider mites and soybean cyst nematode. However, we will look at three additional problems that are causing these patches: sudden death syndrome, charcoal rot and top dieback.


Crop Quality Issues From The Drought Of 2012, Charles R. Hurburgh Jr., Alison E. Robertson, Connie L. Hardy Aug 2012

Crop Quality Issues From The Drought Of 2012, Charles R. Hurburgh Jr., Alison E. Robertson, Connie L. Hardy

Integrated Crop Management News

As we approach harvest, the impact of the drought on grain quality is becoming clearer. Corn in many areas to the west and east of Iowa reached maturity earlier. Most of Iowa's corn will be past black layer by Labor Day weekend. Soybeans have stopped and started with late rains, but expect pod count and seed size to be pretty well set by Labor Day as well. Regardless of crop and quality issue, please talk to your crop insurance company before harvest. Some quality issues are covered; others are not. Quality issues are resolved in crop insurance by deducting ...


Aspergillus Ear Rot And Aflatoxin Production, Alison E. Robertson Aug 2012

Aspergillus Ear Rot And Aflatoxin Production, Alison E. Robertson

Integrated Crop Management News

Not surprisingly, the hot dry conditions we have been experiencing across the Corn Belt have many farmers and the grain industry concerned about aflatoxin, a potent mycotoxin that is produced by the fungal pathogen, Aspergillus flavus, which causes Aspergillus ear rot.

This article will briefly summarize the biology of Aspergillus ear rot, aflatoxin production and management recommendations for the next few weeks of this growing season.


Quantitative Structure–Activity Relationships Of Monoterpenoid Binding Activities To The Housefly Gaba Receptor, Fan Tong, Joel R. Coats Aug 2012

Quantitative Structure–Activity Relationships Of Monoterpenoid Binding Activities To The Housefly Gaba Receptor, Fan Tong, Joel R. Coats

Entomology Publications

BACKGROUND: Monoterpenoids are a large group of plant secondary metabolites. Many of these naturally occurring compounds have shown good insecticidal potency on pest insects. Previous studies in this laboratory have indicated that some monoterpenoids have positive modulatory effects on insect GABA receptors. In this study, the key properties of monoterpenoids involved in monoterpenoid binding activity at the housefly GABA receptor were determined by developing quantitative structure-activity relationship (QSAR) models, and the relationship between the toxicities of these monoterpenoids and their GABA receptor binding activities was evaluated.

RESULTS: Two QSAR models were determined for nine monoterpenoids showing significant effects on [3 ...


Possible Breakdown Of Scn Resistance Topic Of New Webcast, Gregory L. Tylka Jul 2012

Possible Breakdown Of Scn Resistance Topic Of New Webcast, Gregory L. Tylka

Integrated Crop Management News

Iowa farmers produce soybeans profitably in fields infested with the soybean cyst nematode (SCN) by growing SCN-resistant soybean varieties that yield well and prevent large increases in SCN egg population densities. There are hundreds of SCN-resistant soybean varieties for Iowa. Almost all of the varieties contain SCN resistance genes from a single breeding line, called PI 88788.


Mid-Season Soybean Disease And Fungicide Update, Daren S. Mueller, Nathan R. Bestor Jul 2012

Mid-Season Soybean Disease And Fungicide Update, Daren S. Mueller, Nathan R. Bestor

Integrated Crop Management News

While the hot, dry weather across the Midwest has affected soybean production, it has also negatively affected soybean diseases. In general, there is very little disease across Iowa in soybean. There have been a few fields with Septoria brown spot and Cercospora leaf blight, but it has been a quiet year for soybean diseases.


Symptoms Of Scn Damage Apparent Early, Yield Loss Likely Great In 2012, Gregory L. Tylka Jul 2012

Symptoms Of Scn Damage Apparent Early, Yield Loss Likely Great In 2012, Gregory L. Tylka

Integrated Crop Management News

As if the direct effects of Iowa’s hot, dry growing season on crops were not damaging enough, the soybean cyst nematode (SCN) probably will be more damaging this year than in the past two decades due to the lingering drought conditions.


Southern Rust Found In Central Iowa, Alison E. Robertson, Erika Saalau Rojas Jul 2012

Southern Rust Found In Central Iowa, Alison E. Robertson, Erika Saalau Rojas

Integrated Crop Management News

Southern rust was reported in several fields in Butler and Grundy counties late last week. Leaf samples were received by the ISU Plant Disease and Insect Clinic, and confirmations were made. Because common rust is widespread in cornfields in Iowa, it is important for farmers and agronomists to correctly distinguish between these two rusts, especially if a fungicide decision is to be made.


Tips For Diagnosing Goss's Wilt And Leaf Blight, Alison E. Robertson Jun 2012

Tips For Diagnosing Goss's Wilt And Leaf Blight, Alison E. Robertson

Integrated Crop Management News

In the past 5 years, Goss’s wilt and leaf blight has become increasingly prevalent in Iowa. This growing season, the disease has already been reported from several fields. Consequently many agronomists and scouts have been checking fields and some agronomists have been making use of the immunostrip test from AgDia.


New Fungicide Questions Creeping Into The Conversation, Daren S. Mueller, Alison E. Robertson Jun 2012

New Fungicide Questions Creeping Into The Conversation, Daren S. Mueller, Alison E. Robertson

Integrated Crop Management News

Across Iowa many farmers and agronomists are starting to ask if or when to apply fungicide on corn and soybeans. Like the past few years, there have been very little early season foliar problems on both crops. In soybean, frogeye leaf spot, Cercospora leaf blight, and brown spot have been reported on seedlings. Brown spot is really the only foliar disease still being reported, although soybeans usually grow out of any early season infection. Likewise in corn, very few foliar diseases have been found prior to tasseling.


Should You Be Scouting For Goss's Wilt?, Alison E. Robertson Jun 2012

Should You Be Scouting For Goss's Wilt?, Alison E. Robertson

Integrated Crop Management News

This weekend, Dr Tamra Jackson-Ziems at University of Nebraska-Lincoln reported that Goss’s wilt had been spotted in multiple cornfields in three counties in south central and eastern Nebraska. She suspects that infection may have occurred as a result of plant wounding due to severe storms earlier in the growing season. The infected corn plants were at the V6 growth stage and had characteristic lesions of Goss’s wilt. A few plants were systemically infected.


New Approach To Assessing Possible Nematode Damage To Corn, Gregory L. Tylka Jun 2012

New Approach To Assessing Possible Nematode Damage To Corn, Gregory L. Tylka

Integrated Crop Management News

Many different species of plant-parasitic nematodes occur in cornfields throughout the Midwest. Most of these microscopic, parasitic worms must reach a damage threshold number before they cause yield loss in corn. The damage threshold numbers for most nematodes that feed on corn in Iowa (see Common Corn Nematode Characteristics, ICM News, Aug. 3, 2009) are 100 or more worms per 100 cm3 , which is a little less than a half-cup of soil. The exceptions are the needle and sting nematodes, which damage corn even if only one or two worms per 100 cm3 soil are present. Fortunately, needle ...


Now Is The Time To Look For Scn Females On Soybean Roots, Gregory L. Tylka Jun 2012

Now Is The Time To Look For Scn Females On Soybean Roots, Gregory L. Tylka

Integrated Crop Management News

The soybean cyst nematode (SCN) is one of the most serious soil-borne pathogens of soybean in Iowa and throughout the Midwest. Juveniles of this microscopic worm hatch from eggs in the spring, then burrow into soybean roots, where they attach to the vascular tissue of the plant and feed (Figure 1). Developing SCN females get progressively larger as they mature, until their fully expanded, lemon-shaped bodies rupture out of the root and become visible on the root surface.


Effects Of Entomopathogenic Nematodes On Evolution Of Pink Bollworm Resistance To Bacillus Thuringiensis Toxin Cry1ac, Aaron J. Gassmann, Eugene R. Hannon, Mark S. Sisterson, S. Patricia Stock, Yves Carriere, Bruce E. Tabashnik Jun 2012

Effects Of Entomopathogenic Nematodes On Evolution Of Pink Bollworm Resistance To Bacillus Thuringiensis Toxin Cry1ac, Aaron J. Gassmann, Eugene R. Hannon, Mark S. Sisterson, S. Patricia Stock, Yves Carriere, Bruce E. Tabashnik

Entomology Publications

The evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from Bacillus thuringiensis (Bt). However, fitness costs may act to delay pest resistance to Bt toxins. Meta-analysis of results from four previous studies revealed that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) imposed a 20% fitness cost for larvae of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), that were homozygous for resistance to Bt toxin Cry1Ac, but no significant fitness cost was detected for heterozygotes. We conducted greenhouse and laboratory selection experiments to determine whether S. riobrave would delay the evolution of pink ...