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Iowa State University

Plant Sciences

2011

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First Iowa Confirmation Of Resistance To Bt Corn By Western Corn Rootworm, Erin W. Hodgson, Aaron J. Gassmann Dec 2011

First Iowa Confirmation Of Resistance To Bt Corn By Western Corn Rootworm, Erin W. Hodgson, Aaron J. Gassmann

Integrated Crop Management News

Starting in 2009, the Department of Entomology at Iowa State University received reports of severe corn rootworm injury in Bt corn in Iowa. In all cases, western corn rootworm was the predominant rootworm species in these fields (Fig. 1).


Catnip Essential Oil And Its Nepetalactone Isomers As Repellents For Mosquitoes, Christopher J. Peterson, Joel R. Coats Dec 2011

Catnip Essential Oil And Its Nepetalactone Isomers As Repellents For Mosquitoes, Christopher J. Peterson, Joel R. Coats

Entomology Publications

The effect of catnip Nepeta cataria essential oil and two isomers of nepetalactone, the major components, on the distribution of Aedes aegypti (yellow fever mosquito) mosquitoes in a static-air olfactometer response was examined to determine their activity as spatial repellents. A glass cylinder was used as a choice-test chamber. The catnip (Nepeta cataria) essential oil, as well as the E,Z- and Z,E-isomers of nepetalactone were significantly repellent after application of one ml of 1% and 0.1% solution to filter paper (conc. of 157 and 15.7 µg/cm2). Diethyl-m-toluamide (DEET) a positive control was ...


Preface Of Recent Developments In Invertebrate Repellents, Gretchen E. Paluch, Joel R. Coats Dec 2011

Preface Of Recent Developments In Invertebrate Repellents, Gretchen E. Paluch, Joel R. Coats

Entomology Publications

As the global climate changes, scientists anticipate that the distribution of animal populations and disease vectors will expand. In the case of arthropods, such efforts hold immense significance as they have the potential to increase human mortality and suffering from arboviruses above current levels. The 238th American Chemical Society National Meeting and Exposition in Washington, D.C. on August 16-20, 2009, offered an opportunity for researchers to present and discuss new findings in invertebrate repellents research, regulations, and technology development.


Change In Phosphorus And Potassium Contents Of Cornstalks Over Time, Antonio P. Mallarino, Ryan R. Oltmans Dec 2011

Change In Phosphorus And Potassium Contents Of Cornstalks Over Time, Antonio P. Mallarino, Ryan R. Oltmans

Integrated Crop Management News

Increasing corn yield and harvest of cornstalks for feed, bedding or bioenergy production are generating numerous questions about phosphorus (P) and potassium (K) concentrations in cornstalks and removal. The functions of P and K in plants influence their accumulation in different plant parts, and also may influence the magnitude of losses from live tissue or residue. A larger proportion of the total plant P is in grain compared with K, and most of the absorbed P is incorporated into the plant organic matter but K is in the inorganic soluble ion form. Therefore, P and K amounts removed by cornstalk ...


Cca Exam Review Course Offered By Isu Extension, Brent A. Pringnitz Dec 2011

Cca Exam Review Course Offered By Isu Extension, Brent A. Pringnitz

Integrated Crop Management News

Individuals planning to take the Certified Crop Adviser (CCA) exam can attend a two-day Iowa State University (ISU) Extension and Outreach course to prepare for taking the certification exam. During the CCA Exam Review Course, ISU Extension specialists will cover the performance objectives for the exam and focus on areas where students may need additional assistance. Interactive quizzes and a final practice examination will be included in the course.


A 10-Year Summary Of Testing For Nematodes That Feed On Corn In Iowa, Gregory L. Tylka Dec 2011

A 10-Year Summary Of Testing For Nematodes That Feed On Corn In Iowa, Gregory L. Tylka

Integrated Crop Management News

The Iowa State University (ISU) Plant and Insect Diagnostic Clinic is the only facility in Iowa that extracts and identifies plant-parasitic nematodes from soil and root samples submitted by farmers and those who advise them. The results of testing for nematodes that feed on corn in Iowa from 2000 to 2010 were summarized and published in an article this week titled “Testing for Plant-parasitic Nematodes that Feed on Corn in Iowa 2000-2010,” by G.L. Tylka, A.J. Sisson, L.C. Jesse, J. Kennicker, and C.C. Marett in the online journal Plant Health Progress.

The main findings of the ...


Subsoil Moisture Levels A Concern For Northwest Iowa 2012 Crops, Paul C. Kassel Dec 2011

Subsoil Moisture Levels A Concern For Northwest Iowa 2012 Crops, Paul C. Kassel

Integrated Crop Management News

The northwest Iowa fall survey of subsoil moisture completed by Iowa State University in November shows well below average amount of subsoil moisture. Subsoil moisture levels are checked in the fall in many northwest Iowa counties through this survey.


New Stink Bug Identification Card Available, Laura Jess, Erin W. Hodgson Dec 2011

New Stink Bug Identification Card Available, Laura Jess, Erin W. Hodgson

Integrated Crop Management News

A new, pocket-sized identification card for stink bugs in the Midwest will make identification of these insects much handier. Iowa State University Extension has just released the new identification card from authors Laura Jesse, Erin Hodgson, Donald Lewis, Matt O’Neal and Adam Sisson. The card was made possible with funding from a 2011 North Central IPM Center mini-grant.


Weed Identification Guide Available Electronically, Daren S. Mueller Dec 2011

Weed Identification Guide Available Electronically, Daren S. Mueller

Integrated Crop Management News

The popular Weed Identification Field Guide is now available electronically as an e-book and, for the first time, downloadable on iPad. The publication is distributed by the Iowa Soybean Association (ISA) and Iowa State University (ISU) Extension and Outreach. Pioneer Hi-Bred, a DuPont business, has sponsored the capability for users to download the electronic versions for no charge.


2011 Iowa Crop Performance Tests For Corn And Soybean, Jim R. Rouse Dec 2011

2011 Iowa Crop Performance Tests For Corn And Soybean, Jim R. Rouse

Integrated Crop Management News

Final results of the 2011 Iowa Crop Performance Tests for corn and soybeans are now available online at the Iowa State University Crop Testing website and asdownloadable publications from the ISU Extension Online Store. All single-location and district data are available for online viewing and can also be downloaded as Excel files from the crop testing site.


Oomycete Diseases In The North-Central Region: A Survey Of Certified Crop Advisers, J. Gordon Arbuckle, Alison E. Robertson Dec 2011

Oomycete Diseases In The North-Central Region: A Survey Of Certified Crop Advisers, J. Gordon Arbuckle, Alison E. Robertson

Sociology Technical Reports

This report presents the results of a web-based survey of certified crop advisers conducted as part of the Integrated Management of Oomycete Diseases of Soybean and other Crop Plants Project funded by USDA-NIFA. The survey represents a first step in a project-long effort to engage members of the Certified Crop Adviser (CCA) program of the American Society of Agronomy in educational and extension activities focused on improving their ability to accurately diagnose and manage soybean seedling and root diseases, particularly those caused by oomycetes. The report consists of two sections. This first section describes the survey’s objectives and methods ...


Annual Warm-Season Grasses Vary For Forage Yield, Quality, And Competitiveness With Weeds, Andrew W. Lenssen, S. Dennis Cash Dec 2011

Annual Warm-Season Grasses Vary For Forage Yield, Quality, And Competitiveness With Weeds, Andrew W. Lenssen, S. Dennis Cash

Andrew W. Lenssen

Warm-season annual grasses may be suitable as forage crops in integrated weed management systems with reduced herbicide use. A 2-year field study was conducted to determine whether tillage system and nitrogen (N) fertilizer application method influenced crop and weed biomass, water use, water use efficiency (WUE), and forage quality of three warm-season grasses, and seed production by associated weeds. Tillage systems were zero tillage and conventional tillage with a field cultivator. The N fertilization methods were urea broadcast or banded near seed rows at planting. Warm-season grasses seeded were foxtail (Setaria italica L.) and proso (Panicum mileaceum L.) millets, and ...


Herbicide-Resistant Weeds: An Evolving Problem Of Importance In Iowa Crop Production, Micheal D. K. Owen Dec 2011

Herbicide-Resistant Weeds: An Evolving Problem Of Importance In Iowa Crop Production, Micheal D. K. Owen

Proceedings of the Integrated Crop Management Conference

The changes in Iowa agriculture over the last three decades have been monumental and the implications of these changes often overlooked during the course of developing the plans for next year.


Nitrate Loss In Subsurface Drainage As Affected By Nitrogen Application Rate And Timing Under A Cornsoybean Rotation System, Matthew J. Helmers, Reid D. Christianson, John Sawyer Dec 2011

Nitrate Loss In Subsurface Drainage As Affected By Nitrogen Application Rate And Timing Under A Cornsoybean Rotation System, Matthew J. Helmers, Reid D. Christianson, John Sawyer

Proceedings of the Integrated Crop Management Conference

Subsurface agricultural drainage has allowed for enhanced crop production in many areas of the world including the upper Midwest, United States. However, the presence of nitrate-nitrogen (nitrate-N) in subsurface tile drainage water is a topic of intense scrutiny due to several water quality issues. Many studies have been conducted looking at ways to reduce nitrate-N in tile drainage (Baker et al., 1975; Baker and Johnson, 1981; Hanway and Laflen, 1974; Kanwar et al., 1988).With the growing concern for the health of the Gulf of Mexico (Mitsch et al., 2001; Rabalais et al., 1996) and local water quality concerns, there ...


Herbicide Resistance In Waterhemp: Past, Present, And Future, Patrick J. Tranel Dec 2011

Herbicide Resistance In Waterhemp: Past, Present, And Future, Patrick J. Tranel

Proceedings of the Integrated Crop Management Conference

Over the last couple of decades, waterhemp has transitioned from being a relatively unknown weed species to one of the worst weeds in the Midwest (Steckel 2007). Its recent success as a weed can be attributed both to its biological characteristics and to changes in weed management practices (Costea et al. 2005).


Fertilizer Situation And Outlook, David Asbridge Dec 2011

Fertilizer Situation And Outlook, David Asbridge

Proceedings of the Integrated Crop Management Conference

No abstract provided.


Nutrient Uptake By Corn And Soybean, Removal, And Recycling With Crop Residue, Antonio P. Mallarino, Ryan R. Oltmans, Jacob R. Prater, Carlos X. Villavicencio, Louis B. Thompson Dec 2011

Nutrient Uptake By Corn And Soybean, Removal, And Recycling With Crop Residue, Antonio P. Mallarino, Ryan R. Oltmans, Jacob R. Prater, Carlos X. Villavicencio, Louis B. Thompson

Proceedings of the Integrated Crop Management Conference

The prevailing phosphorus (P) and potassium (K) management system in Iowa and the Midwest is based on soil testing, response-based fertilizer application for low-testing soils, and removal-based fertilizer application to maintain desirable soil-test P (STP) and soil-test K (STK) values. Several issues are important for an effective implementation of this management concept. These include use of appropriate soil-test methods and field calibrations to determine optimum soil-test levels and fertilization rates, knowledge of fertilization and cropping impacts on soil-test values over time, and reliable estimates of P and K removal with harvest. In Iowa, continued research during the last two decades ...


Assessing The Benefits Of Pyramids And Seed Treatments For Soybean Aphid Host Plant Resistance, Michael Mccarville, Matthew E. O'Neal, Walter R. Fehr Dec 2011

Assessing The Benefits Of Pyramids And Seed Treatments For Soybean Aphid Host Plant Resistance, Michael Mccarville, Matthew E. O'Neal, Walter R. Fehr

Proceedings of the Integrated Crop Management Conference

Soybean aphid resistant varieties were first released commercially in 2010. Currently all commercially available resistant varieties incorporate the Rag1 (Resistance to Aphis glycines) gene. Research from the past three years have shown: Across multiple states and years, Rag1 containing-soybeans have fewer aphids than aphid-susceptible soybeans; When aphids are present in a field, Rag1 containing-soybeans are never aphid free (Mardorf et al. 2010); Rag1 does not limit yield (Kim and Diers 2009, Mardorf et al. 2010); and Combining Rag1 and Rag2 in a soybean line provides more resistance than Rag1 or Rag2 alone (Wiarda et al. 2011).


Making Silage From Iowa's Forage Crops, Stephen K. Barnhart Dec 2011

Making Silage From Iowa's Forage Crops, Stephen K. Barnhart

Proceedings of the Integrated Crop Management Conference

Proper ensiling is a controlled fermentation, which converts perishable wet forage plant material to a stable, stored feed energy source. Good ensiling management is required for high silage quality and dry matter (DM) recovery. To guide silage management practices, it is important to understand the biological and chemical processes that occur during ensiling, their effects on silage quality, and how these processes can be managed to help produce a more consistent feedstuff.


Growin’ Good Corn: Rocket Science Or Common Sense?, R.L. (Bob) Nielsen Dec 2011

Growin’ Good Corn: Rocket Science Or Common Sense?, R.L. (Bob) Nielsen

Proceedings of the Integrated Crop Management Conference

For 70 years, beginning in 1866, national corn grain yields in the U.S. were essentially flat (Fig. 1) and averaged only 26 bpa (bushels per acre) during that entire 70-year time period. The absence of noticeable yield improvement throughout all those years is remarkable given that farmers of the day were essentially also plant breeders practicing a recognized form of plant breeding (mass selection) as they saved the best ears from each year’s crop for planting the next.


Weed Management For 2012, Micheal D. K. Owen Dec 2011

Weed Management For 2012, Micheal D. K. Owen

Proceedings of the Integrated Crop Management Conference

While there have not been many new things in weed control/management for 2012, some that have occurred are not necessarily good. Herbicide resistance, particularly in common waterhemp has escalated significantly for populations with evolved resistance to glyphosate and resistance to HPPD herbicides has predictably has been identified in a number of locations across Iowa. Unfortunately, again as predicted, no new “silver bullets” have surfaced and in fact, it is unlikely that new herbicide mechanisms of action will be introduced in the foreseeable future. Thus it comes that much more important to recognize the tactics that are available and establish ...


Goss’S Wilt: Get The Facts, Alison Robertson, Charlie Hurburgh, Lisa Shepherd, Charlie Block, Roger Elmore Dec 2011

Goss’S Wilt: Get The Facts, Alison Robertson, Charlie Hurburgh, Lisa Shepherd, Charlie Block, Roger Elmore

Proceedings of the Integrated Crop Management Conference

Goss’s wilt and leaf blight is caused by the bacterium Clavibacter michiganensis subsp. nebraskense (Cmn). Historically, this disease has been a concern only to growers in western Nebraska and eastern Colorado on irrigated fields. In 2008, Goss’s wilt was reported in eight counties in Iowa and its prevalence has increased each year. In 2011, the disease was widespread throughout the central and northern two thirds of Iowa. It was also reported in a few counties in the southern third tier of counties. Why the sudden increase in the prevalence of this disease? Has the pathogen changed? Are various ...


Midwest Crop Weather 2011-2012: What Follows A Strong La Niña?, Elwynn Taylor Dec 2011

Midwest Crop Weather 2011-2012: What Follows A Strong La Niña?, Elwynn Taylor

Proceedings of the Integrated Crop Management Conference

The abnormal 2011 weather for much of the Earth turned out very much as it had been during the previous La Niña events of like strength (1952-5/1974).


Corn And Soybean Response To Soil Ph Level And Liming, Antonio P. Mallarino, Agustin Pagani, John E. Sawyer Dec 2011

Corn And Soybean Response To Soil Ph Level And Liming, Antonio P. Mallarino, Agustin Pagani, John E. Sawyer

Proceedings of the Integrated Crop Management Conference

Limestone application to raise soil pH is needed when the pH is too acidic to allow for optimum crop growth and yield. Some Iowa soils are naturally acidic, and others become acidic over time mainly due to sustained N application for corn with urea or ammonium-based products that acidify soils during the microbial transformation of ammonium to nitrate (nitrification). Soil pH decreases as the acidity increases because the pH measurement expresses acidity as the negative logarithm of H+ ion concentration. Alfalfa is the most sensitive crop to low pH grown in Iowa, while forage grasses are the least sensitive and ...


Long Silks, Short Pollen… A Long Year?, Roger W. Elmore Dec 2011

Long Silks, Short Pollen… A Long Year?, Roger W. Elmore

Proceedings of the Integrated Crop Management Conference

Corn harvest is nearly complete in Iowa as I write this, 19 days ahead of the 5-year normal and slightly behind that of last year (USDA-NASS, 2011a). Many farmers already report corn and soybean yields are “better than expected.” Does that mean the crop is turning out better than they expected at planting, in early July, in early August?


A Reintroduction To Soil Applied Herbicides, Bob Hartzler Dec 2011

A Reintroduction To Soil Applied Herbicides, Bob Hartzler

Proceedings of the Integrated Crop Management Conference

Although the growth regulator herbicides (2,4-D; dicamba, etc.) were responsible for ushering in the chemical era of weed control in the late 1940’s, it was the introduction of the triazine, dinitroaniline and amide herbicides that transformed weed control in corn and soybean.


Residue Biomass Removal And Potential Impact On Production And Environmental Quality, Mahdi Al-Kaisi, Jose Guzman Dec 2011

Residue Biomass Removal And Potential Impact On Production And Environmental Quality, Mahdi Al-Kaisi, Jose Guzman

Proceedings of the Integrated Crop Management Conference

The implementation of conservation systems to sustain soil and improve environmental quality has to be considered in the current trend toward the increase of continuous corn acreage and future thinking of corn residue removal for cellulosic ethanol production. There is a high possibility that continuous corn production can increase the use of conventional tillage.


Diversified Weed Management Tactics In Diversified Cropping Systems: Foundations For Durable Crop Production And Protection, Matt Liebman Dec 2011

Diversified Weed Management Tactics In Diversified Cropping Systems: Foundations For Durable Crop Production And Protection, Matt Liebman

Proceedings of the Integrated Crop Management Conference

One of the key questions facing Iowa’s agricultural community is how to produce sufficient amounts of food and farm income while improving and protecting environmental quality. Because synthetic fertilizers and pesticides constitute important expenses in Iowa farming systems (Duffy 2011; National Agricultural Statistics Service 2011) and because their use can be linked to environmental damage (U.S. Geological Survey 1999; Dinnes et al. 2002; Gilliom et al. 2006), learning how to reduce reliance on these materials without compromising farm productivity and profitability is a key priority for Iowa and other parts of the U.S. Corn Belt.


Effect Of A Rye Cover Crop And Crop Residue Removal On Corn Nitrogen Fertilization, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker Dec 2011

Effect Of A Rye Cover Crop And Crop Residue Removal On Corn Nitrogen Fertilization, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker

Proceedings of the Integrated Crop Management Conference

Nitrogen (N) fertilizer applications are necessary for high yield corn production. However, water quality impairment related to N loss from corn and soybean fields continues to be a concern in Iowa, including meeting the USEPA nitrate (NO3-–N) drinking water standard, meeting proposed surface water quality nutrient criteria, and reducing N export to the Gulf of Mexico. Therefore, in-field production practices are needed to aid in reduction of NO3- leaching and movement to water systems.


Artificial Soils To Assess Temperature Sensitivity Of The Decomposition Of Model Organic Compounds: Effects Of Chemical Recalcitrance And Clay-Mineral Composition, James W. Raich, Jiaoping Zhang, Thomas E. Loynachan Dec 2011

Artificial Soils To Assess Temperature Sensitivity Of The Decomposition Of Model Organic Compounds: Effects Of Chemical Recalcitrance And Clay-Mineral Composition, James W. Raich, Jiaoping Zhang, Thomas E. Loynachan

Ecology, Evolution and Organismal Biology Publications

Understanding the temperature sensitivity of soil organic matter (SOM) decomposition is important to predict the response of soil carbon (C) dynamics to projected global warming. There is no consensus, however, as to whether or not the decomposition of recalcitrant soil C is as sensitive to temperature as is that of labile soil C. Soil C is stabilized by three mechanisms: chemical recalcitrance, mineral interaction and physical accessibility. We used artificial soils with controlled compositions to assess the effects of chemical recalcitrance (cellulose compared with lignin) and clay-mineral composition with montmorillonite (M) or kaolinite (K) on the decomposition of model organic ...