Crop Protection T echnology Conference
UNIVERSITY OF ILLINOIS extension Contents
i Lessons from a “ Quiet” 2006 Season—What Lies Ahead? Climate Patterns: Past, Present, and Future Jim Angel 5 Lessons from a “ Ouiet” 2006 Season—-What Lies Ahead? Crop Production Emerson D , Nafziger 7 Lessons from a “ Quiet” 2006 Season—What Lies Ahead? Weed Management Aaron G. Hager 10 Lessons from a “ Quiet” 2006 Season—What Lies Ahead? Rust Is Here; Now What? Suzanne Bissonnette 13 Lessons from a “ Quiet” 2006 Season—-What Lies Ahead? Nematode Management Terry L. Niblack 16 Lessons from a “ Quiet” 2006 Season—What Lies Ahead? Insect Management Kevin L, Stejfey and Michael E. Gray 21 Soybean Rust: The First Three Years Glen Hartman 26 Integration—-The Key to Managing Fusarium Head Blight (FHB = Scab) in Wheat Marcia McMullen 29 Fungicides on Hybrid Corn: Yield Impact of Foliar Disease Control Gary P. Munkvold 34 Application Strategies to Improve Crop Health Robert E . W olf
2007 Illinois Crop Protection Technology Conference ♦ lil 39 Tillage System Effects on Root Growth and Fertilizer Placement Considerations R.M . Cruse 41 Why Is My Field Showing Potassium Deficiency? Fabian G. Fernandez 45 The Perfect Corn Stand Emerson D. Nafziger 48 Fitting Wheat into Illinois Cropping Systems Emerson D. Nafziger 51 Wheat Disease Management Gregory Shaner 53 Development of Fusarium Head Blight-Resistant Wheat Varieties Frederic L. Kolb 57 Managing Insects in Wheat: An Overview Douglas W. Johnson 61 Glyphosate-Resistant Palmer Amaranth Impacts Southeastern Agriculture A. Stanley Culpepper and Alan C. York 64 Glyphosate-Resistant Waterhemp: Our Experiences in Missouri Kevin Bradley 68 Predicting the Evolution and Spread of Glyphosate-Resistant Waterhemp Patrick J. Tranel 70 Preparing for the Inevitable—A Prescription for Resistance Dawn Nordby 72 Soybean Aphid Management: What Works and What Doesn’t M att O'Neal, Kevin Johnson, and Nicholas Schmidt 78 Western Bean Cutworm and the Invasion of Illinois Corn: It’s Like Deja vu All Over Again Marlin E . Rice 84 Transgenic Corn Root worm Hybrids: Assessing Performance in a Variant Western Corn Rootworm Arena Michael E. Gray, Kevin L. Stejfey, Ronald E, Estes, and Jared B. Schroeder 93 Seed-Applied Insecticides, Soil Insecticides, and Bt Corn: Their Roles in Corn Production Kevin L. Stejfey, Michael E. Gray, Jared B. Schroeder, and Ronald E. Estes 99 Who’s Your Neighbor? Jack Erisman
IV ♦ 2007 Illinois Crop Protection Technology Conference ioo Managing the Risks of Custom Application: An Industry Perspective Jean Payne 103 Surviving on the Fence Between Emerald City and Oz Donald Meyer 107 A Regulatory Perspective on the Rural Agricultural Production/Urban Interface Gerald Kirbach 109 Identifying and Protecting Organic Farms from Contamination with Prohibited Substances Cissj Bowman 114 Is Extension Delivering Relevant and Effective Integrated Pest Management Corn and Soybean Programs? Wendy Wintersteen
2007 Illinois Crop Protection Technology Conference ♦ V Planning Committee
Co-Chairs: Aaron Hager Department of Crop Sciences Mike Gray University of Illinois at Urbana-Champaign Department of Crop Sciences University of Illinois at Urbana-Champaign Mike Hellmer Pioneer Hi-Bred International, Inc. Sandy Osterbur Department of Crop Sciences Gerald Kirbach University of Illinois at Urbana-Champaign Illinois Department of Agriculture Kevin StefFey Emerson Nafziger Department of Crop Sciences Department of Crop Sciences University of Illinois at Urbana-Champaign University of Illinois at Urbana-Champaign Dawn Nordby Committee Members: Department of Crop Sciences University of Illinois at Urbana-Champaign Steve Ayers Champaign Extension Unit Bruce Paulsrud University of Illinois Extension Department of Crop Sciences University of Illinois at Urbana-Champaign Suzanne Bissonnette Champaign Extension Center Jean Payne University of Illinois Extension Illinois Fertilizer and Chemical Association Kevin Black Rick Reed Growmark, Inc. Illinois Agricultural Aviation Association Scott Bretthauer John Reifsteck Department of Agricultural & Biological Engineering Champaign County Producer University of Illinois at Urbana-Champaign Kevin Runkle Fabian Fernandez Illinois Fertilizer and Chemical Association Department of Crop Sciences Dennis Thompson University of Illinois at Urbana-Champaign Illinois Crop Improvement Association Todd Gleason Information Technology 8C Communication Services University of Illinois at Urbana-Champaign
vi 2007 Illinois Crop Protection Technology Conference Illinois Crop Protection Wednesday Afternoon, January 3
Technology Conference Symposia A, B, and C run con ■ . from Program 1:00..2 :4 5 p m ■ ■ Symposium A ♦ Healthy Plantst Is Your Disease Threshold Wednesday Morning, January 3 Damaged? ♦ Illini Rooms A and B ♦ Opening Session ♦ Illini Rooms A, B, and C ♦ Suzanne Bissonnette and Bruce Paulsrud, Moderators Todd Gleason, Moderator (1.5 CCA credits in Integrated Pest Management) (1.5 CCA credits in Integrated Pest Management and 1.0 CCA The symposium will address current issues regarding disease credit in Crop Management) management of field crops. Disease thresholds have been
9:00 am Welcome and Opening Remarks ♦ Mike successful management techniques. What are the thresholds for Gray and Kevin Stejfey important field crop diseases? What does independent science tell us regarding the thresholds and prediction models for these 9:15 am Lessons from a “Quiet" 2006 Season—W hat diseases? Lies Ahead? 1:00 pm Identification and Management of Soybean Introduction * Todd Gleason Diseases + Glen Hartman
9:20 am Climate Patterns: Past, Present, and Future ♦ 1:25 pm Integration—The Key to Managing James Angel Fusarium Head Blight (Scab) in
9:35 am Crop Production + Emerson Nafziger Wheat ♦ Paula McMullen
9:50 am Weed Management + Aaron Hager 1:50 pm Fungicides on Hybrid Corn: Yield Impact of Foliar Disease Control + Gary Munkvold 10:05 am Questions and Answers 2:15 pm Application Strategies to Improve Crop
10:25-10:40 am Break ♦ South Lounge Health ♦ Robert E. Wolf
2:40 pm Questions and Answers 10:40 a m Rust Is Here, Now W hat? ♦ Suzanne Bissonnette Symposium B ♦ Seed and Soil: Some Basics of Crop Agro nomics ♦ Ballroom ♦ Mike Hellmer, Moderator 10:55 am Nematode Management + Terry Niblack (0.5 CCA credit in Soil and Water Management, 0.5 CCA credit in Nutrient Management, and 0.5 CCA credit in Crop Manage 11:10 am Insect Management ♦ Kevin Stejfey ment) 11:25 am Questions and Answers Even though 2006 was a relatively “quiet" year in terms of Although the 2006 growing season was relatively “quiet” and crop problems in crop growth and management, there is always more prospects were excellent, a review of prevailing conditions and to learn with regard to "managing the manageable” in order to pest issues always presents opportunities for learning. Problems keep yields moving up. This symposium will include a review of with crop development and pests developed, despite the general recent research on the related issues of corn roots, tillage, and goodness of the season, and agricultural issues changed or crop nutrition, and will conclude with a presentation on the ever- evolved, presenting the possibility for improvements. Panel critical issue of establishing the best possible stand. members will interact to address field crop issues in 2006—W hat 1:00 pm Tillage System Effects on Root Growth and happened? How can we learn from our experiences in 2006? Fertilizer Placement Considerations ♦ Could a good crop year have been better? A look back to look Rickard Cruse ahead. 1:35 pm Why is My Field Showing Potassium
11:45 a m -1 :0 0 pm Lunch, on your own Deficiency? + Fabian Fernandez
2:10 pm The Ideal Corn Stand + Emerson Nafziger
Symposium C ♦ Wheat Management in Illinois ♦ Rooms 314A and B ♦ Fred Kolb, Moderator (1.0 CCA credit in Integrated Pest Management and 0.5 CCA credit in Crop Management) Winter wheat acreage in Illinois has fallen by some two-thirds over the past three decades, due to yield and price instability and
2007 Illinois Crop Protection Technology Conference ♦ v ii to high yields of corn and soybean, with which wheat competes. 8:00 a m Impact of Glyphosate-resistant Palmer Good yields in recent years and more favorable prices in 2006 Amaranth on Southeastern Agriculture + have more people thinking about wheat. This symposium will Stanley Culpepper provide information on recent developments in wheat breeding 8:20 am Glyphosate-resistant Waterhemp: and management, including management of important pests. Our Experiences in Missouri ♦ 1:00 pm Fitting Wheat into Illinois Cropping Kevin Bradley Systems ♦ Emerson Nafziger 8:40 a m Predicting the Evolution and Spread of 1:25 pm Wheat Disease Management ♦ Glyphosate-resistant Waterhemp ♦ Patrick Gregory Shaner Tranel
1:50 pm Development of Fusarium Head Blight 9:00 am Preparing for the Inevitable— Resistant Wheat Varieties ♦ Fred Kolb A Prescription for Resistance ♦ Dawn Nordby 2:15 pm Managing Insects in Wheat: An Overview ♦ Doug Johnson 9:20 am Questions and Answers
Symposium E ♦ Insect Management Issues: 2:45-3:15 pm Break, South Lounge Did Events in 2006 Set Us Up for 2007? ♦ Ballroom ♦ David Feltes, Moderator Symposia A , B, and Crepeated concurrently (1.5 CCA credits in Integrated Pest Management) from 3:15-5:00 pm This session will provide management information for two old insect foes (European corn borers and western corn rootworms) Symposium A (repeated) ♦ Healthy Plants; Is Your Disease and two newer invasive insect pests (soybean aphids and western Threshold Damaged? ♦ Illini Rooms A and B bean cutworms). Aphids presented fewer challenges to Illinois Symposium B (repeated) ♦ Seed and Soil; Some Basics of producers in 2006; however, 2007 may be another story. Updates Crop Agronomics ♦ Ballroom on the latest research efforts at Iowa State University and the University of Illinois will be provided for this key insect pest. Symposium C (repeated) ♦ Wheat Management in Illinois + Western bean cutworms continued to expand their range Rooms 314A and B eastward during 2006. How significant is the economic threat posed by this new invader? W hat are the best management 5:00-6:30 pm IFCA-Sponsored Mixer approaches? These questions and others will be answered. Bt and Illini Union South Lounge non-Bt tactics can be used for western corn rootworms, western This mixer is sponsored by the Illinois Fertilizer and Chemical bean cutworms, and European corn borers. Management Association. It is intended for everyone to meet with speakers, considerations for economic insect control include: selecting the sponsors, and committee members in an informal atmosphere. most appropriate transgenic hybrid (single-, double-, or triple stacked), or not selecting a Bt hybrid; use of a seed treatment in a refuge; application of conventional insecticides (granular vs. liquid); and implementing the most appropriate refuge strategy (if Thursday Morning, January 4 Bt is used) for a given operation. More choices were available for insect control in 2006, with potentially more options available in Symposia D, E, and F run concurrently from 2007. Come prepared to challenge these speakers with your insect 8:00-9:45 a m management questions.
8:00 am Soybean Aphid Management: What Works Symposium D ♦ Glyphosate Resistance: It's Not Just Limited and What Doesn’t? + Matthew O’Neal to Crops Anymore + Illini Rooms A and B + Aaron Hager, Moderator 8:25 am Western Bean Cutworm and the Invasion of Illinois Corn: It’s Like Deja vu All Over (1.5 CCA credits in Integrated Pest Management) Again ♦ Marlin Rice
Glyphosate-resistant weed biotypes have become significant 8:50 am Transgenic Corn Rootworm Hybrids: challenges for weed management practitioners across many areas Assessing Performance in a Variant Western of the United States. At least two species of Amaranthus have Corn Rootworm Arena ♦ Mike Gray been confirmed resistant to glyphosate. Horseweed, lambsquar- ters, and giant ragweed are other annual weed species in which 9:15 am Seed-applied Insecticides, Soil Insecticides, glyphosate-resistant populations have been selected or are and Bt Corn: Their Roles in Corn suspected. This symposium will focus on the occurrence of Production ♦ Kevin Steffey glyphosate resistance in Palmer amaranth and waterhemp and 9:30 am Questions and Answers how glyphosate resistance may be spread across populations.
v ill ♦ 2007 Illinois Crop Protection Technology Conference Symposium F * Hie Influence of Organic Markets and Urban Thursday Afternoon, January 4 Perspectives on Agrichemical Applications ♦ Rooms 314A and B + Russet Higgins and Elizabeth Wahle, Moderators 12:00 n o o n - A light lunch will be provided to people 12:15 pm who attend the closing session. Lunches (1.0 CCA Credit in Professional Development and 0.5 CCA will be available in the South Lounge, credit in Integrated Pest Management)
Wal-Mart is selling more and more organic produce and grocery Closing Session ♦ Illini Rooms A, B, and C ♦ items. Celebrities and famous athletes repeatedly tout the “purity” Mike Gray, Moderator and “enhanced” quality of organic foods. Regardless of your personal feelings about organic foods, this segment is growing (0.5 CCA credit in Integrated Pest Management and 0.5 CCA rapidly and will influence the traditional commercial agrichemical credit in Professional Development) industry even in a large grain state like Illinois. Organic crops and Strengthening the Partnership with the Illinois' Agribusiness the increasing demographic of rural citizens who are generations Community removed from the farm are changing how custom applicators operate in many parts of rural Illinois. Learn what organic The longevity of this conference through almost six decades is a certification means and what it takes to maintain harmony with testament to the enduring partnership that exists among the organic producers and non-farm landowners. University of Illinois, University of Illinois Extension, and the agribusiness sector. The organizers of this conference value this 8:00 am Who’s Your Neighbor? + Jack Erisman relationship and hope to synergize this partnership by exploring new collaborative opportunities in this quickly evolving crop 8:20 am Managing the Risks of Custom Application: An Industry Perspective + Jean Payne protection arena. Dr. Wendy Wintersteen, Dean of the College of Agriculture, Iowa State University, will describe an innovative 8:35 a m Surviving on the Fence Between Emerald approach in Iowa (Corn and Soybean Initiative) that is designed City and Oz ♦ Donald Meyer to revitalize the important linkage between our land grant system and the agribusiness retail sector. Ultimately, this program aims 8:55 am Illinois Department of Agriculture to improve the implementation of relevant and research-based Perspective ♦ Gerald Kirbach crop protection information to producers. Following Dr. Winter- 9:15 a m Identifying and Protecting Organic Farms steen's presentation, Dr, Robert Hoeft, Head of the Department from Contamination with Prohibited of Crop Sciences, and Jean Payne, President of the Illinois Substances ♦ Cissy Bowman Fertilizer and Chemical Association, will offer their reactions and comments regarding this Iowa State University partnership with 9:35 am Questions and Answers Iowa retailers. Is this or a similar approach needed in Illinois? Please come ready to interact with these speakers and offer your 9:45-10:15 am Break, South Lounge insights.
12:15 pm Overview ♦ Mike Gray Symposia D, E, and E repeated concurrently 12:20 pm Is Extension Delivering Relevant and from 10:15-12:00 noon Effective Integrated Pest Management Corn and Soybean Programs? ♦ Symposium D (repeated) ♦ Glyphosate Resistance! Its Not Wendy Wintersteen Just Limited to Crops Anymore + Illini Rooms A and B 12:50 p m Reaction and Proposal—College of ACES, Symposium E (repeated) ♦ Insect Management Issues: Did UIUC; Illinois Fertilizer and Chemical Events in 2006 Set Us Up for 2007? ♦ Ballroom Association Symposium F (repeated) ♦ The Influence of Organic Markets Robert Hoeft, Head, Department of Crop and Urban Perspectives on Agrichemical Applications ♦ Rooms Sciences, University of Illinois at Urbana- 314A and B Champaign Jean Payne, President, Illinois Fertilizer and Chemical Association
1:15 pm Adjourn
2007 Illinois Crop Protection Technology Conference ♦ IX Kirbach, Gerald ♦ Manager, Permits and Downstate Field Program Participants Operations, Bureau of Environmental Programs, Illinois Department of Agriculture, Springfield, IL Angel, James ♦ Illinois State Climatologist, Illinois State Water Survey, Champaign, IL Kolb, Fred + Professor, Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL Ayers, Steve ♦ Extension Unit Educator, Champaign Extension Unit, University of Illinois Extension, Champaign, IL McMullen, Marcia ♦ Professor, Department of Plant Pathology, North Dakota State University, Fargo, ND Bissonnette, Suzanne ♦ Extension Educator, Integrated Pest Management, Champaign Extension Center, University of Illinois Meyer, Donald ♦ Unit Leader, McLean Extension Unit, University Extension, Champaign, IL of Illinois Extension, Bloomington, IL Black, Kevin ♦ Insecticide and Fungicide Manager, Growmark, Munkvold, Gary ♦ Associate Professor, Department of Plant Inc,, Bloomington, IL Pathology, Iowa State University, Ames, IA Bowman, Cissy ♦ CEO, Indiana Certified Organic, Clayton, IN Nafziger, Emerson ♦ Professor, Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL Bradley, Kevin ♦ Assistant Professor, Division of Plant Sciences, University of Missouri, Columbia, MO Niblack, Terry ♦ Professor, Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL Bretthauer, Scott + Extension Specialist, Pesticide Safety Education, Department of Agricultural and Biological Engineering, Norby, Dawn ♦ Extension Specialist, Weed Science IPM, University of Illinois, Urbana-Champaign, IL Department of Crop Sciences, University of Illinois, Urbana- Champaign, IL Cruse, Richard + Professor, Department of Agronomy, Iowa State University, Ames, IA O’Neal, Matthew ♦ Assistant Professor, Department of Entomology, Iowa State University, Ames, IA Culpepper, Stanley + Assistant Professor and Extension Agronomist, Rural Development Center, University of Georgia, Paulsrud, Bruce ♦ Extension Specialist, Pesticide Applicator Tifton, GA Training and Plant Pathology, Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL Erisman, Jack + Producer, Pana, IL Payne, Jean ♦ President, Illinois Fertilizer & Chemical Association, Fernandez, Fabian + Assistant Professor, Department of Crop Bloomington, IL Sciences, University of Illinois, Urbana-Champaign, IL Reed, Rick + Member, Illinois Agricultural Aviation Association, Feltes, David ♦ Extension Educator, Integrated Pest Management, Mattoon, IL Quad Cities Extension Center, University of Illinois Extension, East Moline, IL Rice, Marlin ♦ Professor and Extension Specialist, Department of Entomology, Iowa State University, Ames, IA Gleason, Todd ♦ Media Communications Specialist, Information Technology and Communication Services, University of Illinois, Reifsteck, John ♦ Producer, Champaign, IL Urbana-Champaign, IL Runkle, Kevin ♦ Regulatory Affairs Manager, Illinois Fertilizer & Gray, Mike + Professor, Department of Crop Sciences, University Chemical Association, Bloomington, IL of Illinois, Urbana-Champaign, IL Shaner, Gregory ♦ Professor, Department of Botany and Plant Hager, Aaron ♦ Assistant Professor, Department of Crop Sciences, Pathology, Purdue University, West Lafayette, IN University of Illinois, Urbana-Champaign, IL Steffey, Kevin ♦ Professor, Department of Crop Sciences, Hartman, Glen ♦ USDA-ARS, Associate Professor, Department University of Illinois, Urbana-Champaign, IL of Crop Sciences, University of Illinois, Urbana-Champaign, IL Tranel, Patrick ♦ Associate Professor, Department of Crop Hellmer, Mike ♦ Agronomy Information Manager, Pioneer Hi- Sciences, University of Illinois, Urbana-Champaign, IL Bred International, Inc., Mahomet, IL Wintersteen, Wendy ♦ Dean and Director, College of Agriculture, Higgins, Russel + Extension Educator, Integrated Pest Iowa State University, Ames, IA Management, Matteson Extension Center, University of Illinois Wahle, Elizabeth ♦ Extension Educator, Horticulture, Extension, Matteson, IL Edwardsville Extension Center, University of Illinois Extension, Hoeft, Robert ♦ Head, Department of Crop Sciences, University Edwardsville, IL of Illinois, Urbana-Champaign, IL Wolf, Robert E. ♦ Extension Specialist, Application Technology, Johnson, Douglas ♦ Professor, Department of Entomology, Kansas State University, Manhattan, KS University of Kentucky, Princeton, KY
X ♦ 2007 Illinois Crop Protection Technology Conference Lessons from a “ Ouiet” 2006 Season— What Lies Ahead? S j Climate Patterns: Past, Present, and Future Angel
ver the years, there has been increasing concern The precipitation pattern in Illinois can be described in about climate change, especially as the result three periods. The first period is from the 1840s to 1900s of human activities such as introducing more and is distinguished by increasingly drier conditions. In greenhouseO gases and aerosols into the atmosphere and fact, 1901 is the driest year in the historical record, with changing the land surface. An examination of global only 26.32 inches of rain, 64% of normal. The second mean temperatures shows an increase over time that period is from the 1900s to the 1960s, when precipitation may be attributed to these activities. W hat about Illi overall remained drier than the modern day. The third nois? Have we seen significant changes in the climate of period is from the 1960s to the present, when conditions Illinois? Long-term temperature, precipitation, drought, rapidly became wetter. Most of this increase in precipita and snowfall records will be presented. In addition, this tion during the third period occurred in spring, summer, paper will focus briefly on the three most recent growing and fall but not winter. Other studies have indicated that seasons. The outlook for the coming growing season the number of heavier rainfall events during the 20th will be discussed during the presentation, but will not century has increased in conjunction with the increase in be discussed here for reasons provided elsewhere in this precipitation in Illinois (e.g., Karl and Knight 1998). paper. I use the term “normal” to refer to an average for The shift from drier conditions in the early portion of the the period 1971-2000. This is standard practice for 20th century to the wetter conditions since the 1960s is describing the modern-day climate of a site or region. reflected in the drought record for Illinois, as well. An The traditional seasons discussed in this paper are winter examination of the statewide Palmer Drought Severity (December—February), spring (March-May), summer (June—August), and fall (September-November).
Past Climate Patterns Annual Patterns Figure 1 is the time series of average annual precipitation in Illinois expressed as a percentage of normal. The first 20 years of the record from 1840 to 1860 are represented by only one to four stations. More stations were added each year so that by the 1880s, the number of stations ranged from 20 to 30, depending on the year. The 20th century records were represented by 50 to 60 high-quality, long-term records. As a result, the precipitation record from 1840 to 1860 may be viewed as less certain, whereas the precipitation record from the 1880s to the present FIGURE 1 • Average annual precipitation in Illinois, as is viewed as more certain. expressed as a percentage of normal.
2007 Illinois Crop Protection Technology Conference ♦ 1 Index (PDSI), a measure of monthly drought conditions based on both temperature and precipitation and available only since 1895, indicates that eight “extreme ’ droughts (indicated by a PDSI value of 4 or less) occurred in the record from 1895 to 1965. The lowest PDSI on record was -6.9 in July 1934. Since 1965, only the drought of 1988 qualified as a statewide extreme drought. The drought of 2005 did not qualify because it was confined primarily to northern and western Illinois, whereas south ern Illinois enjoyed near-normal precipitation. Even so, the core drought area attained PDSI values of 4 or less, achieving extreme drought status. Ilinois State Water Survey Figure 2 is the time series of average annual temperatures ------Actual — S-yr Moving Average j in Illinois. As with precipitation data, average annual FIGURE 3 • Average winter (December-February) temperatures in the early years are reconstructed from temperature in Illinois. only a handful of stations. However, by the 1870s, the number of stations increased, along with the confidence in the series. Overall, the temperatures in the 1800s were However, temperatures during the decades in the 1930s cooler than they are today. From the 1890s to the 1930s, and 1950s are still considered warmer than those of the the statewide temperature warmed by about 2,5°F. From most recent decade. 1930 to 1980, the temperatures cooled by about 2°F. Since 1980, the temperature has warmed by about 1°F. Seasonal Patterns The net result is that Illinois temperatures warmed by Most of the change in annual temperatures over time approximately 1°F over the historical record from 1840 occurred during the winter months (Figure 3). The to 2005. The temperature changes discussed here are in sequence of warming, cooling, and then warming iden general terms to illustrate the major patterns— the exact tified in the annual temperatures is clearly seen here. years and magnitudes of change vary slightly depending Furthermore, the magnitudes of change are considerably on the analysis used. From Figure 2, the most significant larger. For example, the range of winter temperatures in warming to take place in Illinois was in the late 1800s the historical record is about 17°F, compared to only 8°F and early 1900s and occurred before greenhouse gases in the annual temperatures. Even so, the overall increase were believed to have any impact on the climate. The in winter temperatures over time is only about 1°F in modest warming of the past two decades reverses the cooling trend that apparently ended around 1980.
ffinois State Water Survey
------A c tu a l------5-yr Moving Average
FIGURE 4 • Average spring (March-May) temperature FIGURE 2 • Average annual temperature in Illinois. in Illinois.
2 ♦ 2007 Illinois Crop Protection Technology Conference Slinois State Water Survey — Actual----5-yr Moving Average
------A c tu a l------5-yr Moving Average FIGURE 7 • Average snowfall-season (September-May) FIGURE 5 • Average summer (June-August) snowfall in Illinois. temperature in Illinois. was about 2°F warmer than pre-1930. The period after the Figure 3, Since 1895, the coldest winter occurred in 1978 1950s was cooler, as well, but not as cool as the pre-1930 (19.6°F); the warmest winter was in 1932 (37.0°F). period. Another interesting feature of summer records is the low year-to-year variation in temperature during the The sequence of warming, cooling, and then warming in decades of the 1960s and 1970s. The period since 1980 the annual and winter temperature records is absent in has seen a return to higher year-to-year variation. Since spring records (Figure 4), However, temperatures have 1895, the two warmest summers on record have been in increased by approximately 1°F since 1895, The coolest 1936 (78.6°F) and 1934 (78.2°F). The coolest summer on spring on record was in 1960 (46,6°F); the warmest record was in 1915 (69.2°F), although it should be noted spring was in 1977 (57,3°F). that 2004 was the fourth coolest summer, at 70.4°F, For summer (Figure 5), the most unusual feature is the For fall (Figure 6), the temperatures exhibit no long-term sudden warming that occurred in the decades from the trend. In recent years, the period from 1998 to present 1920s to the 1930s. It is probably no surprise that the has been a little warmer than the period from 1980 to summers of the 1930s during the so-called Dust Bowl 1997. Since 1895, the warmest fall was in 1931 (60.3°F); were the warmest on record. A secondary peak occurred in the coldest fall was in 1976 (48.6°F). the mid 1950s. This period from the 1930s to the 1950s Another feature of the winter climate of Illinois is snow fall. A reconstruction of the average snowfall in Illinois is shown in Figure 7. There are no long-term trends in snowfall. However, the snowy winters of the late 1970s and early 1980s are outstanding in the record. That period coincided with the trend toward colder winters (Figure 3). Snowfalls since the early 1980s have been noticeably less. Considering that the period-of-record average snow fall is 20.1 inches, 15 of the last 20 snow seasons have been below average. Snowfall ranged from 9.4 inches in 1920-1921 to 44.5 inches in 1978-1979. From an agricultural point of view, the trend toward more precipitation and fewer droughts in the past 30 Blinois State Water Survey to 40 years is probably the most favorable development. | ------Actual — 5-yr Moving Average However, the flip side is that the increased precipitation includes increases in heavy rainfall events, resulting in FIGURE 6 • Average fall (September-November) temperature in Illinois. more flooding and more soil erosion. During the last
2007 Illinois Crop Protection Technology Conference ♦ 3 century, most of the large temperature changes have the Midwest, the drought in 2005 was largely confined occurred in winter. Temperatures during spring, summer, to Illinois. As a result, the impact on commodity prices and fall show no significant warming. Despite the nega was minimal. Despite unfavorable growing conditions in tive impacts of some recent years, such as the drought of areas of Illinois, yields of corn and soybean were better 2005, conditions during the growing season in the later than expected. Factors contributing to this occurrence portion of the historical record have been much better included better plant genetics; the lack of extremely hot than the series of hot, dry summers in the 1930s. weather in July and August; timely rains, especially from the four tropical storms that moved up from the Gulf of Current Climate Patterns Mexico; and starting the growing season with excellent The 2004 Growing Season soil moisture (Kunkel et al. 2006). Favorable weather during the 2004 growing season helped The 2006 Growing Season produce record yields in corn, soybean, sorghum, and The weather for the 2006 growing season was generally alfalfa. Obtaining record yields in four main crops in Illi favorable for Illinois, except for areas around Quincy and nois in a single year has never happened before and reflects to the east of St. Louis. Those two areas experienced per the remarkably favorable growing conditions of that year. sistently dry conditions throughout the growing season, Spring conditions in 2004 could be described as warm although not as severe as occurred in 2005. Otherwise, (3°F above normal) with a dry April (1.87 inches) between Illinois experienced near-normal temperatures and rain a wet March (4.27 inches) and May (6.88 inches)— ideal fall in the spring and summer. Spring temperatures were for field work in April. Summer temperatures were 3°F only 1.6°F above normal, with rainfall of 12.24 inches below normal with near-normal rainfall (12.11 inches, (0.97 inch above normal). Summer temperatures were 0.55 inch above normal). Research conducted at the 0.8°F above normal with rainfall of 11.10 inches (0.45 Illinois State Water Survey (Changnon and Changnon inch below normal). 2005) documented an unusually high number of clear days that summer. More clear days combined with cooler Outlook for the 2007 Growing Season temperatures and ample soil moisture meant that plants were near their maximum productivity, with minimum The National Weather Services Climate Prediction Center stress, all summer. The end of the growing season was (http://www.cpc.noaa.gov) produces the official forecast capped by a September that was both warm (1.7°F above or outlook for the next month and for 3-month periods normal) and dry (2.48 inches below normal), which aided for the next 13 months. Because these are updated twice in the rapid maturing and dry down of the crops. a month for the 1-month forecast and once a month for the 3-month periods, the outlooks will not be discussed The 2005 Growing Season in this paper. At the time of writing (October 2006), a moderate El Nino event had developed in the Pacific The 2005 growing season was preceded by the sixth Ocean basin. The strength and impacts of this event will wettest January on record, with 5.39 inches of precipita be discussed during the presentation. tion. This resulted in widespread flooding of streams and rivers, as well as a considerable amount of water standing References in field. This proved to be im portant in the forthcoming drought because the key components of the hydrological Changnon, S. A., and D. Changnon, 2005. Unique 2004 Growing system (soil moisture, lakes, streams, and groundwater) Season Weather Conditions Resulting in Record High Crop Yields were fully recharged. The flooding was followed by the in Illinois and the Midwest ISW S DCS 2005-01, Illinois State second driest spring statewide since 1895. Concerns about Water Survey, Champaign, IL, 19 pp. drought began to emerge in late May and June, as soil mois Karl T.R., and R.W. Knight, 1998: Secular trends of precipita ture was being depleted faster than normal. By summer, tion amount, frequency, and intensity in the USA. Bulletin of a significant drought had developed in northern and the American Meteorological Society, 79:231-241. western Illinois, as rainfall deficits for 2005 had reached Kunkel, K.E. (ed), J.R. Angel, S.A. Changnon, R. Claybrooke, 8 to 12 inches below normal in those areas. Meanwhile, S.D. Hilberg, H.V. Knapp, R.S. Larson, M. Palecki, R.W. southern and parts of central Illinois had received some Scott, and D. Winstanley, 2006. The 2005 Illinois Drought. relief from the unprecedented passage of four tropical ISW S IEM 2006-03, Illinois State Water Survey, Champaign, storms. Unlike the drought in 1988, which spanned IL, 80 pp.
4 ♦ 2007 Illinois Crop Protection Technology Conference Lessons from a “ Ouiet” 2006 Season— What Lies Ahead? Crop Production Emerson D, Nafziger
fter the “trying” year of 2005 in some parts of both corn and soybean “redeveloped” green leaf area in Illinois, there was real relief when the weather in late August, and fill conditions in early September were 2006 was favorable for timely planting of corn. very good, with yield prospects improving as maturity PlantingA took place at a rapid pace, with corn planting was delayed. Corn harvest started more or less on time, in Illinois 73% complete by the end of April and 95% but soybean harvest was delayed. complete by May 14. Then the weather turned damp Predicted yields of corn and soybeans in Illinois in 2006 and cool, causing delays in soybean planting and some are second among Illinois yields, trailing only 2004, serious stand challenges in both corn and soybeans. This with corn currently estimated at 169 and soybean at 50 was followed by temperatures in the 90s for about a week bushels per acre (NASS, November Crop Report). Corn at the end of May, which caused a growth spurt in crops yields by crop reporting district show more than normal that were emerged, brought wheat maturity on rapidly, consistency from north to south, with the exception of and allowed a fast finish to planting. Emergence was very the Southwest Crop Report District, which experienced good in most fields. some very dry weather (Table 1). Some of our early data Summer weather had its normal ups and downs in Illinois, show some greater than average yield loss when corn but most areas got enough rainfall to keep crops growing follows corn in the drier areas of western Illinois, which, fairly well. There was enough dry weather in June, and a along with dry weather in spots, may have contributed lack of excessive rainfall, such that root development was to lower overall yields in some areas. good as roots grew deeper into soil moisture. Dry weather W hat “troubles in paradise” did we see in Illinois in the was also good for wheat, which was harvested early, with mostly good year 2006? the highest statewide yield (67 bushels per acre) ever in Illinois. Rainfall patterns were mixed, though, with parts ♦ There was a rash of reports of unusual plant symptoms of western Illinois receiving less rainfall in June and July in corn in late June, especially from areas in western than in 2005, while other areas had above-normal rainfall Illinois, including some fields where it was dry and in July. Growing degree day accumulations were close some where moisture was adequate. Plants showed to normal, so with the early planting, corn pollination unusual bends in stems, with some stem pith discol started a little early. Pollination was successful in most oration in streaks. No definitive cause was found for fields but was followed by high temperatures in the last this problem. Stinkbug was invoked as one possibil half of July into early August. This caused some kernel ity, but the distribution of the problem suggests that abortion, and “tip-back," or unfilled kernels at the outer this was not the primary cause. Most affected fields end of the cob, was common. seem to have yielded well, indicating that symptoms seen before pollination did not carry through to yield August weather was very good in most areas, with loss. adequate rainfall and moderate temperatures. Concerns about high temperature and drought stress lessened as
2007 Illinois Crop Protection Technology Conference * 5 TABLE i • Corn yield projections by Illinois Crop Bt traits seem to have a positive influence on corn Reporting District. Projections released in early stands. Seed-treatment insecticides are also helping November lowered corn and soybean yields slightly, to soybean stands. 169 and 50, respectively (source: NASS). ♦ Dry weather effects in some areas reminded us that Corn Soybean corn and soybeans are not in fact “drought proof,” District 2005 2006 2005 2006 despite improvements in vigor, roots (probably), and bu pier acre canopy health that have helped keep plants growing when its dry. Still, there were some reports of much Northwest 140 185 48 57 lower yields in some corn-following-corn fields in Northeast 129 178 43 52 some areas, and it is clear that increasing acreage of continuous corn will present ongoing challenges. West 141 166 46 49
Central 146 185 51 57 ♦ One of the most unusual and vexing problems in 2006 was the scattered incidence of “short ear syndrome,” East 158 179 51 55 aka “beer-can ears.” After seeing this problem on and West Southwest 151 165 46 48 off for more than 10 years, we still do not have a full East Southeast 139 160 45 50 picture of cause and effect with this disorder. In 2006, it showed up very unexpectedly in some high-yield- Southwest 133 127 41 42 potential fields in northern Illinois, including some Southeast 130 147 43 45 that were irrigated. We have variously invoked the IL 143 171 46.5 51 possibility of herbicide effects, foliar fungicides, low temperatures, genetics, and just about everything else. To date, no clear picture has emerged. We do know ♦ Despite generally good corn stands, cutworms reduced that this disorder cost up to 100-bushel yield losses in stands and yields in some fields. Some seedling anthrac- some fields, and it's clearly a problem that needs some nose was also noted. Seed-treatment insecticides and attention.
6 ♦ 2007 Illinois Crop Protection Technology Conference 'eed Management Aaron G. Hager
t seems likely that some weed control practitioners Increased Frequency of Biennial Weed would agree that describing the 2006 season as Species “quiet” is appropriate, whereas others perhaps would Anecdotal observations suggest that Illinois farmers are argueI “raucous” might better capture the sentiments of encountering more challenges from biennial weed species. the season. Regardless of whether you consider weed W eed species that complete their life cycle over a 2-year management in 2006 as quiet, raucous, or something period may find a home in agronomic production systems else completely, several occurrences and observations in which tillage is reduced or eliminated. from the 2006 season warrant discussion in this “season recap” and perhaps deserve heightened attention now, at A contemporary example of a such a biennial weed species the outset of 2007. is poison hemlock (Conium maculatum). Poison hemlock is commonly found in pastures and along railroad rights- Crop Injury from Herbicide Carryover of-way, roadsides, and other nondisturbed areas but is becoming increasingly common in reduced- and no-till The 2006 weed management season began where it corn and soybean fields. Farmers and other weed control left off in 2005, on a dry note. Soil moisture levels were practitioners who have experienced difficulty controlling depleted in several areas of Illinois in 2005, including poison hemlock in the spring prior to crop planting may hard-hit areas north of Bloomington. We had revisited want to consider investigating fall application as a pos the topic of herbicide carryover toward the end of 2005 sible way to improve overall success. A fall application and speculated that rotational crop injury might occur would be better suited for targeting rosette-stage plants, from reduced dissipation of herbicide residues. Our and higher herbicide rates may provide better control speculation was confirmed when instances of crop injury with fewer planting restrictions, compared with lower caused by herbicide carryover began to occur. application rates in the spring. Although the reports of rotational crop injury spanned several herbicide active ingredients and products applied A New Weed Control Paradigm for Corn during 2005, soybean injury caused by carryover of Widespread adoption of glyphosate-resistant soybean mesotrione-containing products was frequendy reported. varieties, with a concomitant use of glyphosate for weed In contrast to the often-observed pattern of crop injury control, has become the norm for Illinois soybean farmers. (i.e,, injury generally confined to overlaps, field“hot spots,” Heretofore limited adoption of glyphosate-resistant corn etc.) caused by herbicide carryover, many instances of hybrids provided a disruption of the“glyphosate-only cycle” mesotrione carryover encompassed large areas of soybean across many Illinois acres, but that began to change in fields (sometimes entire fields). Discoloration or yellowing 2006. Estimates of the percentage of acres planted with of soybean leaves was quite evident but often subsided glyphosate-resistant corn hybrids varied during 2006 following a precipitation event. Effects (if any) on soybean but generally were above 30%. seed yield are, at this time of writing, largely unknown.
2007 Illinois Crop Protection Technology Conference ♦ 7 One may speculate whether the adoption of glyphosate- inhibiting herbicide with glyphosate often improved resistant corn hybrids will'transform” corn weed control control of volunteer corn compared with glyphosate alone, programs into something resembling contemporary but it seemed that all not ACCase-inhibiting herbicides soybean weed control programs. In other words, will total performed with equivalent efficacy. postemergence weed control programs in corn become as common as they are in soybeans today? W ithout much Horse weed or Marestail? doubt, there were some who attempted to manage weeds The academic debate over the “correct” name of the in glyphosate-resistant corn in a manner similar to the species took a backseat to the very real problem of poor way they manage weeds in soybeans (i.e., by using a marestail control with glyphosate, undoubtedly attributed single postemergence application of glyphosate). Under (in many instances) to glyphosate-resistant populations. the “right” conditions, it is altogether likely that excellent Because glyphosate use is pervasive both prior to plant weed control and corn yields can be achieved with this ing (i.e., burndown) and following crop emergence (i.e,, type of program. But this type of program also carries the postemergence in glyphosate-resistant varieties/hybrids), greatest risk for significant yield loss if weeds are allowed identification of horseweed populations from Illinois that to compete too long or if significant weed populations are not adequately controlled by glyphosate necessitates emerge after the initial glyphosate application and are that farmers consider alternative options to control these left uncontrolled. populations. Chemical options may not always provide Thus, total postemergence weed control programs can an adequate level of control, but preplant tillage (when be viable options, but close and careful attention must be feasible) can greatly reduce marestail populations that given to the timing of the initial application as well as to are present prior to planting. accurately assessing the need for subsequent applications, Illinois farmers are poised to plant a significantly higher Inconsistent Weed Control with percentage of their corn acres in 2007 with glyphosate- Glyphosate resistant corn hybrids compared with previous years. Similar to past seasons, several weed species seemed to Although this technology offers some enticing advantages, challenge the “one product for all needs” reputation of it is unlikely to solve all perceptible weed management glyphosate. Control of common lambsquarters, water- problems. Keep in mind that although this technology hemp, volunteer corn (described previously), and velvetleaf represents a new tool for weed control, the principles of following postemergence applications of glyphosate could weed control in glyphosate-resistant corn hybrids are the be described as ranging from extremely effective to highly same as they are in conventional corn hybrids. erratic. Weed si^e, application rate, and myriad other variables almost certainly influenced the level of weed Volunteer Corn in Soybeans control achieved, but suffice it to say that the efficacy Many cornfields across the state “greened up” following the of glyphosate against several weed species has declined. 2005 harvest, not because of weed growth but because of More and more weed control practitioners discovered the'second” corn crop of the season (i.e., volunteer corn). that morningglory species can be difficult to control with Although some of the corn seed was lost because some glyphosate alone, and several posed questions about which seed germinated in the fall and some seed died during tankmix partners can help address this weakness. the winter months, volunteer corn was a common weed problem in Illinois soybean fields during 2006. Glyphosate Late-Season Observations is very effective for control of volunteer corn in soybeans; Cursory observations made during weed collection cam however, many weed control practitioners reported that paigns late in the 2006 season suggested that waterhemp, glyphosate provided poor control of volunteer corn in marestail, volunteer corn, giant ragweed, and shattercane 2006. Several of these instances occurred in fields where were (depending on location) the most frequently encoun glyphosate-resistant corn had not been planted in 2005, tered weed species overtopping soybean canopies. Water- causing some to ponder whether the volunteer corn was hemp generally has held this distinction in past seasons, resistant to glyphosate, and, if so, how this trait came but several other species vied for this infamous status at to occur in a field where no glyphosate-resistant corn the end of2006. Hophornbeam copperleaf, although not previously had been planted. Tankmixing an ACCase- visible above the soybean canopy, nonetheless was very
8 ♦ 2007 Illinois Crop Protection Technology Conference prevalent in many harvested corn and soybean fields of a delay in maturity (some described the symptoms as central and south-central Illinois. similar to those of green stem) and a reduced number of pods toward the top of the plant stem. These symptoms There were scattered reports of delayed soybean matu did not occur on every field so treated, and speculation rity that appeared to follow late-season applications of was made that some varieties may be more prone than glyphosate. Typically, soybean treated with late "clean-up” others to these symptoms. applications, made close to the R2 or R3 stage, exhibited
2007 Illinois Crop Protection Technology Conference ♦ 9 Lessons from a "Ouiet” 2006 Season- What Lies Ahead? Rust Is Here; Now What? Suzanne Bissonnette
hat started out as a fairly average disease The finding of soybean rust in southern Illinois was scenario in the 2006 growing season certainly not unexpected. Spore deposition models indicated the ended up with a bang. distinct probability of development of soybean rust in W Illinois. Infection by soybean rust in Illinois so late in Soybean rust was positively diagnosed in eight Illinois the season had no impact on our 2006 soybean crop. counties in 2006. It was first confirmed on October 13, Information that was collected on the extent of this 2006, on a sample collected from a soybean research outbreak, however, greatly facilitates research on soybean plot at the U of I Dixon Springs Agricultural Research rust and aids in the refinement of predictive models for Center in Pope County. University of Illinois Plant Clinic soybean rust. director Nancy Pataky and USDA-ARS soybean plant pathologist Dr. Glen Hartman observed the sample Again in 2006, Illinois had sentinel plots throughout and sent it to the national mycologist at USDA-ARS the state to aid in the early detection of soybean rust. in Beltsville, Maryland, for positive confirmation and Thirty-nine sentinel soybean rust plots were established species verification, as indicated by the national proto in the state. Most plots were soybean, but kudzu (Pueraria col for handling of first soybean rust samples in a state. lobata), field pea (Pisum sativum), dry beans (Phaseolus Soybean rust was then confirmed in seven additional vulgaris), and mung beans (Vigna radiata) were also counties— Massac, Hardin, White, Alexander, Johnson, observed and sampled. Double-cropped soybean sentinel Pulaski, andjefferson. plots also were planted in southern Illinois. Cooperators were the University of Illinois, University of Illinois So as not to test anyone's geography memory too much, Extension, and Southern Illinois University. Plots were for the most part the counties with confirmed soybean located throughout Illinois on research stations and rust are the southernmost counties in Illinois. The on commercial and private fields. Plots were sampled distribution of rust in Illinois and other states can be weekly during the season and analyzed by personnel at seen on the national soybean rust Web site (Pest Infor the University of Illinois Plant Clinic. Results of samples mation Platform for Extension and Education, PIPE), and crop progress were reported on the PIPE national http://www.sbrusa.net. To see what happened in late Web site. The plots were funded by a combination of 2006, select a date, such as October 27, 2006, on the grant monies from the USDA Risk Management Agency side menu of the site. (RMA), Illinois Soybean Association, Illinois Depart Detection of soybean rust in southern Illinois counties ment of Agriculture, and the North Central Soybean in October 2006 was a serious reminder that the disease Research Program. isn’t going to hang out only on the Gulf Coast. Addition Anticipation of soybean rust and participation in the ally, just one weather event moved the pathogen up the sentinel plot program resulted in documentation of Mississippi River Valley, not only to southern Illinois the disease progress of other foliar soybean diseases in but also as far as Lafayette, Indiana. the state, as well. Several foliar diseases were observed
IO ♦ 2007 Illinois Crop Protection Technology Conference including Septoria brown spot, frogeye leaf spot, bacterial (University of Illinois Extension resources for soybean rust blight, bacterial pustule, and downy mildew. Samples were can be ordered online at http://www.PublicationsPlus. incubated and verified at the University of Illinois Plant uiuc.edu or by calling 800-345-6087.) Clinic. These other foliar diseases are not new to Illinois; Also, a new Extension Report on Plant Disease #1002, however; documentation of trends and the spread of “Characteristics of Fungicides for Field Crops’’ (h ttp :// foliar diseases was eye opening, particularly with regard www.ag.uiuc.edu/~vista/abstracts/al002.html) is an to the extent of bacterial blight this season. excellent resource when making decisions about using Information on soybean rust, rust management, fungicide fungicides. recommendations, and monitoring can be found through As you make your scouting and management plans for our soybean rust Web sites, http:// soyrust.cropsci.uiuc. next season, remember that part of our early detection edu and http://www.soybeanrust.org, as well as through plan in Illinois includes pre-screening of soybean foliar the national USDA Web site, http://www.sbrusa.net/, samples for rust. In Illinois, a specialised section of which also has additional information on good farming our University of Illinois Digital Distance Diagnostics practices documentation and insurance documentation Imaging (DDDI) system to aid in early detection of requirements through RMA. Asian soybean rust has been in place since 2004 for you Numerous other online and printed resources are avail to take advantage of quick sample pre-screening. Our able to aid in soybean scouting and disease management, DDDI system is essentially an online plant clinic, and, including with regard to soybean rust, our goal is rapid pre-screen ing and early detection of rust infected plants. Samples ♦ the news release series at http://www.ipm.uiuc.edu/ can be submitted to the University of Illinois DDDI fieldcrops/soybeans/diseases.html; system at your county Extension unit office. The results ♦ in-season articles in the Bulletin, http://www.ipm.uiuc. of soybean rust pre-screening via DDDI are available edu/bulletin; within a few hours. If the DDDI pre-screening appears + fungicide spray recommendations fact sheet, updated suspect, a plant sample is submitted to the U of I Plant on our crop science Web site, http://soyrust.cropsci. Clinic for verification. uiuc.edu/index.cfm In 2006, rust was not the only source for end-of-the-season ♦ North Central IPM Center’s soybean rust fact sheets, troubles. Green stem in soybean continues to present http://www.ncipmc.org/ alerts/soybeanrust.cfm harvest and yield concerns. Green stem symptoms can be a result of “green stem syndrome,” which still has no ♦ NCR 504 scouting brochure, http://www.aphis. known cause, or can be a symptom of bean pod mottle u sd a .g o v /p ublications/plant_health/content/ virus infection. Seedling and root diseases of soybean printable_version/SBR_IDcard_ll-04.pdf, also continue to be an issue for producers. Low-quality Soybean producers and scouts should have seed led to some germination problems in 2006. Because stem and pod diseases again impacted soybean in many ♦ a field crop scouting guide (Field Crop Scouting Manual, areas late in 2006 seed quality should be considered for U of I Extension publication number X880d); and the 2007 season. Cold germination tests for low-quality ♦ the reprinted and updated soybean disease pocket guide seed lots are more reliable indicators of performance than (.Pocket Guide to Soybean Diseases, U of I Extension warm germ tests for questionable seed lots. publication number C1380). Corn and wheat made it through the season relatively Also, new and specifically for soybean rust are unscathed by serious disease in 2006. Increasing levels of stalk rots were an issue in some areas of the state, ♦ a disease assessment tool (Soybean Rust Assessment particularly where injury from soilborne insects and Tool, U of I Extension publication number X881); drought were issues. O f particular concern were Diplodia and stalk and ear rot and Fusarium and anthracnose stalk ♦ a hand lens for soybean rust scouting endeavors (folding rots. In southern Illinois, late-season gray leaf spot and pocket magnifier, 20X, U of I Extension item number southern rust were evident. Diseases of wheat last year X882). were mainly caused by viruses associated with aphids
2007 Illinois Crop Protection Technology Conference + 11 and some fungal leaf blights. Scab was not a big problem rust. Let's keep in perspective that rust is a disease that this past season. can be managed with appropriate and timely fungicide applications. And remember that monitoring does take So, our best plant disease lesson from the “nearly quiet” a more diligent effort than we have been accustomed to 2006 growing season was that preparation, training, pre for soybean production. screening, and vigilance really did work to detect soybean
12 ♦ 2007 Illinois Crop Protection Technology Conference Lessons from a “ Ouiet” 2006 Season— What Lies Ahead? Nematode Management
* , ow;-T';.. " ||i ■#. s i 'W s #c- -ASicHVx^V-T-A'\* 4^ «stpf§^Ctv *v l i S3§§§$aj|s£^' Terry - ' L Niblack
006 was a pretty good year for corn and soybean, Nematology 101: The Background with lots of big, beautiful root systems and little Unlike the populations of many insects and pathogens, evidence of widespread disease. However, those big, a population increase of nematodes during the current beautiful root systems suggest that there was plenty of year may not affect yields. For most nematode-host pairs, food for root-feeding nematodes. On average, nematode yield is dependent on the number of nematodes present populations increased enormously in both soybean and at planting. Nematodes present at planting are the ones corn in 2006. This increase will have an impact on 2007, that infect the developing seedlings, and, if infection is especially for those who choose not to rotate crops. high enough, root growth will be restricted, affecting every following growth stage and eventually causing decreased yields. For example, the data in Figure 1 show the soybean cyst nematode (SCN) population densities in different areas of the same field, according to samples taken at harvest. The obvious conclusion from looking at this chart is that SCN populations increase yields—the higher the number of eggs, the higher the yield. However, the real relationship is revealed with data from the same field, sampled in April about 2 weeks before planting, shown in Figure 2—higher SCN populations at plant ing decrease yields. One other lesson to take from Figures 1 and 2 is that if an SCN-susceptible variety is planted, then the lower 6,000 12,000 20,000 the SCN population at planting, the higher it will be SGN eggs/100 cc soil (Oct.) at harvest. Because of those big, beautiful root systems FIGURE 1 • The numbeT of SCN eggs/100 cc soil from mentioned previously— more food, more nematodes. samples taken at harvest, compared with the yield The relationship is shown in Figure 3, of soybeans from the sampled plots. All samples and W hat all of this means is that nematode populations will yield measurements were taken from different areas be higher in 2007 than they were in 2006. of the same field planted to the same SCN-susceptible soybean variety. The egg numbers represent the final SCN population density measured in the same plots SCN in 2006 shown in Figure 2. According to the calls I received and reports I heard from around the state in 2006, two things commonly happened in SCN-infested fields this year:
2007 Illinois Crop Protection Technology Conference ♦ 13 60 standing water, very few fields had symptoms of SCN infestation, except in southern Illinois. ♦ Many soybean producers are discovering that their “SCN-resistant” soybeans are suffering yield loss caused by SCN. This could be the result of two things that are not mutually exclusive: first, the variety may not be resistant; and, second, the SCN population may have adapted to resistance. Based on our 2005-2006 survey, we know that 84% of the soybean fields in Illinois are infested with SCN, and 5,000 3,000 1,000 we also know that more than 75% of those SCN popula SCN eggs/100 cc soil (Apr.) tions already have adapted at some level to the resistant varieties we have available. Soybean producers should FIGURE 2 • The number of SCN eggs/ioo cc soil from samples taken at planting, compared with the yield make an extra effort to keep an eye on the SCN popu of soybeans from the sampled plots. All samples and lations in their fields— and to choose soybean varieties yield measurements were taken from different areas carefully. The Variety Information Program for Soybeans of the same field planted to the same SCN-susceptible (V IPS, http://web.aces.uiuc.edu/VIPS) database can soybean variety. The egg numbers represent the be an enormous help in that regard. initial SCN population density measured in the same plots shown in Figure 2. Corn in 2006 In 2006, for the very first time, more soil samples from ♦ No symptoms were seen in heavily infested SCN cornfields than from soybean fields were submitted to fields except when other seedling diseases also were the University of Illinois Nematology Lab for analysis. present. There may or may not be any specific interac This was an alarming development, suggesting we need tion between SCN and other seedling diseases, but to ramp up our educational and scouting efforts for corn the stresses of excess moisture and nematode infec nematodes. Remember that‘corn nematodes” can refer to tion resulted in plenty of circular patches of stunted, any of several different nematode species (unlike SCN). yellow plants with rotting root systems, reflecting areas The symptoms usually are completely nonspecific (yellow of standing water. In areas without short periods of ing, stunting) and may be associated with root rotting. As in previous years, we strong recommend that cornfields be sampled routinely for nematodes because the prob lems seem to be increasing in frequency each year. We nematologists in the Corn Belt think there are three main reasons why corn nematode problems are increasing: ♦ The new tools being used in IPM programs may actu ally be increasing nematode problems. The shift away from soil insecticides to neonicotinoid seed treatments or to genetically engineered hybrids may allow nema tode populations to increase more than they were able when soil insecticide use was more widespread.
5,000 3,000 1,000 ♦ The increase in no- or minimum-till production allows SCN eggs/100 cc soil (Apr.) the build-up of nematode species that are sensitive to soil disturbance. FIGURE 3 • The relationship between number of SCN eggs at planting and number of SCN eggs at harvest ♦ The increase in corn-on-corn production will definitely (from the data presented in Figures i and 2) shows that affect the nematode populations, in a positive way SCN populations tend to be higheT at harvest in plots for nematodes but in a negative way for corn produc that had lower numbers at planting. tion.
14 ♦ 2007 Illinois Crop Protection Technology Conference All corn fields have plant-parasitic nematodes in them. Outlook for 2007 That does not mean that all cornfields suffer yield loss Lessons from the past show that seasons with good caused by nematodes, but it will pay off in the long run growing conditions contribute to bumper crops of to know which nematodes are in each field and how their nematodes for the next season. Nematode management populations change over time. Sampling once every 3 years should not be at the bottom of the list for production of corn (6 years in a corn-soybean rotation) is a good concerns in 2007. standard practice that should be encouraged.
2007 Illinois Crop Protection Technology Conference ♦ 15 Lessons from a “Ouiet” 2006 Season— What Lies Ahead? Insect Management ,, Kevin L. Steffey and Michael E, Gray
nsect and mite pests of Illinois field crops were numer Insects and Corn Production, 2006 ous and active in 2004 and 2005, so we were due for Despite generally cooler and wetter conditions in 2006 a “quieter” year with respect to insect pest problems. than in 2005, corn planting got off to another early start InI general, insect pest numbers were fewer and insect in 2006, especially in western counties. The accumula activities were reduced in 2006, with some exceptions. tion of growing degree days (GDD) in April was above However, there were enough significant occurrences average, so corn emergence and development generally and issues in the insect world of 2006 that an overview were quite good. Although emergence of corn was com should provide ample opportunities for improving our promised somewhat in some areas by dry soils (western understanding and implementation of insect manage Illinois) and heavy rains in late April and early May, ment strategies. early-season growing conditions for corn were good. This report is a synopsis of insect management issues in Consequently, early-season subterranean insect pests Illinois and some other areas of the Midwest in 2006, caused few problems. There were numerous reports of with some explanations for what happened and some large numbers of white grubs in the spring, but there prognoses for 2007. We refer you to articles published were very few reports of injury caused by the grubs. We throughout the year in the Bulletin (http://www.ipm.uiuc. know now that most of the white grubs observed in the edu/bulletin) for more detailed discussions of each of the spring were Japanese beetles. issues described in this report. For ease of discussion, the The numbers of black cutworm moths captured in phero synopsis is separated by crop, although some pests were mone traps scattered throughout Illinois were larger in present in more than one crop (e.g., Japanese beetle). 2006 than they had been in several preceding years. Not This report does not cover in significant detail all of the surprisingly, there were more reports of economic cutting insect management issues addressed by Illinois producers damage caused by black cutworms in 2006 than in several in 2006. In fact, a caveat about the report is necessary. A preceding years, including some small pockets of heavy review of articles published in the Bulletin during the 2006 infestations. Reports of unacceptable control of black growing season revealed that crop development and insect cutworm larvae with the neonicotinoid seed treatments situations varied considerably among regions (northern, (especially Poncho 250) were relatively common. west central, east central, and southern) of Illinois. So, The numbers of reports of severe corn rootworm larval some of the information discussed in this report will be damage and large numbers of western corn rootworm representative of some areas and not necessarily repre adults were considerably fewer in 2006 than in 2005, sentative of others. Nevertheless, an overview should However, some fields were very badly damaged by corn provide insight for insect management issues that arise rootworm larvae in 2006, especially in corn planted after in localized areas or are more widespread in 2007. soybeans. The range of the variant western corn rootworm
16 ♦ 2007 Illinois Crop Protection Technology Conference continued to expand slowly into mid-southern counties some counties in Indiana, Michigan, Missouri, and Ohio. in 2006. Several fields of corn planted after soybeans Details regarding this trapping effort and more informa along the 1-70 corridor were severely damaged by corn tion about management of the western bean cutworm rootworm larvae. Although we did not conduct a formal are discussed in the paper Western Bean Cutworm and survey of corn rootworm larval injury in 2006, we became the Invasion of Illinois Corn: Its Like Deja vu All Over aware of significant rootworm larval injury in fields as Again, printed elsewhere in these proceedings. far south as Bond County. As the range of the variant Similar to occurrences in 2005, the “corn insect season” western corn rootworm expands, the use of rootworm in 2006 ended with many reports of infestations by ear- control products will increase accordingly. And, as we attacking insects. There was a tendency by many people stated last year, the use of yellow sticky traps to m onitor to attribute insect injury on corn ears to western bean for western corn rootworm adults in soybean fields falls cutworms. However, on close inspection, the culprits far short of the effort needed to make well-informed causing injury to the ears were usually corn earworms decisions about rootworm management. or fall armyworms. Accurate identification of these three Herculex RW com hybrids (HxRW) (event DAS-59122- ear-attacking corn insect pests will be crucial for develop 7, C ry34A bl/C ry35A bl) was commercially available for ing appropriate insect management plans. the first time in 2006. Also for the first time, we were We also observed large densities of second-generation able to compare the efficacy of HxRW corn hybrids European corn borers in several areas of Illinois late in and YieldGard Rootworm (YGRW, event M ON 863, the season, especially in western counties. Results from Cry3Bbl) corn hybrids in our standard corn rootworm our annual survey of second-generation European corn control trials located near DeKalb, Monmouth, Perry, and borers are presented in Table 1. Population densities Urbana. Results from these trials are discussed in detail in (number of borers per 100 plants) increased noticeably the paper Transgenic Corn Rootworm Hybrids: Assess in many counties from 2005 to 2006. Interestingly, the ing Performance in a Variant Western Corn Rootworm statewide average number of second-generation European Arena, printed elsewhere in these proceedings. Suffice it corn borers per 100 plants in Illinois in 2006 (23.24) was to say that the results from corn rootworm control trials lower than it was in 2005 (34.4). However, the average located near Urbana revealed that the variant western percentage infestation of corn plants was 24.2 in 2005 corn rootworm posed some challenges for transgenic Bt and 33 in 2006. Relatively large densities of second-gen corn hybrids in 2006. eration European corn borers were evident in the West Pollination again was threatened in 2006 by extremely and West Southwest crop reporting districts (73.77 and large numbers of Japanese beetles. This recurring pest will 76.88 corn borers per 100 plants, respectively). O f the 498 be discussed in more detail in this paper in the section fields surveyed, 244 (49%) of the fields had 0% infesta “Insects and Soybean Production, 2006.” tion of European corn borer larvae, whereas 75 (15%) of the fields had between 76% and 100% infestation of In 2005, western bean cutworm moths were captured European corn borer larvae (27 of498 fields [5.4%] had in pheromone traps in several counties, especially in 100% infestation). northwestern Illinois, and as far east as Will County. In 2006, we increased our vigilance for western bean Insects and Corn Production, 2007 cutworm, a pest that has continued to spread eastward in the Corn Belt. W ith the help of University of Illinois Some events in the corn insect world in Illinois probably Extension personnel and Pioneer Hi-Bred International seem preordained: agronomists, we established an extensive network of ♦ The distribution of the variant western corn rootworm western bean cutworm traps in almost every county of probably will continue to expand southward and Illinois. Entomologists from several other states also westward in 2007, established western bean cutworm pheromone traps, and all of the capture information was reported on an ♦ The western bean cutworm likely will gain more of a Iowa State University-sponsored Web site, http://www. foothold in Illinois in 2007. ent.iastate.edu/t rap/westernbeancutworm. Western ♦ Japanese beetles likely will threaten pollination in many bean cutworm moths were captured in many counties areas of Illinois in 2007, although predicting where is in Illinois and Wisconsin for the first time, and also in not easy.
2007 Illinois Crop Protection Technology Conference ♦ YJ TABLE i • Results of the 2006 fall survey for second-generation European com borer larvae.
Counties1 and Percentage of European corn Counties1 and Percentage of European corn Crop Reporting plants infested, borer larvae per Crop Reporting plants infested, borer larvae per Districts 2001 100 plants Districts 2001 100 plants Bureau 26 25.6 Calhoun 40 67.4 Jo Daviess 12 25.2 Christian2 35 28.8 Mercer 9 23.0 Greene 63 104.0 Ogle 1 0.0 Madison 44 99.2 Whiteside 4 3.6 Montgomery 50 105.0 Winnebago 10 12.8 Morgan 57 124.0 Pike 44 39.6 Northwest 10 15.03 Sangamon 38 47.0 DeKalb <1 0.4 West Southwest 46 76.88 Kendall 6 8.8 LaSalle 28 29.6 Clark 57 77.2 McHenry 17 19.8 Coles 25 22.2 Will 14 5.4 Crawford 31 40.2 Effingham 30 40.2 Northeast 13 12.8 Marion 24 4.6 Adams 81 131.8 Shelby3 30 35.8 Fulton 43 80.4 East Southeast 33 36.70 Knox 24 23.4 McDonough 15 30.4 Jackson 0 0.0 Schuyler 35 63.2 Monroe 10 9.6 Warren 34 113.4 Pulaski-Alexander 0 0.0 Washington 20 21.8 West 39 73.77 Southwest 8 7.85 Logan 25 48.8 Macon 32 25.4 Franklin 2 0.0 McLean 21 34.2 Massac 0 0.0 Peoria 36 53.0 Saline 16 10.4 Woodford 42 59.8 Wayne 11 13.4 White 35 22.4 Central 31 44.24 Southeast 13 9.24 Champaign 22 8.0 Iroquois 10 10.2 STATE 33 23.24 Livingston 12 31.8 Vermilion 22 22.8 Unless otherwise indicated. 10 randomly selected fields were sampled in each county. East 17 18.2 217 randomly selected fields were sampled. 311 randomly selected fields were sampled.
However, none of these events is surefire. There are many continue to use soil-applied insecticides for control of factors that cause insect populations to ebb and flow over soil-inhabiting insects, especially corn rootworm larvae, time, and these factors (most often weather) can change and many producers will continue to rely on seed-applied any forecasts we make. Nevertheless, plans for manage insecticides (e.g., Cruiser, Poncho) for control of subter ment of corn insects in 2007 likely have been made by ranean insects. However, the efficacy of seed-applied most corn growers, so an overview is worthwhile. insecticides against corn rootworm is not reliable, and the efficacy against some secondary insect pests (e.g., black Management of Corn Insects in 2007 cutworms) was called into question in 2006. The number of tools for insect control available to corn The percentage of corn acres planted to transgenic Bt corn producers continues to increase. Many producers will for rootworm control will increase once again. YGRW and
18 ♦ 2007 Illinois Crop Protection Technology Conference HxRW corn hybrids both will be planted in 2006, and Throughout the year, we heard reports of large numbers we assume that Syngenta’s Agrisure RW (event MIR604, of bean leaf beetles in other midwestern states, especially mCry3 Aa) corn hybrids also will be commercially available Iowa, Minnesota, and Wisconsin. However, although in 2007* Although we still have much to learn about the there were a few pockets of large numbers of bean leaf use of transgenic corn for rootworm control, reports of its beetles in Illinois, infestations of bean leaf beetles were efficacy are mostly very positive. Nevertheless, some ques not widespread. In addition, we have not had the inci tions about the impact of transgenic corn on rootworm dence of bean pod mottle virus (vectored by the bean leaf development and behavior linger. Incidents of significant beetle) in Illinois that soybean producers in Iowa have injury to the roots of transgenic corn late in the summer experienced recently. (i.e., August) must continue to be investigated. Since the discovery of the soybean aphid in the Midwest In addition to the transgenic Bt corn hybrids for control in 2000, soybean insect management has not been the of rootworms, YieldGard Corn Borer, Herculex I, and same. This insect has captured our attention like no other Agrisure CB corn hybrids provide protection against insect pest in soybeans in the Midwest. European and southwestern corn borers. Herculex I also Soybean aphids began to show up early (mid-June) in will control black cutworms and western bean cutworms. soybean fields in Illinois in 2006, but densities of this We anticipate more acres of these types of Bt corn will be insect built up relatively slowly during the summer and planted in Illinois because of concerns about European reached near-threshold levels (250 aphids per plant) only and southwestern corn borers and about western bean very late in the season. Most people indicated that few cutworms. A lot more acres of'stacked” corn hybrids (i.e,, natural enemies were observed. When winged soybean corn hybrids with transgenic traits for control of corn aphids began leaving soybean fields in search of their rootworms and corn borers and for glyphosate resistance overwintering host (buckthorn), a network of suction or tolerance) also will be planted in 2007. These corn traps in the Midwest began capturing some of the winged hybrids seem to have everything most growers would aphids. We have learned from past experience that the need for insect and weed management. However, their numbers of aphids captured in suction traps in the fall widespread use without implementing the recommended may have some bearing on the potential for soybean and regulated resistance management strategies could aphid outbreaks the following year. When the numbers result in serious consequences. of aphids captured are high, there is potential for large infestations of soybean aphids the following year. W hen Insects and Soybean Production, 2006 the numbers of aphids captured are low, there is less of Soybean production got off to a much slower start than a threat of large infestations of soybean aphids the fol corn production in 2006. As a result of rainfall in late lowing year. However, the presence or absence of natural April and early May, less than 50% of the soybean acres enemies (e.g., multicolored Asian lady beetle) and the had been planted by mid-May. Soybean development in weather play significant roles in determining soybean 2006 was generally slower and later than in 2005, aphid numbers during any given year. There were few insect problems in soybeans in Illinois Based on the flight of soybean aphids in the fall of 2006, in 2006. The biggest threat was posed by enormous the prospects for infestations of soybean aphids are rela numbers of Japanese beetles defoliating soybeans in July, tively good for 2007, The numbers of winged soybean The largest populations of Japanese beetles occurred in aphids captured in suction traps in the Regional Soybean southern Illinois, where many fields were treated twice for Aphid Suction Trap Network (http://www.ncpmc.org/ control of the insect. Scattered areas throughout central traps/index.cfm) were particularly large in Indiana. In Illinois also had extremely large numbers of Japanese addition, the every-other-year cycle of soybean aphids beetles. People likened driving through swarms of Japa (i.e., high densities in odd years, low densities in even nese beetles to driving through a hail storm. Fortunately, years) seems to suggest that we should remain vigilant the standardized percentage defoliation thresholds for in 2007. ... all chewing insects (30% defoliation before bloom, 20% defoliation during bloom through pod fill) are reliable Insects and Soybean Production, 2007 thresholds for Japanese beetles. The focus of insect management programs for soybeans in 2007 will justifiably be on soybean aphids, with bean
2007 Illinois Crop Protection Technology Conference ♦ 19 leaf beetles and Japanese beetles also receiving attention. paper is one way to offer a little forewarning for next In fact, with an increasing amount of data indicating year. Fortunately, aphids have many natural enemies, that seed-applied insecticides (e.g„ Cruiser, Gaucho) and aphid populations are very susceptible to weather effectively control early season bean leaf beetles and extremes. But these aphid species should be added to the delay the onset of heavy infestations of soybean aphids, list of more commonly occurring insect pests in alfalfa we anticipate that more soybean producers will rely on and wheat, ju st in case. these insecticidal seed treatments as part of their overall In alfalfa, both the pea aphid (Acyrthosiphon pisum) and insect management program. We still are not convinced the cowpea aphid (Aphis craccivora) occurred in unusually that the insecticidal seed treatments are cost effective for large numbers in some alfalfa fields in Illinois in 2006. soybeans, but the added insurance against insect injury The pea aphid occurs in alfalfa fields in Illinois every is attractive to many producers. year, but usually at very low levels. And their numbers The continued concern about the occurrence of Asian are usually held in check by natural enemies. The cowpea soybean rust in Illinois will encourage many produc aphid, on the other hand, is a relatively recent addition ers to scout soybean fields regularly and frequently, an to the list of potential insect pests of alfalfa in Illinois, activity that should improve decision making for insect and its repeated occurrence in alfalfa fields over the past management. However, we believe there will be some few years bears watching. Both of these insects use their incentives for soybean producers to mix insecticides with piercing mouthparts to suck fluids from alfalfa plants, either fungicides or herbicides (e.g., Roundup) or both to and large numbers of these aphids can cause yield loss. “control” all pests at once. Under most circumstances, this The cowpea aphid is a greater threat to alfalfa production mixing of pesticides is unnecessary, and the widespread than the pea aphid. application of so many pesticides could have unintended In wheat, large numbers of bird cherry-oat aphids (Rbo- consequences. We urge carefully planned decisions for palosipbum padi) were discovered in many fields in the anyone assessing the need for any of these pesticides for spring of2006. This aphid species is not uncommon and soybean pest management in 2007. frequently is observed in wheat fields in Illinois. Bird cherry-oat aphids can vector the barley yellow dwarf One Final Note— Aphids in Alfalfa and virus. Wheat, Too Some aphid species were more noticeable than usual in both alfalfa and wheat fields, so their mention in this
2 0 ♦ 2007 Illinois Crop Protection Technology Conference Soybean Rust: The First Three Years
G len Hartman
his paper provides an update of the current samples from 18 counties representing 70 fields. Samples situation of the occurrence of soybean rust were considered positive for rust if urediniospores were (.Phakopsora pachyrhizi) in the United States, observed under a dissecting microscope. A few of these T specifically in Illinois in 2006, and an overview of somesamples also were tested with a molecular assay and found of the research activities* Soybean rust was reported in positive for the fungus. O f the 70 fields, 30% had rust the continental United States in Louisiana in the fall finds representing a total of 93 rust positives or Samples season of 2004 (Schneider et al* 2005)* Since then, rust were considered positive for rust if urediniospores were was reported in 15 other states (http://www.sbrusa.net) observed under a dissecting microscope. A few of these including Illinois in 2006 (Hartman et al, 2007). The samples also were tested with a molecular assay and first report of the disease occurring on another host in found positive for the fungus. O f the 70 fields, 30% had the United States was on kudzu in Quincy, Florida, in rust finds representing a total of 93 rust positives, or 4% 2004 (H arm on et al. 2005). The introduction of the rust of the leaf samples collected. The number of uredinia fungus into the continental United States was thought be ranged from 1 to 66 uredinia per leaflet. carried via Hurricane Ivan, which hit the U.S. mainland Since the introduction of soybean rust in the United in September 2004 (http://www.ceal.psu.edu/ivan04. States, there has been an increase of research activity. htm). This started soon after the first report of rust in Hawaii In 2005, the fungus was first reported in Florida (h ttp :// in 1994. A soybean rust workshop was held in 1995 that www.sbrusa.net), where it was believed to survive the brought together researchers in the United States who winter on kudzu that remained green below the frost had experience with rust and laid the foundation for line. At the end of 2005, rust was reported in nine states subsequent research direction for soybean rust research (Kentucky, North Carolina, and Texas were new reports). in the United States (Sinclair and Hartman 1995). In 2006, the fungus was again first found in Florida and Before soybean rust hit the continental United States, was reported from Virginia to Texas and from Florida a review in 2003 outlined the importance of the disease to Illinois in 255 counties in 15 states as of November and evaluated the risk of rust to the U.S. soybean crop 6,2006 (http://www.sbrusa.net). Although most of the (Miles et al. 2003a). The following sections summarize occurrences were reported late in the season, the spread some of the research in the United States since 2004. This of rust in 2006 was greater than 2005, is not a comprehensive review; instead, it highlights what has been published in three main areas of research that Specifically in Illinois, rust was found in eight counties in includes pathogen biology, host resistance, and fungicide 2006. The first report was in Pope County (Hartman et al. management. 2007). Between this first sample (October 10,2006) and the last sample (October 22,2006), there were 2,176 leaf
2007 Illinois Crop Protection Technology Conference ♦ 21 Biology of Phakopsora pachyrhizi collected in 2001. In greenhouse tests, susceptible reac tions to P. pachyrhizi generally resulted in tan-colored Urediniospore Survival lesions containing 1 to 14 uredinia varying greatly in It is well known that fungal spores are particularly sensitive size within individual lesions. On these same genotypes, to ultraviolet (UV) wavelengths of solar radiation. In a resistance was typified by 0 to 6 small uredinia in reddish study conducted jointly between scientists in the United brown to dark brown lesions. Phakopsora meihomiae, a States and in Paraguay urediniospores were exposed to less aggressive rust pathogen, produced reddish brown natural sunlight for different durations (Isard et al. 2006). to dark brown lesions with 0 to 7 uredinia, regardless Measurements of total solar irradiance (0.285-2.8 pm) of soybean genotype. This kind of research explains the predicted spore germination as much as UV measure virulence diversity of this pathogen and may explain the ments did (0.295-0.385 pm). Spores exposed to doses lack of durability in soybean lines identified with resis of solar (> 28 MJ m-2) and UV radiation (>1 MJ m~2) tance. Further work on virulence diversity of U.S, isolates did not germinate. The proportions of the spores that is in progress at the N SR C under a U SD A -A PH IS and germinated were a linear function of solar irradiance (R2 Illinois Department of Agriculture permit. = 0.83). The relationship between spore viability and exposure to solar radiation is important to the soybean Telia rust aerobiological model that provides North American One of the questions in the United States was whether soybean growers decision support for managing soybean the fungus could produce telia. In the fall of 2005, telia rust (http://www.sbrusa.net). Further work on spore were diagnosed based on visual observation followed by germination from spores collected from fields indicated PCR confirmation on leaves of kudzu in central Florida that germination was as low as 1% and up to 99%, (H arm on et al. 2006).Telia were noted as dark brown to depending on the time and location of the collection black flecks on the abaxial leaf surface intermingled with (Beck et al. 2006). abundant tan to light brown uredinia. From 200 leaflets, 143, or 72%, had telia. The number of telia ranged from Movement of Spores a few scattered telia per leaflet (1 per cm2) to many (73 Three locations were monitored for spore movement per cm2). Telia were approximately the same diameter from epidemics at various stages of development using as uredinia but were appressed to the leaf surface and rotorods and passive traps for 6 to 10 days each in 2005 pigmented. The importance of telia, teliospores, and (Beck et al, 2006). Based on spore counts from rotorods, basidia remains elusive because no alternate host has spore release increased after leaves dried, peaked during been found. To date, telia have been reported to occur midday, then tapered off toward the evening. Rainfall only in Florida. events reduced spore release for a 24- to 48-hour period. Spores enumerated on passive trap slides indicated that Host Range spores dispersed in the direction of prevailing winds at The host range of the soybean rust fungus is known to lower than expected rates (3 of 22 total observation days). be broad (Sinclair and Hartman 1995). Native legume Further research on monitoring and predicting spore species in the United States have not encountered P. movement and viability is critical to the development pachyrhizi, Several studies were conducted in 2005 and use of accurate forecasting systems. to evaluate the host range of the fungus. In the field (Quincy, Florida), leaves of Phaseolus coccineus (scarlet Evaluation of Isolates runner bean), P. lunatus (lima bean), and P vulgaris Except for USDA-ARS Fort Detrick containment facili (kidney bean) had rust lesions when grown adjacent to a ties located at Frederick, Maryland (Bonde and Peterson rust-infected soybean field (Lynch et al. 2006). Uredinia 1995), there has been little effort to compare a world col counts ranged from 2 to 43 per 2-cm2 area of leaf samples. lection of P. pachyrhizi isolates. One recent study (Bonde Additional hosts were discovered after being evaluated et al. 2006) compared the virulence of P. pachyrhizi isolates under greenhouse containment facilities at Fort Detrick from Asia and Australia and P. meihomiae from Puerto (Lynch et al. 2006). Further work is in progress under Rico and Brazil, collected as much as 30 years earlier, with field conditions to determine what native legumes may isolates of P. pachyrhizi from Africa or South America be hosts for P, pachyrhizi.
22 ♦ 2007 Illinois Crop Protection Technology Conference TABLE i • Rust survey from Illinois counties starting with samples taken from October 10 through October 22,2006.
No. of fields Percentage of No. of leaves No. of leaves Percentage of County sampled1 fields with rust2 sampled3 with rust4 leaves with rust5 Alexander 7 43 279 2 0.7
Edwards 2 0 59 0 0 Franklin 1 0 68 0 0 Gallatin 7 0 181 0 0 Hardin 2 100 61 15 25 Hamilton 1 0 24 0 0 Jackson 1 0 45 0 0
Jasper 2 0 89 0 0
Jefferson 3 33 50 11 22 Johnson 9 78 238 14 6 Knox 1 0 45 0 0 Madison 5 0 100 0 0
Massac 7 14 216 15 7 Pope 6 50 119 28 24 Pulaski 5 20 179 6 3 Saline 1 0 25 0 0 Union 2 0 78 0 0
White 5 20 148 1 0.7 Williamson 3 0 172 0 0 Totals/Means6 70 30 2176 93 4
‘Two of these fields represent kudzu sites (Madison and Massac counties) and one clover (Jasper County), and two represent experimental plots (Pope County). Percentage of fields in a county with rust (number of fields positive/total number of fields sampled* 100). 3Total number based on sporulating uredinia. 4Total number of leaves (leaflets) sampled in each county. Percentage of leaflets with rust (leaflets positive/total leaflets sampled*100). 6Total number of fields, leaflet samples, and number with rust; mean percentage of fields and leaflets with rust.
Host Resistance Fort Detrick containment facilities. There were 3,512 out of 16,595 accessions screened that were selected for Soybean Germplasm a second round of evaluation, and, of those, 805 lines Some of the early screening results and the genetics of were selected as potential resistant sources for further resistance from previous decades were reviewed recently evaluations (Miles et al. 2006). Some of these lines have (Hartman et ah 2005). One of the recent objectives of been screened under field conditions in several locations, the USDA-ARS research on soybean rust was to evalu including in Attapulgus, Georgia, in 2005 and Paraguay ate the US DA Soybean Germplasm Collection located in 2006, and at multiple locations in the United States at the University of Illinois. These soybean accessions during the 2006 and 2007 summer seasons. In addition, were evaluated for resistance to P. pachyrhizi in the ARS a number of these lines have been crossed and are being
2007 Illinois Crop Protection Technology Conference ♦ 23 used for breeding, mapping, and genetic analysis (Hyten Effect of Timing of Fungicide Applications et al. 2007)...... Timing of fungicide applications may be critical in man Non-Soybean aging soybean rust and may, if used effectively, reduce the number of applications needed for economic benefit. Trials Some additional resistance sources have been identi were conducted in Paraguay (three locations) and in the fied in wild perennial relatives (Hartman et al. 1992), United States (four locations) (Mueller et al. 2005b). In In more recent studies, intersubgeneric hybrids have Paraguay, all three locations were infected with soybean been created between soybean and Glycine tomentella. rust; in two locations, rust significantly impacted yield. Amphiploid hybrid lines (2n = 118) were the result of Trials in the United States had no soybean rust in 2005 this hybridization, and, when tested at the ARS green but did in 2006. Treatments in each field included appli house containment facility at Fort Detrick, the amphi cations with triazole (Folicur), strobilurin (Headline), ploid hybrid clones retained the resistance that had been or a triazole-strobilurin combination (Quilt) applied found in the G. tomentella parent (Patzoldt et al. 2006). at various times and a nonsprayed control. In Paraguay, Re-instituting the backcross procedure, while testing for yields in two locations were significantly greater than resistance at every generation, could move the resistance the control for all treatments. Data from the 2006 U.S. gene(s) from G. tomentella to cultivated soybean. This locations with rust are currently being compiled, but, in research is ongoing and involves several research groups 2005 without rust, all but one treatment had significantly located at the NSRC. greater yield than the control at one location, and there was no statistical difference between the control and most Fungicide Evaluations treatments at two other locations. Fungicide Testing Acknowledgments Fungicide testing for control of soybean rust started in Support for the research on soybean rust includes the 2003 through a USDA program. The testing sites were Illinois Soybean Association, the North Central Soybean located where rust was a problem, including Paraguay, Research Program, the United Soybean Board, and South Africa, and Zimbabwe. Early reports of fungicide USDA-ARS and CSREES. I would like to thank the efficacy was compiled in 2003 (Miles et al. 2003b). In many people who were involved in this research and are addition to fungicide efficacy tests, fungicide application cited in the references section below. technology and timing of fungicides have been investigated both in the United States and in Paraguay. References Efficacy Studies Beck, L.F., M.R. Miles, T. A. Steinlage, and G.L. Hartman. 2006. Urediniospore release and escape from rust-infected soybean These experiments were completed in Paraguay, South fields. In Proceedings of the National Soybean Rust Sympo Africa and Zimbabwe from 2003 to 2006. The studies sium, November 29-December 1, 2006, St. Louis, MO. tested different fungicides using two and three applica tions. The first application started 50 to 69 days after Bonde, M.R., and G.L. Peterson. 1995. Research at the USDA- planting (DAP), followed by a second application approxi ARS Containment Facility on soybean rust and its causal mately 20 days after the first, and the third application agent, pp. 12-18. In Sinclair, J.B., and G.L. Hartman (eds). approximately 20 days after the second. Results showed Proceedings of the Soybean Rust Workshop, August 9-11, that almost all fungicides controlled rust compared to 1995. University of Illinois at Urbana-Champaign, College of the nonfungicide treatment, with yields often greater Agricultural, Consumer, and Environmental Sciences, National Soybean Research Laboratory, Urbana, IL. in fungicide plots than nonfungicide plots (Miles et al. 2005a-c; Mueller et al. 2005a). In some locations, the Bonde, M.R., S.E. Nester, C.N, Austin, C.L. Stone, R.D. Fred difference between the two-application program and the erick, G.L. Hartman, and M.R. Miles. 2006. Evaluation of three-application program was also significant, and these virulence of Phakopsora pachyrhizi and P. meibomiae isolates. differences showed a trend where the residual activity Plant Disease 90:708-716. differs among the products. In other locations in other Harmon, C.L., P.F. Harmon, T. A. Mueller, J.J. Marios, and G.L. years, trends varied depending on the onset and severity Hartman. 2006. First report of Phakopsora pachyrhizi telia on of rust. kudzu in the United States. Plant Disease 90:380.
*4 ♦ 2007 Illinois Crop Protection Technology Conference Harmon, P,E, M.T. Momol, J.J. Marios, H, Dankers, and C.L, Variety Testing Center, Zimbabwe, 2004-05. F & N Tests Harmon, 2005. Asian soybean rust caused by Phakopsora 6LFC004. pachyrhizi on soybean and kudzu in Florida (doi:10.1094/ Miles, M.R., G.L. Hartman, and C. Levy. 2005b. Control of PHP-2005-0613'01'RS), Plant Health Progress June 2005, soybean rust in a determinate cultivar at the Rattray Arnold Hartman, G.L., R.A. Hines, C.D. Faulkner, T.N. Lynch, and Research Station, Zimbabwe, 2004—05, F & N Tests 61: N. Pataky. 2007. Late season occurrence of soybean rust FC003. caused by Phakopsora pachyrhizi on soybean in Illinois. Plant Miles, M.R., G.L. Hartman, C. Levy, and W. Morel. 2003b. Disease (in press). Current status of soybean rust control by fungicides. Pesticide Hartman, G.L., M.R. Miles, and R.D, Frederick. 2005. Breeding Outlook 14:197-200. for resistance to soybean rust. Plant Disease 89:664-666. Miles, M.R., G.L. Hartman, N.C. van Rij, S, Tweer, E.D. du Hartman, G.L., T.C. Wang, and T. Hymowitz. 1992. Sources of Preez, and K.F. Lawrance. 2005c. Evaluations of fungicides resistance to soybean rust in perennial Glycine species. Plant for control of soybean rust in the cultivar ‘Prima 2000’ near Disease 76;396-399, Cedara, South Africa, 2004-05. F & N Tests 61:FC002,
Hyten, D.L., G.L. Hartman, R.L, Nelson, R.D, Frederick, V.C, Mueller, T. A., C. A. Bradley, C.D. Chesrown, C.H . Koger, E.R. Concibido, and P.B. Cregan. 2007. Map location of the Rppl Walker, W. Morel, M.R. Miles, and G.L. Hartman. 2005b. locus that confers resistance to Phakopsora pachyrhizi (soybean Response of soybean to timing of fungicide applications in the rust) in soybean. Crop Science (in press), presence and absence of Phakopsora pachyrhizi. In National Soybean Rust Symposium Proceedings, November 14-16, Isard, S. A., N.S. Dufault, M.R. Miles, G.L. Hartman, J.M. Russo, 2005, Nashville, TN, E.D. DeWolf, and W. Morel. 2006. The effect of solar irradi- ance on the mortality of Phakopsora pachyrhizi urediniospores. Mueller, T. A., M.R. Miles, G.L. Hartman, and W. Morel. 2005a. Plant Disease 90:941-945, Evaluation of fungicides for the control of soybean rust at Bella Vista, Paraguay, 2004-2005. F & N Tests 61;FC007. Lynch, T.N., J.J. Marios, D.L, Wright, P.F. Harmon, C.L. Harmon, M.R. Miles, and G.L. Hartman. 2006. First report of soybean Patzoldt, M.E., R.K. Tyagi, T. Hymowitz, G.L. Hartman, and rust-caused Phakopsora pachyrhizi on Phaseolus species in the R.D. Frederick. 2006. Soybean rust resistance derived from United States, Plant Disease 90:970. Glycine tomentella in amphiploid hybrid lines and derived fertile soybean lines. Crop Science (in press). Miles, M.R,, R.D. Frederick, and G.L, Hartman. 2006. Evaluation of soybean germplasm for resistance to Phakopsora pachyrhizi Schneider, R.W., C. A. Hollier, H.K. Whitman, M.E. Palm, J.M. (doi 10.1094/PHP'2006'0104'01-RS). Plant Health Progress, McKemy, J.R. Hernandez, L. Levy, and R. DeVries-Paterson. January 2006. 2005, First report of soybean rust caused by Phakopsora pachy rhizi in the continental United States. Plant Disease 89:774, Miles, M.R., G.L. Hartman, and R.D. Frederick. 2003a. Soybean rust: Is the U.S. crop at risk? APSnet feature, June 2003. Sinclair,J.B., and G.L. Hartman (eds), 1995. Proceedings of the (http://www.apsnet.org/online/feature/rust). Soybean Rust Workshop, August 9-11, 1995. University of Illinois at Urbana-Champaign, College of Agricultural, Miles, M.R., G.L. Hartman, and C. Levy. 2005a. Control of Consumer, and Environmental Sciences, National Soybean soybean rust in an indeterminate cultivar at the Gwebi Research Laboratory, Urbana, IL.
2007 Illinois Crop Protection Technology Conference ♦ 25 Integration—The Key to Managing Fusarium Head Blight (FHB = Scab) in Wheat Marcia McMullen
usarium head blight (FHB) of wheat, commonly Shaner 1994; Stack 1999). Recent research has provided called head scab, is a fungal disease that continues more information about these strategies. to cause yield and quality loss in all classes of wheat F Fungicides can be used effectively to reduce FHB. In tests across most regions of the United States, with billions of of more than 50 fungicides or fungicide combinations in dollars lost to producers and the wheat industry in recent Europe, reductions in FHB severity averaged between 55% epidemic years (McMullen et al. 1997; Nganje et ah 2004; and 60% with the best treatments (Mesterhazy 2003). Cowger and Sutton 2005). The disease also often results In the United States, uniform fungicide trials conducted in the presence of a fungal mycotoxin byproduct called across wheat classes and multiple states have resulted DO N (deoxynivalenol). U.S. food industry standards in FHB severity reductions averaging 40% to 60% and for DON and recent stricter guidelines for DON in D O N reductions averaging 26% to 38% (Hershman and wheat exports to Europe and Japan make control of this Milus 2003). Availability of an FHB disease forecasting disease even more important. The disease and the D O N Web site that provides risk information for 22 states, levels must be reduced to prevent further losses in wheat including Illinois, has been beneficial in helping producers acreage and small grain industries. make fungicide decisions. The address for this Web site The primary causal fungus of the disease, Fusarium is http://www.wheatscab.psu.edu. graminearum, not only causes head scab in small grains Rotational studies have shown the influence of previous but also causes stalk rot and ear rot in corn. In wheat, crops on this disease. In Indiana, it was shown that spore the results of FHB infection are yield losses, lowered test production of the fungus was about two times higher in weight, increases in damage, reduced market grade, and a wheat field with corn as previous residue compared to possible presence of the D O N mycotoxin, which further an adjacent wheat field on soybean residue (Shaner and reduces market price or makes the grain unmarketable. Buechley 2000). Rotations with corn, wheat, and soybean Infection in wheat primarily occurs at the flowering period in Minnesota (Salas and Dill-Macky2005) showed that of the crop, but the fungus can continue to colonize the FHB severity was highest with corn as the previous crop, grain head through early dough stage. Disease develop compared to a previous crop of wheat or soybeans. These ment and severity are primarily dependent on rainfall same authors also demonstrated that incorporation of the or high humidities at flowering and post-flowering of infected residue also reduced subsequent FHB severity. the wheat crop. Obst et al. (1997) demonstrated that corn in the rotation Because producers cannot predict or control environmen and the tillage practice following corn had large impacts tal conditions that may occur at this critical growth stage, on DON levels. other management strategies are needed. A number of Considerable effort among plant breeders has resulted management strategies have been demonstrated to reduce in great improvement in cultivar reaction to FHB in all FHB and DON, including use of fungicides, crop rota wheat classes. Dr. Fred Kolb, a wheat breeder with the tion, tillage, and tolerant cultivars (Sutton 1982; Bai and
26 ♦ 2007 Illinois Crop Protection Technology Conference University of Illinois at Urbana-Champaign, is presenting References information at this conference on response of current soft Bai, G., and G. Shaner 1994. Scab of wheat; Prospects for control. red. spring wheat cultivars to FHB. In North Dakota, a Plant Disease 78:760-766. spring wheat cultivar called Alsen, which has a Sumai-3 source of resistance to FHB, was released in 2001 and Cowger, C., and A. Sutton. 2005. The southeastern U.S. by 2004, occupied 37% of North Dakota spring wheat Fusarium head blight epidemic of 2003. Plant Health Progress acreage. In 2005, another cultivar was released with (http://www.ars.usda.gov/research/publications/ publications, several sources of FHB resistance. htm?SEQ_NOJL15=171662). However, under severe epidemics, an individual strategy Hershman, D.E. and E. A. Milus. 2003. Analysis of2003 uniform used alone, or even use of two strategies, cannot reduce wheat fungicide trials across locations and wheat classes, pp. 76-80. In Proceedings of the 2003 National Fusarium disease severity and D O N to levels required by the grain Head Blight Forum, Bloomington, MN. December 13-15, industry. For example, in 2005, when environmental con 2003. U.S. Wheat and Barley Scab Initiative, Michigan State ditions were extremely favorable for FHB in the Dakotas University, East Lansing, MI. and Minnesota, very susceptible spring wheat or winter wheat cultivars that were grown on soybean ground— and McMullen, M., R. Jones, and D, Gallenberg. 1997. Scab of wheat even treated with fungicides— still had high yield loss and and barley: A re-emerging disease of devastating impact. Plant high D O N . In 2005, it became very clear that single-based Disease 81:1340-1348. strategies for managing FHB in wheat could not be successful Mesterhazy, A. 2003. Control of Fusarium head blight of wheat in very favorable environments. A combination of strategies, by fungicides, pp. 363-380. In Leonard, K., and W. Bushnell, each building on the other, is required for achieving the best (eds). Fusarium Head Blight of Wheat and Barley. APS Press, management of FHB and for obtaining quality grain. St. Paul, MN.
Table 1 provides one example of how a combination Nganje, W,, S. Kaitibie, W.W. Wilson, F.L. Leistritz, and D. A. of practices reduced FHB severity and DO N levels in Bangsund. 2004. Economic Impacts of Fusarium Head Blight research trials in North Dakota in 2005, a year when in Wheat and Barley: 1993-2001. NDSU Agribusiness and environmental conditions were extremely favorable for Applied Economics Report No. 538, July 2004, 53 pp. the disease. Each practice alone would not have been suf Obst, A., J. Lepschy-Von Gleissenthall, and R. Beck. 1997. On the ficient to achieve the relative low D O N level. Additional etiology of Fusarium head blight of wheat in south Germany. research on the additive, or synergistic, effects of man Cereal Research Communications 25:699-704. agement practices are currently being evaluated through cooperative, multi-state projects of the U.S. W heat and Salas, B,, and R. Dill-Macky, 2005. Effect of residue management Barley Scab Initiative. and host resistance on the epidemiology of Fusarium head
TABLE i • Influence of management practices on Fusarium head blight (FHB) and deoxynivalenol (DON), North Dakota State University, across two North Dakota eastern research locations, Fargo and Prosper, 2005.
Actual FHB FHB management practice FHB reduction % severity index1 % D O N reduction % Actual DO N ppm None 0 40 0 10 Rotation alone: soybean residue instead of wheat 50 20 50 5 Rotation + Variety: Alsen (MR) rx instead of Reeder (S) rx 60 8 60 2 Rotation + Variety + Fungicide: Folicur fungicide at flowering instead of untreated 60 3.2 40 1.2
1 FHB severity index = incidence of tillers with symptoms x head severity on infected tillers/100.
2007 Illinois Crop Protection Technology Conference ♦ ZJ blight, pp. 144-146. In Proceedings of the 2005 National Stack, R.W. 1999. Fusarium head blight: Return of an old Fusarium Head Blight Forum, Milwaukee, WI, December problem, APSnet feature, May 1999 (http://www.apsnet. 11-13,2005. U.S. Wheat and Barley Scab Initiative, Michigan org/feature/FHB). State University, Hast Lansing, MI. Sutton, J.C. 1982. Epidemiology of wheat head blight and maize Shaner, G., and G. Buechley. 2000. Sampling spores of Fusarium ear rot caused by Fusarium graminearum. Canadian Journal of graminearum, pp. 182-186. In Proceedings of the 2000 Plant Pathology 4:195-209. National Fusarium Head Bight Forum, Brlanger, KY, December 10-12,2000. U.S. Wheat and Barley Scab Initiative. Michigan State University, East Lansing, MI.
28 ♦ 2007 Illinois Crop Protection Technology Conference Fungicides on Hybrid Corn Yield Impact of Foliar Disease Control Gary P. Munkvold lli- is iliiissa**
oliar diseases have been recognized as an economic While the 1990s saw wide adoption of fungicide use in problem on commercial corn for more than a corn seed production, fungicides in commercial hybrid Fcentury, and fungicides have been available for their corn were not widely adopted. The reasons for this dif control for several decades. However, throughout much ferential adoption are clear: the relatively low value of of the history of hybrid corn production, fungicides were corn grain compared to seed and the relatively lower not recommended and were very rarely used for foliar susceptibility of hybrids in general to yield loss from disease control. Interest in this form of foliar disease foliar diseases, compared to inbreds commonly used as management in corn heightened in 1993—1994, when seed parents. two events took place; an unusually severe outbreak of To use fungicides profitably in hybrid corn production, common rust (Puccinia sorghi) swept across the central it has been necessary to more carefully assess the risk Corn Belt, causing significant yield losses in hybrid corn of yield loss. Assessing this risk has only recently been and completely destroying some fields planted to inbreds aided by the development of modeling approaches for for seed production (Munkvold and Yang 1995); and the prediction of disease severity (Paul and Munkvold propiconazole (Tilt fungicide, Syngenta Crop Protec 2004,2005). These tools need to be coupled with infor tion, Greensboro, NC) was the first systemic fungicide mation about the relationship between disease severity approved for use on corn. and yield loss in order to make effective decisions about During the past 13 years, the corn fungicide situation using fungicides. There is a continual need for up-to-date has evolved rapidly; a number of new active ingredients information on these relationships as new fungicide active have received approval, and the use of fungicides in corn ingredients continue to be approved for use on corn. The seed production has become a routine practice. This situation is complicated by the potential for direct effects evolution was spurred initially by the demonstration in of some fungicides on plant physiology, independent of 1993 of very significant yield increases with the use of disease control. This aspect will be covered elsewhere propiconazole to control common rust, but it also was in these proceedings; this article focuses on the use of fueled by the emergence during the 1990s of gray leaf fungicides for disease control and yield benefits related spot (Cercospora zeae-maydis) as a significant economic to disease control. problem in corn grown in Illinois, Indiana, Iowa, and Nebraska, Most fungicide use on corn in subsequent Decision-Making for Fungicide Use on years has been targeted toward common rust or gray Hybrid Corn leaf spot, although northern leaf blight (Exserohilum Fungicide decisions for hybrid corn must take into account turcicum) is not uncommon and occasionally southern several risk factors. Using a simple disease threshold (or rust (Puccinia polysora) or northern leaf spot (Bipolaris economic injury level, EIL) alone is not sufficient. In zeicola) can be targets. most cases, economic injury levels (Pedigo 1999) have not been established for foliar diseases of corn. It can be
2007 Illinois Crop Protection Technology Conference + 29 difficult to apply these concepts to the management of corn ♦ tillage practices foliar diseases. Economic injury level calculation requires ♦ hybrid susceptibility and maturity knowledge of the amount of damage (yield loss) per unit of pest population (or disease severity) and knowledge of ♦ planting date the expected efficacy of the management input (Pedigo ♦ field productivity and corn prices 1999). It is assumed that these parameters and others are known with a high level of precision, and the economic ♦ fungicide and application costs injury level is calculated as a single value, not associated ♦ weather patterns with a probability. An action threshold is reached when it is estimated that actual injury will reach the EIL, and ♦ scouting observations (compared to a threshold) the management tactic is employed (Pedigo 1999). Field History, Previous Crop, Tillage Unfortunately, measurements of yield losses associated with specific corn foliar disease severity levels and mea Fields with a history of disease problems, corn on corn fields, and minimum tillage fields are at a higher risk surements of yield increases attributable to fungicide and more likely to benefit from a fungicide application. applications are not precise. Damage per unit of gray These three factors are all related to the potential for leaf spot severity can vary by as much as 100% between disease inoculum. Previous crop and tillage practices locations or hybrids (Jenco 1995). Calculation of EIL will affect the risk of diseases other than rusts. Field based on predicted disease control is not practical when history is related specifically to the am ount of inoculum damage per unit injury varies to such a great extent. that might be present from a previous disease outbreak, Another difficulty is that, because of yield variability but it also relates to the potential for fields to be prone within experimental fields, yield increases that appear to more frequent disease outbreaks due to geography or to exceed the cost of fungicide application frequently topography. are not statistically significant. For example, Ward et al. (W ard et al. 1997, 1999) calculated that a “break-even” Hybrid Susceptibility yield increase for fungicidal control of gray leaf spot The probability of using a fungicide profitably is directly under conditions in South Africa would be 259 kg/ha. related to hybrid susceptibility. A fungicide should not be However, they reported that, in some experiments, yield considered for moderately resistant or resistant hybrids. differences of more than 1,200 kg/ha were not statistically These hybrids are unlikely to benefit economically from significant. Similarly, in several studies performed in the an application. It may be appropriate to consider fungi United States, the least significant yield difference among cides with hybrids that are in the moderately susceptible treatments was greater than (by sometimes twice as much) to susceptible categories. the break-even yield increase (Lipps and Johnson 1998, 1999; Stromberg and Flinchum 1998,1999; Shaner and Hybrid Maturity and Planting Date Buechley 1999). These problems create a dilemma in development of disease management recommendations. Hybrid maturity and planting date are important in The economic justification of a fungicide application is relation to the timing of disease development. In most difficult to assess when the break-even yield difference is situations, later-planted fields and/or later-maturing not statistically significant. The following guidelines can hybrids can be more vulnerable to yield loss because they be useful for increasing the likelihood that a fungicide are still filling grain while disease development is peaking application will be profitable. in the late summer. Therefore, these later fields are more likely to benefit from a fungicide application. Typically, in the central Corn Belt, only one application can be considered economically feasible on hybrids, and Field Productivity and Corn Prices the best time to make the decision is when the disease is at very low levels at or near tasseling. Factors to consider W hen both field productivity and corn prices are higher, in the decision about using fungicidal control include the cost of a fungicide is more justifiable, and this infor mation should be considered in relation to fungicide and ♦ history of disease in the field application costs. ♦ previous crop
30 ♦ 2007 Illinois Crop Protection Technology Conference Weather Conditions Yield Impact of Fungicides on Hybrid Corn If you understand the optimal conditions for the diseases Most published data on yield benefits for fungicide in your area, you can judge whether the weather or weather applications on hybrid corn have targeted gray leaf spot. forecast is favorable for the disease. If temperatures are Published trials have been conducted most commonly conducive and there is plenty of humidity and/or rainfall, in Virginia, Indiana, and Iowa. Studies in Indiana have the probability of benefiting from a fungicide application focused on corn inbreds. Most reports are brief data goes up. summaries, but two more detailed studies illustrated the influence of hybrid susceptibility on the likelihood of Scouting Observations yield loss and subsequent likelihood of economic benefit from a fungicide application. Scouting serves several purposes in relation to foliar diseases. It provides information on the timing of initial Gorman et al. (1997) used inoculations and Tilt fungicide infection. The earlier the infection happens, the greater applications to measure the yield benefit of controlling the risk of yield loss, especially for fast-moving diseases gray leaf spot on hybrids with different levels of resistance such as the rusts. Scouting also provides a measure of in field trials conducted in Tennessee, Pennsylvania, how quickly the disease is developing and provides the Indiana, and Iowa in 1995 and 1996. They found mean basis for timing of fungicide applications. Strict disease yield increases of about 8.5% with Tilt applications thresholds, however, are not precise for determining the on moderately resistant hybrids and about 14.5% on need for a fungicide, and thresholds should be used only susceptible hybrids (Figure 1). The authors did not as one of several pieces of information in the decision. assess the profitability of the two Tilt applications. A Below is a general guide to disease thresholds for hybrids similar study was conducted in 2004-2006 by the same differing in disease susceptibility. author, investigating the yield increases due to control of southern corn leaf blight (Bipolaris maydis) with Quadris ♦ Susceptible or moderately susceptible hybrids—A fungicide (Syngenta Crop Protection, Greensboro, NC) fungicide application can be used profitably on these in Georgia, Similar results were obtained; moderately hybrids if the disease is present on the third leaf below resistant hybrids did not exhibit significant yield increases, the ear leaf (or higher) on 50% of the plants before but susceptible hybrids yielded significantly higher with tasseling. Quadris applications. ♦ Intermediate hybrids—A fungicide application can Munkvold et al. (2001) analyzed data from fungicide be used profitably on these hybrids only if conditions trials conducted in Iowa from 1995 to 1997 and assessed are very favorable for the disease. This is likely if the probability of profitable fungicide use under natural ♦ the field is in an area with a history of problems infection on several hybrids differing in susceptibility to with gray leaf spot or other disease; gray leaf spot. Treatments were compared using a Bayes ♦ the previous crop was corn, and there is 35% or ian inference method to calculate for each experiment the more surface residue; probability of achieving a positive net return with one ♦ the field itself has a history of problems with gray
leaf spot or other disease; 16 ♦ the disease is present on the third leaf below the 14 c ear leaf (or higher) on 50% of the plants before 12 tasseling; and TJ1 10 £ 8 tj ♦ the weather is warm and humid through July and a> 6 > August. 3? 4 + Moderately resistant or resistant hybrids—We do 2 not recommend using a fungicide on these hybrids. 0
FIGURE i • Yield increase resulting from gray leaf spot control in corn hybrids differing in resistance.
2007 Illinois Crop Protection Technology Conference ♦ 31 1995 1995b 1996 susceptible resistant susceptible 2 1995 1995b 1996 susceptible resistant susceptible 2 1996b 1996 1996b 1996b 1996 1996b
» Break-even B$10/Aprofit] FIGURE 2 • Yield increases from one application of Tilt fungicide to control gray leaf spot in Iowa field trials FIGURE 3 • Probabilities of profit from one application on corn hybrids differing in susceptibility in 1995 and of Tilt fungicide to control gray leaf spot in Iowa field 1996. tnals on com hybrids differing in susceptibility in 1995 and 1996. or two propiconazole applications, based on the mean yields and standard deviations for treated and untreated 4). Studies have been done annually in Virginia, with plots, the price of grain, and the costs of the fungicide sometimes dramatic results. Gray leaf spot pressure is applications. For one application, the probability ranged typically higher in Virginia than in the Corn Belt, and a from about 0.06 to more than 0.99, and exceeded 0.50 in susceptible hybrid is used to maximize differentiation of six of nine scenarios (specific experiment/hybrid). The fungicide products. In the Virginia studies, in contrast highest probabilities occurred in the 1995 experiments to the findings in Iowa, two applications frequently with the most susceptible hybrid, when yield increased result in significantly higher yields than one application. by 27 bu/A with a single Tilt application (Figures 2 and In 2001, a yield difference of more than 70 bu/A was 3). Probabilities were almost always higher for a single reported (Stromberg and Flinchum 2002), and the best application of propiconazole than for two applications. treatment was two applications of Headline. In 2002, We concluded that a single application of propiconazole the best treatment was two applications of Quadris frequently was profitable for gray leaf spot management + Tilt (similar to the current product called Quilt) in Iowa, but the probability of a profitable application (Stromberg and Flinchum 2003). In 2004, a difference was strongly influenced by hybrid susceptibility. The of more than 70 bu/A was again reported and the best calculation of probabilities for positive net returns treatments were two applications of Quilt (Stromberg was more informative than the standard approach of and Kenley 2005). In 2005, the best treatment was two determining significant differences among treatments in applications of Headline (Stromberg and Kenley 2006) terms of assessing the economic success of the fungicide (Figure 4). In most experiments, treatments including applications. other strobilurin products resulted in yields similar to the best treatment. In a Nebraska study in irrigated Since those studies were conducted, the standard fungi corn in 2005, yields were high in all treatments, and the cides used on corn have moved from the triazoles, such as Tilt, to fungicides in the strobilurin family, Quadris and Fleadline (BASF Corp., Florham Park, NJ) or formulations combining a triazole with a strobilurin, Stratego (Bayer Crop Science, Research Triangle Park, NC) and Quilt (Syngenta). Gray leaf spot has been the most common target of fungicide applications in pub lished studies on hybrids. In these reports, there have typically been one or two susceptible hybrids and no comparisons with moderately resistant hybrids. Studies Virginia Nebraska Virginia Virginia Virginia Iowa Iowa Iowa in Iowa from 1999—2000 demonstrated yield increases 2005 2005 2004 2002 2001 2000 1999 1997 of up to 20 bu/A with gray leaf spot control, and the best treatments were Tilt (1999, two applications) or FIGURE 4 • Yield increases due to gray leaf spot control single applications of Quadris (1999 and 2000) (Figure in hybrid corn in Virginia, Nebraska, and Iowa.
32 ♦ 2007 Illinois Crop Protection Technology Conference yield difference was 7 bu between the control and the Lipps, P.E., and A.L, Johnston. 1998. Control of gray leaf spot on best treatment (Headline), but this was not statistically corn with fungicides in Ohio, 1996. F & N Tests 53:287. significant (Figure 4) (Jackson 2006). Lipps, P.E., and A.L. Johnston. 1999, Control of gray leaf spot on hybrid corn with fungicides in Ohio, 1998. F & N Tests Application Timing 54:352-353.
The most common timing for single applications is at Munkvold, G.P., and X.B. Yang. 1995. Crop damage and epi silking, although earlier applications can be effective if demics associated with 1993 floods in Iowa. Plant Disease disease is developing heavily prior to silking. Second appli 79:95-101. cations are usually made 2 weeks after the first application, Munkvold, G.P., C. A. Martinson, J.M. Shriver, and P.M, Dixon. although intervals of up to 3 weeks can be used with the 2001. Probabilities for profitable fungicide use against gray current fungicides. A common question is,“How late can leaf spot in hybrid maize. Phytopathology 91:477-484. I start making applications and still have an economic impact on disease?” This question arises when the disease Paul, P. A., and G.P. Munkvold. 2004. A model-based approach does not develop or is not noticed until some time after to preplanting risk assessment for gray leaf spot of maize. silking. Although there are no definitive data, a rule of Phytopathology 94:1350-1357. thumb is that a first application made more than 2 to 3 Paul, P.A., and G.P. Munkvold. 2005. Regression and artificial weeks after silking has little chance of being profitable. neural network modeling for the prediction of gray leaf spot The potential for a fungicide to protect yield is limited of maize. Phytopathology 95:388-396. to how much grain filling remains to occur between the Pedigo, L.P, 1999. Entomology and Pest Management Prentice fungicide application and physiological maturity. As Hall, Upper Saddle River, NJ. 691 pp. the plant nears maturity, the potential to protect yield diminishes, regardless of disease pressure. Shaner, G., and G. Buechley. 1999. Effect of fungicides on gray leaf spot, 1998. F & N Tests 54:354.
Summary Stromberg, E.L., and L.E. Flinchum. 1998. Evaluation of foliar Fungicides can be used profitably to control foliar diseases fungicides for the control of gray leaf spot disease on corn in on hybrid corn, but, typically, the practice is profitable Virginia, 1997.F & N Tests 53:143-144. only when a susceptible hybrid is grown and conditions Stromberg, E.L., and L.E. Flinchum. 1999. Evaluation of foliar are very favorable for disease. Several risk factors should fungicides for the control of gray leaf spot of corn in Virginia, be taken into consideration in making fungicide appli 1998. F & N Tests 54:359-360. cation decisions on hybrid corn. Decision-aid tools are Stromberg, E.L., and L.E. Flinchum. 2002. Evaluation of foliar being developed to help quantify the risk of yield loss fungicides for the control of gray leaf spot of corn in Virginia, and assist in making effective decisions. If applications 2001. F & N Tests 57:FC91. of strobilurin fungicides have effects on corn yields independent of disease control, these effects must be Stromberg, E.L., and L.E. Flinchum. 2003. Evaluation of foliar measured so that they can be considered quantitatively fungicides for the control of gray leaf spot of corn in Virginia, in the cost/benefit estimation that should be the basis 2002. F & N Tests 58:FC002. of fungicide application decisions. Stromberg, E.L., and C.C. Kenley. 2005. Evaluation of foliar fungicides for the control of gray leaf spot of corn in Virginia, References 2004. F & N Tests 60:FC074.
Gorman, D,, B.M. Anderson, and L. Abad. 1997. Yield loss of Stromberg, E.L., and C.C. Kenley. 2006. Evaluation of foliar corn hybrids with differing levels of gray leaf spot resistance, fungicides for the control of gray leaf spot of corn in Virginia, pp. 171-182. In Proceedings of the 52nd Annual Corn and 2005. F & N Tests 61:FC061. Sorghum Research Conference, Chicago, IL, December 10-11,1997, Ward, J.M.J., M.D. Laing, and F.H.J. Rijkenberg. 1997, Frequency and timing of fungicide applications for the control of gray Jackson, T. A. 2006. Evaluation of foliar fungicides on gray leaf leaf spot in maize. Plant Disease 81:41-48. spot of corn in Nebraska, 2005. F & N Tests 61:FC041. Ward, J.M.J., E.L, Stromberg, D.C. Nowell, and F.W. Nutter, Jr. Jenco, J.H. 1995. Epidemiology of Cercospora zeae-maydis on Zea 1999. Gray leaf spot: A disease of global importance in maize mays in Iowa. M.S, thesis, Iowa State University. 69 pp. production. Plant Disease 83:884-895.
2007 Illinois Crop Protection Technology Conference ♦ 33 Application Strategies to
Improve Crop Health ■ I
i i i i ■' Robert E. Wolf
challenging aspect of combating crop disease coverage into the lower parts of the canopy. Adding an is the lack of practical experience in making electrostatic charge to the spray does not provide signifi fungicide applications into dense crop canopies cant improvement. suchA as soybeans during the growth stages during which The following sections provide a brief review of the a disease such as Asian soybean rust may strike. Experi various studies, ence with disease control in heavy canopies indicates that getting the spray droplets to penetrate into the canopy Field-Canopy Penetration Trials would be beneficial in achieving the best coverage and in improving efficacy. However, experience also tells us Conventional Sprayer in Soybeans that when using conventional spray systems, it can be Trials were conducted using a conventional field sprayer very difficult to achieve adequate coverage into lower equipped with turbo flat fan and venturi flat fan nozzles, parts of heavy crop canopies. each sprayed at 5,7.5,10, and 12,5 gallons per acre (GPA). This article reviews the results of multiple studies under Comparisons were evaluated between nozzle types and taken to gain insight into achieving better in-canopy among application volumes. When comparing nozzle deposition of crop protection fungicides. Field and labo type in the bottom of the canopy, findings show that ratory experiments were conducted using conventional, the turbo flat fan had slightly better coverage at 5 and electrostatic, and aerial application systems, comparing 10 GPA, while the venturi nozzle had more coverage at each to achieve this purpose. For each system, typical 7.5 and 12.5 GPA. W ith the turbo flat fan, coverage in spray operation parameters were used as treatments, the bottom of the canopy improved as GPA increased while comparing nozzle types, application volumes, and from 5 to 12.5. This trend was not apparent with the deposition aid products. For all trials, either water-sen venturi nozzle. With both nozzle types, the most cov sitive papers or Kromekote paper was positioned near erage was found at 12.5 GPA. When the nozzle types the top, middle, and bottom of the canopy to collect the were averaged across all canopy locations (top, middle, spray droplets, and DropletScan was used to measure and bottom), only slight differences in nozzle type were and compare the coverage differences. measured, with just a slight edge shown in amount of coverage by the venturi nozzle. Differences in application The studies showed that, when using the evaluated volume were apparent, with improved coverage shown application systems, applicators will have limited success with each volume increase. in placing droplets into the lower parts of full-canopied soybean plants. With the conventional spray system, Electrostatic Sprayer in Soybeans nozzle type had little effect but differences were measured. For the conventional and aerial trials, coverage improved Trials were conducted using a conventional sprayer with increased application volumes. The addition of equipped with an electrostatic spray system. Compari deposition aids tends to improve the total amount of sons were made between extended-range flat fan and
34 ♦ 2007 Illinois Crop Protection Technology Conference turbo flat fan nozzles with and without the electrostatic at 3 GPA, the combination treatments of Interlock and system turned on. Measurements were taken in three Preference and Interlock and Rivet were best, with the canopy locations. Differences in nozzle type were found Interlock and Preference showing the most coverage. in the top of the canopy with little difference measured When averaged across all coverage levels, the 3 GPA in the lower parts of the canopy. W ithout electrostatics, treatments were superior to the 1 GPA treatments, the turbo flat fan had significantly more coverage in the except for the Placement and Preference, Again, in all top of the canopy than the extended-range flat fan did. treatments averaged across the levels of coverage except However, with electrostatics, the extended-range flat for Placement and Preference at 3 GPA, the deposition- fan significantly outperformed the turbo flat- fan. W hen aid treatments were better than water and crop oil alone. comparing electrostatic on versus off in the bottom of the All deposition aids at 1 GPA exhibited better coverage canopy, small amounts of coverage were measured, with than water and crop oil. no differences measured with the extended range and a slight improvement in coverage for the turbo flat fan over Laboratory and Field Canopy Penetration the extended-range flat fan without electrostatics. No Trials— Nozzle Type in Soybeans differences were seen when comparing the nozzle types Laboratory and field trials were conducted to determine at the lower canopy level. If anything, a slight decrease in the effect of nozzle type on coverage in the bottom of a coverage was found with the turbo flat fan with electro soybean canopy. For the laboratory trial, potted soybean statics. W hen all levels of coverage were averaged across plants were arranged in a dense canopy representing a nozzle type, the extended-range flat fan had slightly more drilled soybean field. At the time of the laboratory trials, coverage with the electrostatics on. However, with the the soybean plants were 25 inches tall and in the growth turbo flat fan, more coverage was achieved without the stage R1 to R2, with an estimated canopy fill of 90% to electrostatics. W ithout electrostatics, the turbo flat fan 95%. The second trial was conducted in a soybean field. outperformed the extended range, but with electrostatics, In the latter case, the soybean plants were drilled and, the extended range outperformed the turbo flat fan. at the time of the treatments, were 18 inches tall and in the growth stage R3 to R4. The canopy was estimated Aerial Sprayer in Soybeans at 75% filled (Table 1). Field trials were conducted using an airplane to deter Nozzle types used in the laboratory study were selected mine the effect of increased application volume and the based on possible choices from selected nozzle manufac addition of a deposition aid on coverage in the lower turers, The field-trial nozzle choices were selected after parts of a soybean canopy. Volumes compared were 1 reviewing the results from previous trials conducted in the and 3 GPA with a combination of four deposition aids. laboratory. Several nozzles with poor performance were The deposition-aid treatments were Preference, Placement and Preference combined, Preference and Interlock TABLE i • Materials and methods for laboratory and field nozzle trials. combined, and Interlock and Rivet Laboratory treatments Field treatments combined. All comparisons included water and crop oil concentrates with a Target GPA1 20 GPA 20 GPA treatment of water and crop oil as the Application speed 10 mph 10 mph standard. In all comparisons except Boom height 20 inches 20 inches Placement and Preference, the 3 GPA application volume exhibited more Nozzle type 20 configurations 12 configurations lower canopy coverage when compared Spray solution Tap water and NIS Tap water, NIS, Headline to 1 GPA, All deposition-aid treatment Soybean plant height 25 inches 18 inches somewhat improved the coverage when compared to the water and crop oil treat Soybean growth stage R -R 2 R3-R4 ment. The exception was the treatment Soybean row spacing Pots arranged as drilled Drilled of Placement and Preference, in which Canopy condition 90%-95% filled 75% filled the 1 GPA treatment was significantly better than 3 GPA, In all comparisons XA11 applications were made with a spray track machine designed for this experiment.
2007 Illinois Crop Protection Technology Conference ♦ 35 eliminated for the second trail. Treatments were designed The spray material used in the laboratory study consisted to compare all the nozzle types at 20 GPA and 10 mph. of a mixture of 500 mL (0.5 quart) of tap water and The orifice size chosen was selected first to meet the flow non-ionic surfactant (NIS) at 5% volume/volume. For rate requirements for the GPA and mph (0.67gallons/ the field trial, Headline (fungicide), to simulate an actual minute) and then for the pressure necessary to qualify for tank mix, was also added. the droplet spectra desired. The droplet spectrum of 200 A special spray track machine was designed and fabricated to 300 VM D microns was selected for these studies, and to simulate actual field spraying conditions and to facili most all nozzle treatments were selected to fit this range. tate multiple treatments and replications. The spray track This range matches the American Society of Agricultural had an aluminum bar 24 feet long, with an electric motor and Biological Engineers’ (ASABE) Droplet Standard and chain-driven sprayer boom. The electric motor was S-572 classification as high-fine to mid-medium-sized equipped with three gears that drive a chain that propelled droplets. Nozzle manufacturers’ droplet sizing charts were the sprayer boom on the aluminum bar at 5, 10, and 15 used to fit the nozzles for this study (Table 2). mph. The electric motor was equipped with a brake to
TABLE 2 • Treatment, nozzle, pressure, droplet spectra classification, and tank mix solution.
Droplet spectra Treatment Lab nozzle treatments1 Field nozzle treatments2 psi classification (DSC)3
1 X R 11006 X R 1 1 0 0 6 50 M ed iu m
2 T T 11006 T T 1 1 0 0 6 50 C oarse
3 T T 11005 T T 1 1 0 0 5 75 Coarse/medium
4 T T 11004 T T 1 1 0 0 4 95 M ed iu m
5 TD XR 11004 TD XR 11004 115 M ed iu m
6 T D T T 11004 TD TT 11004 115 M ed iu m
7 TD XL 11004 X 115 M ed iu m
8 S R 110-05 X 75 M ed iu m
9 S R 110-06 S R 110-06 50 Fine/medium
10 E R 8 0 -0 6 E R 8 0 -0 6 50 M ed iu m
11 TwinCap T T 110034 TwinCap TT034 50 M ed iu m
12 TwinCapTT 110044 X 27 M ed iu m
13 Twinjet 064 Twinjet 064 50 M ed iu m
14 TJ Duo T T 03, wide4 X 50 M ed iu m
15 TJ Duo T T 03, narrow4 TJ Duo TT03, narrow4 50 M ed iu m
16 Teejet Duo XR 034 X 50 M ed iu m
17 AirMix TF054 AirMix TF 054 75 M ed iu m
18 T D T F 0 4 4 X 115 M ed iu m
19 S R 1 1 0 -0 3 4 X 50 M ed iu m
20 MR 110-0254 X 75 M ed iu m
1 All treatments used a tank mix solution of tap water and non-ionic surfactant. 2 All treatments used a tank mix solution of tap watei non-ionic surfactant, and Headline. 3Based on the ASABE S-572 droplet spectra classification system and nozzle manufacturers’ charts/suggestions. 4Twin or double orifice nozzle configurations.
36 ♦ 2007 Illinois Crop Protection Technology Conference stop the spray boom at the end of track. The system was TABLE 4 • Field treatment means for percent area powered in the field by a field generator. The spray bar was coverage. supported in the field on tripods and could be adjusted Percent area to different heights. The whole setup could be moved to Treatment1 Nozzle coverage different locations in the field by sliding the tripod along 1 XR11006 8.1 ab3 the ground. The sprayer boom had two nozzles spaced at 20 inches that were controlled by a solenoid valve oper 2 TT11006 6.0 b ated by a battery-operated remote control. The pressure 3 TT11005 10.0 a for each treatment was created by using a C 0 2 cylinder. 4 T T 11004 8.5 ab All the treatment solutions were placed in 500 mL (0,5 quart), high-pressure spray bottles and attached to the 5 SR 11006 7.5 ab 6 ER 8006 9.0 ab 7 TD XR04 7.3 ab TABLE 3 • Laboratory treatment means foT percent area coverage. 8 TD TT04 7.9 ab 9 Twinjet 062 6.3 b Percent area Treatment1 Nozzle coverage 10 TJ Duo TT03, narrow2 6.4 b 1 XR 11006 1.9 cd3 11 AirMix TF 052 7.1 ab 2 T T 11006 5.1a 12 TwinCap TT032 6.7 ab 3 T T 11005 2.6 bed LSD 3.58
4 T T 11004 4.2 ab 3A11 treatments used a tank mix solution of tap water, non-ionic surfactant, and headline. 5 TD XR 11004 5.1a 2Twin or double orifice nozzle configurations. 6 T D T T 11004 3.5 abed 3Different letters indicate significance at P = 0.10. 7 TD XL 11004 3.4 abed 8 SR 110-05 3.5 abed spray boom to complete the trials. All treatments were 9 SR 110-06 3.9 abc randomly assigned, with two replications. 10 ER 80-06 4.3 ab The results for laboratory treatments indicated that 11 TwinCap T T 110032 2.7 bed percent area coverage (PAC) in the lower canopy ranged 12 TwinCap T T 110042 2.9 abed from 1.6% to 5,1%, with an LSD of 2.29%. The best coverage in the lower canopy was attained with the 13 Twinjet 062 3.5 abed TT11006 sprayed at 50 psi and the TD XR 11004 at 14 TJ Duo T T 11003, wide2 1.6 d 115 psi (5.1%). There was no significant difference in the 15 TJ Duo TT 11003, narrow2 3.4 abed top 15 nozzle treatments. The top four ranked nozzles for PAC were single nozzle orifice designs. The average 16 Teejet Duo XR 110032 2.4 bed PAC for the single nozzle treatments was greater than 17 AirMix TF052 3.7 abed the PAC for the double nozzle designs (3.75% to 3.11%). 18 T D T F 042 4.2 ab Three of the significantly lowest coverage amounts were from double orifice designs (Table 3). 19 SR110-032 3.1 abed 20 MR 110-0252 3.6 abed For the field treatments, PAC ranged from 6% to 10%, with an LSD of 3.58%. The best coverage in the lower LSD 2.29 canopy was attained with the T T 11005 sprayed at 1A11 treatments used a tank mix solution of tap water and non-ionic 75 psi (10.0%). The next closest coverage amount was surfactant. delivered by the ER 8006 at 50 psi (9.0%). The lowest 2Twin or double orifice nozzle configurations. three nozzles, the TJ Duo T T 11003/narrow angle at 3Different letters indicate significance at P = 0.10. 50 psi (6.7%), Twinjet 11006 at 50 psi (6,3%), and the
2007 Illinois Crop Protection Technology Conference ♦ 37 T T 11006 at 50 psi (6.0%) were all significantly less not supported by the data in these studies. Therefore, it than the TT 11005, but not any of the other nozzle may not be necessary to outfit spray systems with nozzles treatments (Table 4). other than the conventional turbo and extended-range types. These conventional nozzle systems performed As shown in previous research, canopy density is a major well, provided that smaller orifice sizes and higher pres factor in controlling the amount of penetration into the sures were selected. The data show that, in addition to lower portions. In both studies, the single nozzle designs, calibrating for the increased GPA recommendations for on average, placed more coverage into the bottom of the fungicide applications, an additional step to calibrate canopy when compared to the double nozzle designs. for the proper droplet spectra classification is essential. The double nozzles were expected to provide better lower This extra calibration step is not a common practice but, canopy coverage. Another interesting finding was that when taken, typically results in a smaller orifice used at a the venturi designs at higher pressures did not perform higher pressure. For example, in this study, theT T 11006 nearly as well as the conventional nozzles at the lower at 50 psi, the TT 11005 at 75 psi, and the T T 11004 pressures. at 95 psi all provided the same application volume but a Even though differences were minimal for most treat different droplet spectra, resulting in different amounts ments, the strategy to use twin or double nozzle con of coverage in the lower canopy. figurations for improved lower canopy penetration is
38 ♦ 2007 Illinois Crop Protection Technology Conference Tillage System Effects on Root Growth and Fertilizer Placement Considerations R.M . Cruse
he environment surrounding plant roots is Conservation tillage systems tend to create a more non extremely complex and variable. For example, it uniform soil environment than that which occurs with is not uncommon for the surface 1 to 2 inches of conventional tillage systems. This nonuniform condition T soil to be very dry while very wet conditions exist at deepermay affect total root growth and root growth patterns. In areas within the root zone. Surface soil temperatures may general, total root growth in a nonuniform soil environ differ by 20°F or more from that observed at deeper layers ment will be similar to that occurring in a uniform one. within the rooting zone. A zone of compactions caused However, plants tend to grow a disproportionate amount by wheel traffic may create very different conditions on of root mass in the most favorable portion of the rooting one side of a crop row compared to the other side where zone, reducing the quantity of roots in the zone least no traffic occurs. The environmental variations occurring favorable for growth (Russell 1977). This evolved survival in the root zone tend to be much greater than those that mechanism is called root growth compensation. occur above ground. Tillage, Root Growth, and Fertilization To most effectively understand crop response to fertility practices, we should understand how crop root systems Two tillage systems that have the potential to create the respond to the soil environmental conditions. This is most nonuniform soil environmental conditions are ridge particularly true with conservation tillage systems, because tillage and no-till. By design, the ridge system results in we tend to create more soil environmental variability a warm row area and cool interrow area. W heel traffic is with conservation tillage than we do with conventional ideally confined to the interrow area, creating a compacted tillage systems. area to one side of the row and likely an untrafhcked area to the opposite side. The ridge will be drier than Tillage and the Soil Environment the interrow area. The most favorable root growth zone is in and below the ridge and in the interrow zone not Conservation tillage creates a different soil environment compacted by wheel traffic. Fertilizer applications should than that which commonly occurs with conventional be directed to the zones favoring root growth. Applica tillage systems that use full-width soil disturbance and tions in the cool, wet interrow zone subjected to wheel burial of surface plant residue. Because of surface plant traffic will likely be less efficiently used than applications residue, soil temperatures tend to remain cooler during to preferred root growth zones. the spring warm-up. Soil water contents tend to be higher, particularly near the soil surface. Depending on traffic No-till management has the potential to create spatial patterns and tillage tools used, compaction patterns may variations similar to those occurring for ridge tillage, be more prevalent. W ith less soil mixing, fertilizer-applied depending on how surface plant residue is managed. nutrients tend to become more concentrated in the zone Clearing residue from the row zone creates a relatively of application. warm and dry zone in the row compared to zones under the residue. This management practice favors rapid early
2007 Illinois Crop Protection Technology Conference ♦ 39 plant growth and root growth in the row zone area. If Developing bands of fertility within a field seems to be a plant residue remains spread uniformly on the soil surface, favorable practice for soils with low fertility, particularly horizontal root growth patterns will be similar to those when application rates are not excessive. Barber (1984) occurring with conventional tillage, except root growth indicates that fertilizer should be concentrated in roughly tends to be shallower, No-till conditions keep the surface one third of the soil volume for maximum uptake effi soil moist for a longer period of time than conventional ciency. If application rates are high, or high soil test levels tillage conditions and, as a result, root growth can and exist, placement seems to have little effect. While one does occur to a greater extent near the soil surface. subsurface band application will not result in one third of the soil volume being fertilized, repeated applications will Conservation tillage practices that use a tool such as a likely result in nutrient concentration zones considerably disk or chisel plow create more uniform conditions than larger than those of a single application (this assumes do ridging or no-till practices. Wheel tracks tend to be that the tractor driver and applicator do not perfectly removed, at least near the surface, to a significant extent. match the previous years application—an assumption Plant root growth as affected by soil temperature and normally valid for typical application). water conditions is similar to root growth occurring with conventional tillage. An additional advantage of fertilizer banding is in weed control. Weeds, similar to crop plants, respond to fertility. As tillage intensity decreases, fertility uniformity in Subsurface banded fertilizer near the plant row in a zone the field also tends to decrease. Moldboard plowing, to favorable for crop root growth favors nutrient uptake by exemplify, followed by secondary tillage operations mix the crop as opposed to nutrient uptake by weeds growing fertilizer-applied nutrients quite thoroughly throughout randomly in the field. High fertility conditions near the the plow layer. Less intensive primary tillage operations, soil surface spread uniformly across the field seem to such as chiseling or disking, result in horizontally uniform favor rapid early weed growth in that many weed species distributions of broadcast fertilizers. However, nutrients germinate and grow from a shallow soil depth. tend to concentrate near the soil surface more than that which occurs with more intensive tillage operations. Fertility Placement Recommendations W ith ridge tillage or no-till, fertility tends to build in the zone of application. Banding results in zones of high Consider zones that may be either favorable or unfavorable fertility, assuming for root growth when deciding on fertilizer placement options. If potentially unfavorable zones exist, avoid ♦ the row positions are reasonably fixed with time; placement in these zones. and If you use no-till or ridge tillage for row crop production ♦ applications are directed to the same position annu and soil test levels are not high, attempt to place fertilizer ally. consistently in the same position. Banding may be prefer Surface broadcast applications tend to result in surface- able to broadcast applications. If tillage is more uniform layer fertility increases, with fertility decreases in deeper across the field and/or if soil test levels are high, placement layers. is less important. If small grains and/or forage crops are part of your rotation, fertilizer placement practices other Nutrient concentration zones affect root growth. Phos than banding may be preferable. phate and nitrate stimulate root growth in the zones of nutrient enrichment. Potassium does not. Thus, fertil References izer concentrations near the surface tend to stimulate root growth in this zone, assuming soil moisture and Barber, S.A. 1984. Soil Nutrient Bioavailability. John Wiley & temperature conditions are favorable. Banding fertilizers Sons, New York. containing phosphate or nitrogen will likely encourage Russell, R. S. 1977. Plant Root Systems. Their Function and Inter root proliferation in the application zone if the tillage action with the Soil. McGraw-Hill, London. system does not disturb the band and if soil fertility test levels are not high or very high. The enhanced root growth resulting from nutrient concentration favors plant survival and production.
40 ♦ 2007 Illinois Crop Protection Technology Conference Why Is My Field Showing Potassium Deficiency?
Fabian G. Fernandez
Importance of Potassium in the Plant quality, and improving overall plant development and yield (Marschner 1995). All these physiological aspects, fter carbon, hydrogen, oxygen, and nitrogen, linked in varying degrees to K, make this nutrient a key potassium (K) is the most abundant element in element for sound agricultural management of intensive most crops (Rosolem et ah 1993; Mullins and cropping systems. BurmesterA 1999). Generally, optimal plant tissue K is in the range of 2% to 5% based on plant dry weight (Darst Understanding K in the Soil and Wallingford 1985). In addition, throughout the entire life cycle of most plants, this nutrient plays an important Potassium is the seventh most abundant element in the role in many physiological plant functions. Under severe earths crust (Sparks and Huang 1985). Because most K is K deficiency, lignification of vascular bundles is reduced, bound in the mineral form of K-feldspars and micas and contributing to the high susceptibility to lodging (Marsch- some is fixed (also known as nonexchangeable or slowly ner 1995). Water-use efficiency under drought conditions available K) in interlayer regions of clays, only about 2% is enhanced by the role of K in stomatal regulation and of the total K is in the exchangeable and solution phases maintenance of turgor pressure in the vacuole. Potas (Sparks 1987). In most soils, adequate K supply to a sium has been classified as the principal inorganic solute growing crop normally requires addition of this nutrient having a key role in osmoregulation (Hsiao and Lauchli in the form of fertilizer. However, applied K can quickly 1986). For cell extension to occur, cell wall extensibility become unavailable to plants by being fixed between has to increase and solute accumulation must take place clay lattices or, in coarse texture or low cation exchange to maintain osmotic potential. Cell extension—plant capacity (CEC) soils, it can be leached out of the root growth—is partially regulated by K associated with zone. It also can be lost by soil erosion (Figure 1). Part inorganic and organic acid ions (Green and Muir 1979; of the applied K will remain available to the plant, but Mengel and Arneke 1982). The driving force of K influx assessing K availability is difficult because soil-phase K+ in localized parts of the plant allows for the mechanical (the pool from which plants obtain K) exists in a dynamic reorientation of leaves in response to light signals. This equilibrium with the other K pools, and soil and plant phototropic response renders plants the ability to either characteristics influence how much, where, and when K increase light interception to maximize photosynthesis will be available or taken up. or to avoid excess light to protect against injury caused by high light intensity (Koller 1990). In addition, K First, Some Tilings About Soil Sampling is important in regulating more than 60 enzymes that forK catalyze a great number of metabolic activities (Suelter The goal in collecting soil samples is to characterize the 1970, 1985). Potassium is important in maintaining nutrient status of the soil. This does not mean that the charge balance by counterbalancing the negatively soil test value should be viewed as an absolute value or charged ions present in the cytoplasm, increasing disease that individual samples should necessarily yield the same resistance, controlling phloem transport, increasing crop
2007 Illinois Crop Protection Technology Conference ♦ 41 Plant Uptake Factors to Consider When, despite our best efforts to “follow the book,” we see K deficiencies in our fields, it is natural to think, “W hat did I do wrong?” o r“The lab is not doing their job right.” Let us suppose that no one is to be blame (i.e., your K soil test levels are at an optimum). Then why is the crop showing potassium deficiency? Potassium availability for a crop is regulated by many factors, and the observed deficiency in the plant could be simply the indicator that some of those factors are not allowing the crop to take up all the K it needs. A discussion of some of the major factors involved in regulating K availability follows.
FIGURE i • The potassium cycle, showing components, Water Availability inputs, and losses. Potassium reaches the root surface of a crop in three main ways: (1) diffusion: ions moving along a concentra tion gradient from high to low concentration points, (2) test result, but rather that, through sampling, we captured mass flow: ions being carried to the root in the convective the variability present in the field. However, the results flow of soil water originated by plant transpiration, and from a soil test cannot be more accurate than the accuracy (3) root interception: ions are encountered by the roots of the sample obtained to characterize a field. For this as they grow into the soil. O f these three, diffusion is reason, soil sampling must be viewed as a crucial part of by far the most important mechanism of K acquisition soil testing and must be done carefully. (Table 1). Unfortunately, the greatest source of inaccuracy in a soil In order for K+ ions to diffuse, there has to be water test value is typically associated with the technique used present in a continuum from the root surface to where to collect the sample. Prior to widespread use of fertilizers, the ion is present. When soils dry, pore spaces become it was relatively easy to find homogeneous levels within void of water and air fills the space. This reduces diffu a field. W ith the adoption of fertilization, and especially sion by lowering the cross-sectional area for diffusion and where nutrients are band applied, large differences in test increasing the tortuosity (or length) of the diffusion path. results can be found within a given field. Because K is Although K is present in the soil under these conditions, mostly an immobile nutrient, under reduced soil mixing this nutrient could become positionally unavailable to by tillage, it becomes vertically and horizontally strati fied in the soil. Therefore, to adequately capture K variability in a field, the TABLE i • Relative significance of root interception, mass flow, and diffusion in supplying corn with its nutrient requirements from a fertile Alfisol silt loam area should be divided by (amounts are given in lb/A). major units that differ in Approximate amount supplied by soil type, topography, past Amount needed and present management, Nutrient for 150 bu/A Root interception Mass flow Diffusion and any other major dif Nitrogen 170 2 134 34 ference. Depth of sam Phosphorous 36 1 2 33 pling, adequate sampling rate, time of year for the Potassium 174 4 31 139 sampling, and the type of Calcium 36 54 134 0 crop to be planted should Magnesium 40 13 89 0 also be considered care fully when designing a soil Sulfur 20 1 58 0 sampling strategy. Adapted from Barber 1995.
4 2 ♦ 2007 Illinois Crop Protection Technology Conference the crop (Barber 1995). The need for adequate supply scenario, root growth may be more vigorous in deeper of water to take up K was demonstrated in a greenhouse portions of the soil profile if water availability is greater. study in which soybean (Glycine max (L.) Merr.) was However, strong vertical stratification of nutrients with grown under two K treatments: K" and K+ (80 and 164 greater concentrations in the surface layer means that the ppm K, respectively), and two watering regimes: W~ and deeper roots might not encounter sufficient K to supply W + (soil was allowed to dry to 55% field capacity (FC) plant needs. Fortunately, in most years, droughty condi before rewatering to 85% FC, and soil water content was tions do not extend for a prolonged period of time, and, maintained constant at 85% to 95% FC, respectively). once rainfall replenishes water in the K-rich surface layer Accumulation of K in the shoot was significandy increased of the soil, K deficiencies tend to disappear. only when sufficient water was available to take advantage of the added fertility (Figure 2) (Fernandez 2006). W hen Oxygen Levels in the Soil K was supplied without adequate water availability, the An opposite problem to drought, but with similar impact crop showed similar tissue K concentrations as those on K acquisition, occurs when soils become saturated grown under a low K testing soil. with water. As air in the soil pores is displaced by water, Adequate soil water content is not needed just for K gas exchange with the atmosphere is reduced about 104 diffusion. Potassium uptake is an active process; under times (due to lower diffusion rate of gas in water, compared reduced soil water availability, root activity and growth will to air), and oxygen levels in the soil are depleted quickly decline and hinder K uptake. During prolonged periods by respiring roots and soil fauna (Marschner 1995). of drought, K deficiencies are often seen more frequently Under these conditions, root growth and activity decline. in no-tillage or reduced tillage fields. In these tillage Because K uptake is an active process, low oxygen causes systems, due to little mixing of surface-applied fertilizers a reduction in K acquisition. In fact, soil aeration has a into the soil, K and other nutrients tend to concentrate more pronounced impact on K uptake than on other ions. mostly in the surface layer of the soil. This layer may be Danielson and Russell (1957) showed relative uptake more susceptible to drying under prolonged droughty of 86Rb (a counterpart for K) declines rapidly when soil conditions compared to deeper layers of the soil. In this oxygen levels dropped below 10%.
Soil Temperature Potassium uptake involves biological, chemical, and physical reactions. Most of these reactions require a certain temperature to provide sufficient kinetic energy to move the reaction forward. W hen cool soil conditions are present, it is more common to see K deficiency than when the crop is growing in warm soils. This is especially true for reduced tillage and no-tillage systems in which large quantities of crop residue left in the surface of the soil delay warm-up by reducing direct solar radiation on the soil. Low temperature can impact K uptake by reducing the ability of either the root to absorb K or of the soil to supply K to the root (Ching and Barber 1979). FIGURE 2 • Mean vegetative tissue K content of The ability of the root to absorb K in cool soil is reduced individual soybean plants grown in a greenhouse pot- due to a decline in both root growth and activity. Soil K study. supply is also reduced under low temperatures because diffusion rates to the root and the actual rate of release of K~ and K+ represent soil K treatments with starting soil test K concentrations equal to 80 and 164 ppm K, respectively. W - and exchangeable K into the soil solution are slowed down. W + refer to insufficient water treatment in which soil dried to 55% field capacity (FC) before being rewatered to 85% FC and Crop sufficient water treatment in which soil water was maintained It is important to consider the amount, rate, and time between 85% and 95% FC, respectively. Bars with same letters are not significantly different (P < 0.05). of K uptake for different crops. For instance, K uptake
2007 Illinois Crop Protection Technology Conference ♦ 43 by corn (Zea mays (L.)) occurs rapidly between V6 and Danielson, R.E., and M.B. Russell. 1957. Ion absorption by corn V12 and very rapidly from V12 to V18 development roots as influenced by moisture and aeration. Soil Science Society stages. Normally, by the middle to the end of July, this of America Proceedings 21:3-6. crop has taken up 100% of its K. Because of this uptake Darst, B.C., and G.W. Wallingford. 1985. Interrelationship of pattern, it is more common to see temporary K deficiency potassium with cultural and management practices, pp. 559 symptoms in corn in the early season, often in relation 573. In Munson, R.D. (ed). Potassium in Agriculture. ASA, to cool and wet soil conditions. On the other hand, CSSA, and SSSA, Madison, WI. soybeans take up K over a prolonged period of time, Fernandez, F.G. 2006, Potassium acquisition by soybean affected with greater rates during the latter part of the growing by stratified soil potassium, growth stage, and soil water season as the crop enters the reproductive (R) stages content. Ph.D. dissertation, Purdue University. of development. Typically, soybeans will have taken up 100% of their K sometime during the end of August to Green, J.F., and R.M. Muir. 1979. Analysis of the role of potas middle of September. sium in the growth effects of cytokinin, light and abscisic acid on cotyledon expansion. Physiologia Plantarum 46:19-24. Other important crop characteristics that can influence crop K uptake include the size of the root system and its Hsiao, T.C., and A. Lauchli. 1986. Role of potassium in architecture. Nutrient and water uptake are root surface plant-water relations, pp. 281-312. In Tinker, B., and A. area phenomena. Thus, increasing root surface area will Lauchli (eds). Advances in Plant Nutrition, Volume 2. Praeger increase K uptake. The architecture of the root can have Scientific, New York. important implications regarding the portion of the soil Koller, D. 1990, Light-driven leaf movements. Plant, Cell, and profile that will be exploited and the degree of competi Environment 13:615-632. tion between neighboring roots. Fibrous-rooted crops Marschner, H. 1995. Mineral Nutrition of Higher Plants, 2nd such as corn and wheat (Triticum aestivum (L.)) are more edition. Academic Press, San Diego. capable of exploiting the surface layer of the soil profile compared to tap-rooted crops such as soybeans. Mengel, K., and W.W. Arneke. 1982. Effect of potassium on the water potential, the osmotic potential, and cell elonga Finally, plant and root age, K influx characteristics of tion in leaves of Phaseolus vulgaris. Physiologia Plantarum plant roots, and root exchange capacity differences are 54:402-408. other crop parameters that can have important impacts on K uptake. Mullins, G., and C. Burmester. 1999. Potassium uptake by crops during the season, pp. 123—132. In Oosterhuis, D.M., and Other Factors G.A. Berkowitz (ed). Frontiers in Potassium Nutrition: New Perspectives on the Effects of Potassium on Crop Plant Physiol- Any other factors that influence K availability in the soil ogy. Potash and Phosphate Institute/Potash and Phosphate or the ability of the root to take up this nutrient can result Institute of Canada, Norcross, GA. in K deficiencies showing up in fields testing at optimal Rosolem, C. A,, M. A. Bessa, and H.F.M. Pereira, 1993. Potassium K levels. A few of these factors are soil mineralogy and dynamics in the soil and K nutrition of soybeans. Brazilian the K-supplying power of the soil, which can reduce Journal of Agricultural Research 28:1045-1054. fertilizer use efficiency; soil acidity, which can impact both nutrient availability and root activity; pathogens Sparks, D.L. 1987. Potassium dynamics in soils, pp. 1—61. and pests that attack the root system or reduce crop In Stewart, B.A. (ed). Advances in Soil Science, Volume 6. efficiency; and soil compaction, which causes mechanical Springer-Verlag, New York. impedance for root penetration. Sparks, D.L., and P.M. Huang. 1985. Physical chemistry of soil potassium, pp. 201-276. In Munson, R.D. (ed). Potassium in References Agriculture. ASA, CSSA, and SSSA, Madison, WI,
Barber, S.A. 1995. Soil Nutrient Bioavailability: A Mechanistic Suelter, C.H. 1970. Enzyme activated by monovalent cations. Approach, 2nd edition. John Wiley 8C Sons, New York. Science 168:789-795.
Ching, P.C., and S.A. Barber. 1979. Evaluation of temperature Suelter, C.H. 1985. Role of potassium in enzyme catalysis, pp. effects on K uptake by corn. Agronomy Journal 71:1040— 337-349. In Munson, R.D. (ed). Potassium in Agriculture. 1044. ASA, CSS A, and SSSA, Madison, W I.
4 4 ♦ 2007 Illinois Crop Protection Technology Conference The Perfect Corn Stand
Emerson D. Nafziger ■ B P
efore we talk about how to get a “perfect" stand 1 shows, as an example, the population responses from of corn, it helps to know what stand, in terms of several Illinois locations in 2006. Such a range of responses Bplant numbers, we are trying to establish* This is fairly typical, with yield continuing to increase up number has been a moving target for corn in Illinois, but to 40,000 plants per acre under very good conditions mostly, and appropriately, the direction of that move (DeKalb and Urbana), to top out in the mid-30,000s ment is up. The average plant stand recorded in Illinois and sometimes drop off at higher populations under by the Agricultural Statistics Reporting Service in 2006 occasionally dry conditions (Monmouth), and to remain was 28,000 plants per acre, the same as in 2005 but up relatively flat over a wide range under very dry conditions about 10% since 2002 (NASS). Many producers have (Perry). In general, then, though there is a risk of losing increased their targeted plant population in corn in recent seed costs and even some yield when conditions are poor, years yet still wonder, after a year with good weather and there seems to be little risk, and some reward, in raising good yields, whether they should have set the planter for plant populations into the mid-30,000s in productive higher populations than they did. soils in Illinois. We have come to expect that yield response to plant One of the longest-running debates in corn production population will vary depending on conditions. Figure has been about the effect of uneven plant spacing on corn yields. This debate began in the 1980s, when Bob Nielsen at Purdue University started some innovative work in which he created very uneven stands and found that it reduced yields. He chose to measure plant spacing variability using the statistic “standard deviation” (SD), which increases from zero with a perfect stand to as much as 6 to 8 inches when stands are very uneven—for example, when many of the plants are present as doubles (two plants very close together) or there are many skips (missing plants) down the row. Measuring the SD requires measuring the spaces between individual plants; therefore, it is not a quick and easy measurement. In one of our early studies done by cooperating farmers in field-scale strips in Illinois, we found that faster plant FIGURE i • Corn plant population responses at ing speeds increased plant spacing variability slightly but four Illinois locations, 2006. The same corn hybrid had no effect on yield (Table 1). Others have reported (Pioneer* 34A18) was used at each location. SD values ranging from 2 to more than 4 inches, and,
2007 Illinois Crop Protection Technology Conference ♦ 45 TABLE i • Effect of planting speed on plant spacing and yield, averaged over on-farm trials in Illinois, 1996-1998.
Standard Plant Yield Planting deviation population (bushels speed, mph (inches) (per acre) per acre) 3 2.87 27231 152.5 5 2.99 27373 152.2 7 3.22 26996 153.1
LSD 0.05 0.33 NS NS Planting depth, in.
FIGURE 3 • Planting depth effect on corn yield, in a few cases, SD values as high as 6 to 8 inches have averaged over 3 years at Urbana, Illinois. been reported. Because SD values are influenced by plant population (and vice versa), SD values above 4 or plant spacing present in most fields. Modern planters 5 inches are almost always associated with low stands, do a very good job of seed distribution and placement, with a lot of missing plants. Exceptions might be when a which has led to a reduction in the problem of uneven serious planting malfunction occurs, with a large number spacing, though mistakes are still possible. As a general of doubles and skips, even at a high population. rule, spending money to try to improve a stand that is In a more recent study, we found that thinning plants less than perfect but within an acceptable range probably to an even stand compared to an uneven stand had will not increase profits much, if any. little effect on yield (Figure 2). After a number of such In many fields, uniformity of emergence and plant size investigations, most agronomists now believe that, while early in the season probably reduce yields more than does perfectly spaced plants down the row is the ideal, there nonuniformity of plant spacing. Planting depth is one is likely to be little yield loss under the small amount of factor that affects uniformity of emergence. The ideal variability (SD values less than 3 inches or so) in the depth may vary some depending on soil conditions, but, in most cases, planting 1.5 to 1.75 inches deep is likely to provide the best results (Figure 3). Both deeper and shallower planting tend to place seed in less-uniform conditions, which can contribute to unevenness in emer gence time or stand loss. If planting is done under reasonably good conditions, emergence in a field should normally take place over a period of less than 48 hours. We used a corn seed coating that both delayed and prolonged emergence, and found that yield decreased as a result (Table 2). It was not possible to separate the effects of emergence timing and uniformity in this study, but other evidence exists Final plant population, 000s that nonuniform emergence results in plants that are not uniform in size and that this nonuniformity can result FIGURE 2 • Effect of uniformly or randomly thinned in yield loss. Such yield loss probably occurs when late- plants on plant population response, UTbana, developing plants undergo more intense competition 2006. Standard deviation values (inches) w e T e 3.47 from adjoining (larger) plants, and therefore lose more (uniform, U) and 7.35 (random, R) at 18,000, 2.43 (U) and 4.42 (R) at 24,000,2.44 (U) and 3.57 (R) at 30,000, yield than the earlier-emerging, larger plants on either and 2.45 inches at 36,000. side can compensate for.
46 ♦ 2007 Illinois Crop Protection Technology Conference TABLE 2 • Effect of seed coating on timing and uniformity of emergence and companies compete to develop and on grain yield, Urbana, 1999. deliver seed with genetic ability to emerge well under a range of con Duration Yield Stand Days to 90% of emergence (bushels (plants per ditions, with good uniformity and Seed emergence (days) per acre) acre) protection against soil pathogens and insects. Equipment companies Untreated 7 2 208.7 33,189 have worked to produce planters Vi coated 17 17 185.7 33,686 better able to place seed at uniform Coated 20 11 176.4 32,110 depth and to distribute seed uni formly, and producers take care to LSD 0,05 20.1 NS ensure that planting takes place under good soil conditions. There is some room for improvement in The ability of seed to emerge quickly and uniformly is all of these areas, of course, but plant stand has dimin another factor that could affect emergence and yield. ished as a problem in Illinois, even as planting has moved While assertions have been made that certain seed grades earlier— and thus into soils that are colder on average. or seed lots might have problems with emergence, such problems are rarely seen. Over two years and two locations TABLE 3 • Corn yield from different seed grades. Data in Illinois, different seed grades have performed almost aTe averages oveT two Illinois locations (DeKalb and equally well (Table 3). Thus, we have little basis for using Urbana) and two years (2005 and 2006). seed grade as a performance factor. Some planters may distribute certain seed sizes or grades better than others, Seed grade Yield (bushels per acre) but its unlikely that, once in the ground, seed differs in Small flat 184.7 performance according to size. Medium flat 185.5 In summary, seed placement both horizontally and Large flat 190.1 vertically, into a soil environment that provides good seed-soil contact, a good rooting medium, and adequate Small round 188.7 plant nutrients and water is vitally important in produc Medium round 188.2 ing top corn yields. There is little to suggest that a large Large round 186.7 margin for improvement exists in this area, however. Seed
2007 Illinois Crop Protection Technology Conference ♦ 47 Fitting Wheat into Illinois Cropping Systems 1
Emerson D. Nafziger ffiili#*
ver the past 50 years, winter wheat has gone and wheat, respectively. The correlations between corn from being a major part of the Illinois cropping and wheat yields and between corn and soybean yields landscape to being a “minor” crop in the state, over this period are higher (R2 of about 0.25 for both) losingO out to corn and soybeans, which today occupy than the correlation between wheat and soybean yields some 21 million acres, compared to less than 1 million (R2 = 0.08). This difference likely reflects the fact that acres for wheat. Yields of the three crops have shown wheat responds very well to dry weather early in the a considerable amount of variability over recent years season (May and June), soybeans respond well to rainfall (Figure 1), and the coefficient of variability (CV) for after midseason, and corn responds favorably to both of wheat yield over the 11 years from 1996 through 2006 these factors. is higher (15%) than those for corn (11%) or soybeans In economic terms, however, with yields averaging less (9%). This relatively high yield variability, along with than 40% of corn and only about 30% more than soybeans, wheat quality and price volatility, accounts for some of and with prices usually not much higher than those for the decline in wheat acreage in recent years. corn, wheat hasn't competed particularly well with corn A related factor that has affected wheat acreage and pros and soybeans. There are, however, several reasons why we pects in Illinois is how the crop has fared in the “competi continue to grow wheat in Illinois. One is the chance to tion” with corn and soybeans for space in Illinois fields. doublecrop with soybeans, thus getting two crops from Over the past 11 years, average yields of these three crops the same field in one year, in the southern half of the in Illinois have been 149,44, and 57 for corn, soybeans, state. Doublecropping has little effect on wheat yield, and yields of doublecropped soybeans are variable, but under very good late-summer rainfall, soybeans planted as a doublecrop in June can yield nearly as much as full- season soybeans. In northern Illinois, the short season often makes doublecropping soybeans unfeasible, but wheat yields there tend to be higher due to more favor able weather and more productive soils. Wheat in the northern part of the state tends to be in areas where soils make corn and soybean production riskier, and on livestock farms where wheat provides opportunity to harvest straw, perhaps start a legume crop, and tile or haul manure before fall-harvested crops are harvested. Year In the mid-1990s, we started an experiment in western FIGURE l • State average yields of corn, soybeans, and Illinois to measure the performance of wheat in a 3-year wheat in Illinois, 1996 through 2006 (source: NASS). rotation and to compare yields and economic returns
48 ♦ 2007 Illinois Crop Protection Technology Conference in that system to the corn-soybean rotation and to 70 continuous corn and continuous soybeans. The 3-year rotation includes corn, soybeans, and wheat in both possible sequences (C-S-W and S-C-W), and it also includes tilled versus no-till as subplots within the main rotations. All crops in each sequence appear in separate plots each year. The experiments were established at two locations—on a productive silt loam soil at Monmouth, in Warren County, and on a productive creek-bottom soil near Perry, in Pike County.
Corn yields in the 3-year rotation at Monmouth were 6 Cont S Rot CS C-W-S W-C-S to 10 bushels higher than in the soybean-corn rotation, System and the S-W-C yield was slightly higher than the W-S- Figure 3 • Average soybean yields under four crop C yield (Figure 2). Continuous corn performed poorly, sequences at two tillage treatments at Monmouth, especially under no-till. Soybeans also yielded 4 to 6 Illinois. Data are averaged over 6 years, 2000 through bushels more in the 3-year rotation compared to the C-S 2005. rotation, and the soybeans in the C-W-S rotation yielded about 3 bushels more than in the W-C-S rotation (Figure 3). Continuous soybeans yielded 6 to 8 bushels less than 3-year sequence W-S-C, followed closely by W-C-S, C-S, and tillage had little effect on soybean yield. W heat which performed similarly to the S-C rotation (Figure in the C-S-W rotation yielded 5 to 6 bushels more than 5). Continuous soybeans had lower returns than the mul in the S-C-W rotation and about 3 bushels more when tiple-crop rotations, especially when tilled. Continuous tilled compared to no-till (Figure 4). corn, for reasons that are not clear, was by far the least profitable of all systems. No-till produced more return Returns in each of the crop sequences were compared than tilled soils in all cropping sequences. using costs given in Table 1, Prices used in this analysis were corn at $2.25 per bushel, soybeans at $5.80 per At Perry (data not shown), returns for continuous corn bushel, and wheat at $3.20 per bushel. There were no were much higher than at Monmouth, but continuous adjustments for government payments, nor was the corn still produced the least return of all sequences. At value of wheat straw (or other crop residue) included. this location, the C-S rotation performed the best, in The most profitable system under this analysis was the economic terms, and continuous soybeans produced
200 mConv T 180 90 ED No-till £ 160 80 ra 140 70 n 120 £60 2 100 0) "In 50 80 2 40 E 60 o ~ 30 O 40 20 20 0 Cont C Rot SC S-W-C W-S-C S-C-W C-S-W System Rotation
Figure 2 • Average corn yields undeT four crop Figure 4 • Average wheat yields under four crop sequences at two tillage treatments at Monmouth, sequences at two tillage treatments at Monmouth, Illinois. Data are averaged over 6 years, 2000 through Illinois. Data are averaged over 6 years, 2000 through 2005. 2005.
2007 Illinois Crop Protection Technology Conference ♦ 4 9 TABLE i • Estimated production costs foT corn, soybeans, and wheat in the rotation study (source: modified from Illinois Farm Business Farm Management Association records, with some adjustments).
Tillage and Pesticide Crop System planting Fertiliser $ per acre Seed Other Total
Continuous corn Conventional tillage 28 86 50 4 0 23 2 2 7 N o -till 8 86 50 4 0 23 207
Rotated corn Conventional tillage 23 7 2 39 4 0 23 197 N o -till 8 72 39 4 0 23 182
S oybean Conventional tillage 23 24 28 30 11 116 N o -tili 8 24 28 30 11 101
W h e a t Conventional tillage 18 4 9 8 24 9 108 N o -till 8 49 8 24 9 98
returns competitive with those from the 3-year rotations and that the three-crop sequence might hold economic under no-till. The order of crops in the 3-year rotation promise. had little effect on net returns from that system. So will wheat make a comeback in areas where nearly These results suggest that including wheat in the rotation all fields now grow corn or soybeans every year? All has a small, beneficial effect on corn and soybean yields three crops currently enjoy higher prices as a result of high demand and lower worldwide yields, especially of wheat, in recent months. The price signals for wheat are 250.00 especially strong, for hard wheat more than for the soft wheat that is commonly grown in Illinois. W heat also is the best of the three crops in providing cover for sloping soils to reduce soil loss during the noncropping season. In terms of economic potential, however, corn, with the proven ability to produce more than 200 bushels per acre in most fields in Illinois, remains the crop of choice for many producers, and is likely to remain so as demand for corn grows. W heat is, however, perhaps the best choice
Cont C Cent S C-S W -C-S W-S-C currently available as a third crop: it has a ready market, Cropping sequence it provides some stability within cropping systems, it spreads workloads and costs less to produce than other Figure 5 • Return over direct cropping costs for crops, and it can produce extra income from straw in fom crop sequences and two tillage treatments at some venues. Monmouth, Illinois. Data are averaged over 6 years, 2000 through 2005.
50 ♦ 2007 Illinois Crop Protection Technology Conference Wheat Disease Management
.. ■ Gregory Shaner
everal diseases can afflict wheat in the eastern Corn the season (late March through early May), this pathogen Belt, Among these are rusts, powdery mildew, leaf will predominate. Symptoms first appear on the oldest and glume blotch, and Fusarium head blight. Of leaves, commonly those near the soil surface. Subsequent theS three rusts that attack wheat, leaf rust is our greatest infections appear progressively higher up the plant and threat. Stem rust occasionally infects soft winter wheat, can lead to premature death of all leaves. Stagonospora but it develops best in hot weather (68°F to 86°F). W ith blotch likewise requires frequent, long periods of wetness the change to production of early-maturing varieties about on foliage, but is favored by higher temperatures (68°F to 50 years ago, the risk of stem rust diminished because 80°F). If wet weather persists into May, this disease can these varieties mature before the disease can become progress rapidly. Septoria infects only leaves; Stagonospora severe. Conversely, cool weather (50°F to 59°F) favors can infect heads as well, to cause glume blotch. stripe rust. In the Corn Belt, spring weather progresses In our region, rusts and leaf blotch rarely become severe so quickly from too cold to too hot that stripe rust does until after kernels have formed. Therefore, these diseases not have rime to become a problem. Temperature in this do not reduce the number of kernels per head. They region is typically favorable for leaf rust (59°F to 72°F), interfere with kernel filling, so grain is shriveled and has and this disease occurs to some extent every year. On a low test weight. Powdery mildew does much of its damage susceptible variety, rust spreads rapidly. It may increase earlier in the season. One of its main effects is to shut from only one or two infections per plant to complete down development of tillers. In a severely infected crop, destruction of foliage in less than 30 days. heads will fail to emerge on most tillers, or, if they do, Powdery mildew is more of a problem in Michigan and they produce no grain. Thus, only main culms produce Ohio than in Illinois and Indiana, possibly because of grain, and yield is reduced accordingly, cloudier weather in the former two state during the Fusarium graminearum (Gibberella zeae) causes head period of vegetative growth in the spring. Nonetheless, the blight. The same fungus causes stalk rot and ear rot of disease can be severe on susceptible varieties throughout corn and is a common decomposer of corn residue even in the region when weather is conducive. fields without pre-harvest stalk rot. The fungus produces Two fungi are mainly responsible for leaf blotch in the tiny fruiting bodies and spores on corn residue. When eastern Corn Belt: Stagonospora nodorum and Septoria temperatures remains in the range of 48°F to 86°F and tritici. Leaf blotch is severe when there are frequent rains relative hum idity is above 90% during much of the time throughout the spring and early summer. Several periods from a week before wheat flowers through late milk, the of more or less continuous light rain for two or three days disease will be severe. The fungus produces spores on corn are more favorable for disease development than more residue that infect wheat flowers and young kernels. The widely spaced, heavy rains. The optimal temperature range most vulnerable stage for infection is after anthers have for Septoria blotch is 59°F to 68°F, If night temperatures shed pollen but are still attached to the head. The fungus remain above 47°F and there is sufficient moisture early in infects these spent anthers, and from there invades the
2007 Illinois Crop Protection Technology Conference ♦ 5^ developing kernel. Once the fungus has infected a single Unfortunately, there is some concern that resistance to floret, it grows into the rachis and spreads up and down head blight does not always mean lower levels of DO N the spike to infect more kernels. Kernels infected early in the grain. are so shriveled that they are ejected with the chaff during Entomologists developed the fly-free planting date concept harvest. The harvested grain, however, will have poor many years ago to reduce the risk of damage by Hessian test weight and contain chalky kernels (tombstones). In fly. It turns out that this planting guideline also reduces addition to loss of yield and test weight, Fusarium pro risk of damage from powdery mildew, Septoria blotch, and duces mycotoxins, principally deoxynivalenol (DON), yellow dwarf (a viral disease). Powdery mildew develops in grain. especially well on wheat that has been provided high rates Production of resistant varieties is the chief means of of nitrogen fertilizer. Rust and leaf blotch may also be reducing damage from diseases. Varieties highly resistant favored by high nitrogen rates because the thicker canopy to rusts and powdery mildew have long been available, holds moisture on leaves. Planting after the fly-free date although not every variety on the market today is resis and avoiding excessive nitrogen rates reduces the risk of tant to these diseases. Efforts to breed for resistance to these diseases. Septoria and Stagonospora blotches have been under way Several foliar fungicides are registered for use on wheat for 50 years, but progress has been slow and limited. No against rusts, powdery mildew, and leaf and glume blotch. variety is highly resistant, particularly to Stagonospora, but Although sprayed fields usually have less disease, an some have moderate resistance. On these varieties, the economic return from treatm ent is not ensured. Time of upper two leaves remain green for 10 to 14 days longer application, disease pressure, and variety all influence the than they do on a susceptible variety, which protects yield outcome of treatment. None of the registered products and test weight to some degree. includes head blight on the label. Folicur is moderately Resistance to head blight has been a major breeding objec effective against this disease and has been available under tive for only the past 10 years. A few recently developed a Section 18 exemption in several states. This fungicide varieties have some resistance, and breeders will likely is applied at the onset of flowering. develop varieties with greater resistance in the future.
5* ♦ 2007 Illinois Crop Protection Technology Conference Development of Fusarium Head Blight-Resistant Wheat Varieties Frederic L. Kolb
cab, or Fusarium head blight (FHB), causes incidence/severity/kernel rating (ISK) index (Kolb and significantly lower grain yield, lower test weight, Boze 2003) as a means to better evaluate experimental reduced grain quality, and reduced milling yield, lines that combine several “types” of resistance. Verges andS the fungus produces trichothecene mycotoxins (such et al. (2006) confirmed that scab resistance needs to be as deoxynivalenol, or DON) that are detrimental to evaluated over several years and environments. both humans and livestock. The best way to minimize In years when environmental conditions favor infection, economic losses due to scab is through integrated pest scab has resulted in huge economic losses to wheat pro management combining a number of control strategies ducers; therefore, there is an immense need to develop including use of scab-resistant varieties, production of wheat varieties with high levels of resistance to this disease. several varieties that differ in maturity, and application The long-term objective in my wheat breeding project of a fungicide when necessary. An important component is the development of soft red winter wheat genotypes in controlling scab is the production of resistant variet with excellent scab resistance combined with high yield ies. Thus, introduction of scab-resistant wheat varieties potential, winter hardiness, acceptable milling and baking contributes to improved food safety and reduces losses quality, and resistance to other diseases. The short-term suffered by producers. objectives are to (1) combine genes for scab resistance Different types of host plant resistance to scab have been from diverse sources, (2) evaluate the breeding lines described, including (1) resistance to initial infection, produced from crosses involving several sources of scab (2) resistance to invasion of plant tissue by the fungal resistance, (3) identify breeding lines with better scab hyphae, (3) development of well-filled kernels in infected resistance than any of the parents, and (4) provide data plants, (4) inhibition of translocation or degradation of on scab resistance of current varieties to producers. deoxynivalenol or resistance to accumulation of myco Specific crosses have been made to combine genes for scab toxins, and (5) yield tolerance (Stack 2000). Resistance resistance from different sources into genotypes that can to scab is quantitative, and different mechanisms of be used in breeding programs developing scab-resistant resistance are controlled by different genes (Bai and varieties. Some populations include several soft red winter Shaner 1994, 2004). Development of varieties with a wheat lines with moderate resistance, or populations high level of scab resistance may require combining scab developed from crosses involving two or more diverse resistance from several sources (Singh and van Ginkel sources of scab resistance. Producers are attracted to the 1997). In the University of Illinois breeding program, highest yielding varieties. If these varieties are also scab we have emphasized this strategy of combining several susceptible, when the environment favors scab infection, “types” of scab resistance. We have placed much emphasis severe losses occur. Therefore, combining scab resistance on evaluation of the percentage of Fusarium-damaged with high yield potential and other traits required in a kernels (FDK), and we developed the successful, adapted variety is extremely important.
2007 Illinois Crop Protection Technology Conference ♦ 53 Wheat is most susceptible to infection to scab during other desirable agronomic traits. These lines are then and just after flowering. Under natural environmental evaluated for scab resistance in the field. conditions, scab evaluations are often confounded with 4. Evaluate experimental lines and currently grown variet time of flowering. To ensure that scab can be evaluated ies for scab resistance, and select lines using both the every year, we use a scab evaluation field nursery where greenhouse inoculation methods and the field evalu the plots can be misted daily for several weeks when the ation nursery. wheat is flowering. The nursery is inoculated using grain spawn scattered in the nursery. A mixture of isolates is 5. Evaluate scab-resistant lines for yield, agronomic traits, used in the culture of the inoculum. In addition, corn and resistance to other diseases. Scab resistance is only stalks are scattered in the nursery in the fall following one trait required in an adapted variety; therefore, wheat seedling emergence, and a spore suspension of a experimental breeding lines with scab resistance are mixture of isolates is sprayed on the corn stalks. also evaluated for many other characteristics. Experimental breeding lines for evaluation are planted in 6. Release breeding lines for commercial production. rows 3 feet in length, and an irrigation system provides When breeding lines with potential for commercial daily misting during flowering (three 45-minute to 1- production are developed, they are released to the hour periods in a 24-hour period). Rows of plants in the seed industry. Development of a variety from the time field are evaluated based on incidence and severity using a cross is made until a variety is released can take 10 a rating scale. Data are collected on incidence and sever to 12 years. In 2006, four wheat breeding lines were ity, and the FHB index is calculated. Incidence is based released for brand labeling. Several of these lines were on assessing the percentage of heads in a row that show produced in large increases in 2006 and should be in symptoms. Severity is based on assessing the percentage seedsmens fields in the fall of 2006 or 2007. of scabby spikelets in seven to ten heads per row. Visual Data are collected on the scab resistance of some current estimates of infected spikelets may not give an accurate varieties, and the information about the scab resistance assessment of kernel damage; therefore, prevalence of of numerous current varieties is available at the Illinois shriveled kernels (FDK, Fusarium-damaged kernels) is Variety Testing W eb site at http://vt.cropsci.uiuc.edu/ determined. The percentage of Fusarium-damaged kernels wheat.html. At the site, click on "Fusarium Head Scab (% FDK) is determined for each sample. The ISK index Ratings of Varieties.” is computed using the formula: 0.3 (% incidence) + 0,3 (% severity) + 0.4 (% FDK). The ISK index varies from Table 1 summarizes data from several years for varieties 0 to 100. Samples from the breeding lines evaluated are evaluated in the scab field nursery. This information can sent to Michigan State University for DON analysis. be used to aid in variety selection and to avoid planting The use of the ISK index and DON level for selection varieties that are very susceptible to scab. This is crucial is very important to ensure that breeding lines will be to the reduction of risk due to damage from scab infec acceptable to the milling and baking industry. tion. The development of scab resistant varieties includes the References following steps: Bai, G., and G. Shaner. 1994. Scab of wheat: Prospects for control. 1. Make crosses to create genetic variability. O ur emphasis Plant Disease 78:760-766. is on combining scab resistance with high yield and Bai, G., and G. Shaner. 2004. Management and resistance in other traits required for successful, adapted variet wheat and barley to Fusarium head blight. Annual Review of ies. Phytopathology 42:135—161. 2. Advance the populations for several generations. Kolb, F.L., and L.K. Boze. 2003. An alternative to the FHB 3. Select for scab resistance in segregating generations, and index: Incidence, severity, kernel rating (ISK) index (abstract). identify individuals with the highest level of resistance. In Proceedings of the 2003 National Fusarium Head Blight Thousands of heads are selected from populations Forum, Minneapolis, MN, December 13-15, 2003, U.S. with scab-resistant parents crossed to parents with W heat and Barley Scab Initiative, Michigan State University, high yield combined with excellent plant type and East Lansing, MI.
54 ♦ 2007 Illinois Crop Protection Technology Conference
— — — — — — — — — 3.2 3.5 5.8 5.1 3.1 3.2 5.0 4.5 2.6 2.4 3.3 4.9 4.5 2.5 2.7 7.1 23.0 DON — — — — — — — — — 35.2 38.3 55.3 57.7 63.0 37.2 30.1 40.8 43.6 55.3 65.7 43.3 58.2 23.7 44.8 60.6 44.1 (0 -1 0 0 ) IS K index — — — — — — — — — 3.0 3.4 10.6 19.5 16.0 11.4 19.7 50.0 38.4 27.0 28.0 20.4 21.1 42.6 43.4 47.7 44.2 — — — — — — — — — 33 53 33 30 33 37 53 37 30 20 40 40 47 63 47 43 43 (% FDK)2 (0-100) Kernel rating FHB index — — — — — — — — — (%) 14.7 57.9 52.1 64.9 31.1 63.6 51.6 52.3 56.3 38.2 32.6 57.5 62.6 40.5 47.4 46.3 42.5 Severity — — — — — — — — — 10.0 90.0 30.0 38.3 95.0 76.7 91.7 4 3 .3 24.3 80.0 23.3 31.7 63.3 75.0 25.0 48.3 86.7 ( % y Incidence 54.3 58.9 25.0 26.1 30.0 32.3 36.9 38.0 38.7 39.1 52.3 54.0 54.7 56.7 57.1 45.0 51.8 40.4 40.9 41.2 42.2 42.2 43.3 48.1 48.6 43.1 (0 -1 0 0 ) ISK index 4.4 6.2 14.9 19.7 33.9 37.3 37.9 32.8 23.8 20.9 20.6 27.1 34.6 34.1 34.6 43.6 47.3 21.3 26.9 27.1 24.1 23.1 31.7 38.2 43.1 40.1 7 13 30 15 37 53 22 30 37 27 33 27 25 27 30 20 37 27 37 38 43 47 50 43 27 25 2006 2005 (% FD K )2 (0 -1 0 0 ) Kernel rating FHB index (%) 16.6 44.7 11.0 58.8 63.7 34.8 55.2 56.7 59.3 60.5 42.4 47.6 40.6 60.2 42.4 62.8 62.3 55.2 40.6 65.3 47.8 66.9 60.1 63.2 42.1 56.5 Severity 33.3 33.3 55.0 75.0 53.3 66.7 56.7 61.7 73.3 56.7 35.0 56.7 53.3 41.7 50.0 26.7 60.0 40.0 61.7 76.7 60.0 60.0 71.7 41.7 60.0 51.7 (%Y Incidence Ernie name Bravo Entry Roane 25R51 25R54 25R37 25R47 25R63 FS 634 FS 645 Trum an FS 8309 FS 8302 JG L 603 Excel 173 Excel 361 Excel 307 Excel 176 Excel 442 Excel 211 Excel 399 Kaskaskia Excel 400-1 Coker 9511 McCormick Excel 410 tw Excel Brand Seeds (most resistant) to highest (most susceptible). Varieties highest resistant)susceptible). (most to (most with greaterhave lower resistance numbers. Excel Brand Seeds Excel Brand Seeds Excel Brand Seeds Company Pioneer Hi-Bred Int’l Public Excel Brand Seeds Excel Brand Seeds Excel Brand Seeds GROWMARK Public Excel Brand Seeds Public AgriPro COKER TABLE i • 2005-2006TABLE headevaluation scab FusaTium entries variety of from selected the University Illinois of trial. Soriedby 2006ISK index, lowest Pioneer Hi-Bred Int’l Pioneer Hi-Bred Int’l Pioneer Hi-Bred Int'l GROWMARK Ohio Seed Imp.Assn. Public Excel Brand Seeds Public GROWMARK Pioneer Hi-Bred Int'l GROWMARK JGL
2007 Illinois Crop Protection Technology Conference ♦ 55
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P- NO P- NO n F p- p- so p p r* crci fi> — — — — 3.8 5.0 5.9 6.2 5.9 7.4 4.8 5.2 4.2 n 13.5 1 1 £ O H r, s . ! s 3 £ w M rrs * £3 (u 3 00 55 S' g ** O 2. 2. era 2 .c^. p id- crc O ^ P 5‘ is g- r-t X P a p a“ 5‘ p fa a sr1 Oo a n> Co S' S a a Tj a a - n tu n 73 tu H — — — — 16.8 53.1 66.1 50.8 68.4 60.9 66.7 57.7 50.8 46.3 73.1 56.3 — — — — 18.0 51.8 37.5 51.0 33.1 21.4 40.2 60.2 43.6 37.1 42.1 64.8 — — — — 33 53 60 33 53 53 40 63 47 60 23.7 42.5 — — — — 50.2 65.3 61.9 67.1 51.6 54.1 22.4 54.1 66.4 54.7 44.9 49.7 — - — — 38.3 96.7 58.7 95.0 93.3 88.3 68.3 65.0 31.6 73.3 58.3 93.3 14.6 63.9 64.1 68.9 50.1 59.0 59.3 59.9 60.7 61.9 68.1 71.2 73.1 77.0 72.9 73.3 54.8 56.5 50.3 53.5 61.4 35.7 19.6 37.2 58.4 55.7 56.3 66.6 57.0 69.3 46.2 42.7 53 57 60 53 33 53 47 60 70 60 70 67 43 43 19.2 37.9 54.8 85.3 80.7 76.2 69.4 56.3 55.7 54.7 66,0 78.6 72.5 75.6 73.0 74.6 21.5 82.0 81.7 81.7 93.3 26.3 65.0 96.7 76.7 78.3 60.1 85.0 70.0 70.0 70.0 73.3 70.0 73.3 Sisson 25R78 FS 657 FS 637 Benton Cooper Branson Cardinal Madison Patterson Excel 392 LSD (0.05) Coker 9436 Coker 9553 Coker 9312 Test Average incidence = the percentage ofheads in a row with symptoms. GROWMARK GROWMARK Excel Brand Seeds Public Public Pioneer Hi-Bred Int'l Public 2Kernel rating = the percentage ofshriveled seed. AgriPro COKER Public AgriPro COKER AgriPro COKER AgriPro COKER AgriPro COKER AgriPro COKER
56 ♦ 2007 Illinois Crop Protection Technology Conference Managing Insects in Wheat: An Overview
Douglas W. Johnson
entucky is located in a unique ecological situa Scouting tion between the cold winters of the northern In general, Kentucky-grown grain should be scouted Prairie states and the very mild winters of the weekly to determine pest activity and plant growth stage DeepK South. Though cold enough to stop most insect from plant emergence to maturity when the temperature activity during midwinter, the great variation in date of is above 48°F, which provides the best description of pest first frost, fall onset of continuous cold, and spring onset status and plant stage and allows important management of general warm weather makes it particularly difficult decision to be made in a timely manner. An outline for to predict insect impact in any given year. taking this data in a standard format can be found in the In Kentucky, wheat is grown as a winter crop planted University of Kentucky Integrated Pest Management in the fall, usually following corn, and harvested the fol (UK-IPM) scout manual for small grains (Lucas 2006), lowing summer. Most often, varieties that mature early In addition, there are other methods of collecting data enough to allow planting of double-crop soybeans are on important pests, such as the use of pheromone-baited used (Sandell 2002).This production system divides the traps to capture adult moths (Johnson 1994c). Whatever insect pests into three groups: those that infest in the fall method you choose, use randomly assigned data collection and that either do or do not overwinter, and those that points to avoid selecting” your data (Johnson 1994b), infest in the spring. We will examine these pests in order of appearance through the production year. Insect Pests in General Order of Insect pests are common in Kentucky wheat. Typically, Appearance one can find all of these insects in almost every field every Note: In this paper, common and scientific names of year, but rarely do their populations grow to economi insects are from Common Names of Insects and Related cally important numbers. Nonetheless, each pest has the Organisms, an online database published by the Ento potential to cause significant damage under appropriate mological Society of America (http://www.entsoc. conditions. org/pubs/common_names). W hat will this information mean to Illinois farmers? Fall Pests Generally, the situation in southern Illinois is very similar to that in western Kentucky. Conversely, as one moves The fall armyworm, Spodopterafrugiperda (J.E. Smith), farther north, the likelihood of encountering these pests, is a common pest of several late summer- and early fall- especially in economically important situations, is very planted crops. Fall armyworm (FAW) cannot overwinter much reduced. In any given year, the importance of several in Kentucky, FAW migrates into Kentucky from the Gulf of these pests, particularly Hessian fly and the cereal Coast in midsummer, initially infesting corn and grain aphid-barley yellows virus complex, depends on the sorghum as its primary crop hosts. In late summer/early short-term weather— most importantly, temperatures. fall, as corn and sorghum begin to mature, FAW colonizes
2007 Illinois Crop Protection Technology Conference ♦ 57 newly seeded grasses. Damage is most common in lawns, lothrin (primarily Karate and Warrior) over the historic reclaimed land, ditch banks, roadsides, and similar areas, use pattern were quite evident (Johnson and Townsend but FAW may also infest small grains. FAW can result in 1999). Moreover, there has been some historic use of sys seedling death if it feeds on new plants before roots are temic insecticide seed treatments, primarily imidacloprid established. If plants are established, FAW feeding is more (Gaucho) and now thiamethoxam (Cruiser). Use of these like grazing. FAW can remain active until the first killing latter seed treatment products is likely to increase. frost and will survive longer where crop residue provides Control of the cereal aphid complex is relatively easy shelter from the cold (as with conservation tillage). to obtain. As with most other insect pests of wheat, it Infestation typically results from early planting. Often, is hard to decide whether treatment is warranted. The planting after the Hessian fly-free date will avoid infesta difficulty of finding aphids, combined with the small tion. Occasionally, frost and the onset of cold weather are number required for application, the relative low cost of late enough to allow infestation of small grains, even after insecticides, and the fear of catastrophic loss to BYD, the fly-free date. Insecticidal control is relatively easy, but probably results in more insecticide use than is needed there are no established thresholds. Damaged fields are to mitigate the risk. The treatment of these questions is sometimes replanted, but this is a risky technique. Many dealt with in the southeastern region in a new publication damaged plants will survive; thus, replanting may result due out soon (Flanders et al,, in press). in a denser than desirable stand. Very dense stands will, The H essian fly, Mayetiola destructor (Say), is another in turn, result in problems in the spring such as lodging common insect pest infesting small grains in the fall and increased armyworm and disease pressure. (Johnson 1993b). In general, planting after the "fly free” date will provide adequate control in Kentucky. Fall and Spring Pests Agronomic and cultural factors favoring strong stems The cereal aphid complex comprises four common and stand-ability of the plant are preferred, but, at last grain aphids: bird cherry-oat aphid, Rbopalosiphum examination, all resistance factors can be overcome by padi (Linnaeus); corn leaf aphid, Rbopalosiphum maidis the biotypes present in the state. There are no rescue (Fitch); greenbug, Scbizapbis graminum (Rondani); and treatments (foliar-applied insecticides), though use of English grain aphid, Sitobion avenae (Fabricius), which systemic insecticides as seed treatments and fall or spring are considered the most important aphid pests in our foliar applications of systemic insecticides have been region. In addition, the rice root aphid, Rbopalosiphum used in the Deep South to combat this problem. Here, rufiabdominalis (Sasaki), very likely plays an important in the presence of good agronomic practices, preapplied role, though little is known about this aphid in Ken insecticide treatment is not warranted. tucky. It is interesting to note that these aphids are not The wheat curl mite, Aceria tosicbella Keifer, is a common considered important for their direct damage. Though pest of wheat in Nebraska and other Plains states but some information on the importance of direct damage, is rarely a problem in the Midwest. Wheat curl mite particularly from the bird cherry-oat aphid, is coming (WCM) was first noticed in Kentucky in 1987, with a to light, they are by far more notorious for their ability larger outbreak in 1988 (Townsend et al. 1996). Since that to spread the viral pathogens that result in barley yellow time, a significant infestation of WCM mite occurred in dwarf (BYD) disease. On the other hand, there are at south central Kentucky in 2000, with smaller, scattered least 25 aphids that can move the yellows viruses among infestations in more recent years. plants. Regardless of the aphids present, the risk— real and perceived— of barley yellow dwarf, and, by association, It was first believed that outbreaks of this pest were the the cereal aphid complex, is undoubtedly the major driver result of mites carried in on winds from more western of insecticide use in Kentucky-grown wheat (Johnson production areas. Though this is possible, and wind is and Townsend 1999). a method of dispersal, it appears more likely that this outbreak occurred because of the lack of weed control Though other insects may require insecticidal control from (thus, an increase in volunteer wheat) in soybeans during time to time, only the cereal aphids are routinely treated. the preceding summer. Volunteer wheat provides a“green Beginning in the early 1990s, increases in insecticide use, bridge” that may have allowed W CM to “oversummer” especially the systemic disulfoton (Di-Syston), and, in and build into much larger than normal numbers. This the mid-1990s, the synthetic pyrethroid lambda-cyha- is the usual cause of economic problems with W CM in
58 ♦ 2007 Illinois Crop Protection Technology Conference the Western states. Typically, there would be no green stands, especially with lodging and cool, cloudy springs, bridge in Kentucky. Conversely, in some poor soybean favor AW populations. Insecticidal control is relatively production years, weed control is reduced or abandoned; easy, if necessary. thus, volunteer wheat remains in fields. Important Natural Enemies Spring Pests There are many natural control agents operating in the The cereal leaf beetle, Oulema melanopus (Linnaeus), small grain fields of Kentucky. As previously mentioned, was first noted feeding in south central Kentucky in caterpillars parasitized by tachinid flies, plus braconid the mid-1980s (Johnson 1993a). Since that time, it has wasps (Hymenoptera; Braconidae) and infections by moved generally westward to the Mississippi River coun fungal and viral pathogens are often seen. Braconid para ties. Cereal leaf beetle (CLB) is a sporadic pest with a sitoids in the genus Aphidius have been collected from the tendency to damage the later-maturing varieties. grain aphids. In addition, a plethora of predators, such as ground beetles, (Coleptera: Carabidae) and syrphid Control of CLB is comparatively easy. Still, determin flies (Diptera: Syrphidae), are easily observed. Though ing the need to control in a timely fashion is the more often given short shrift, these natural controls, combined important decision. Work done in the late 1990s (Herbert with good cultural practices, probably account for much and Van Duyn 1999) produced scouting procedures and of the insect pest control in Kentucky wheat. thresholds that are currently in use. However, this insect is so rarely a problem that it is likely the “old” threshold Pesticide Strategies of one CLB per head-bearing stem is most often used, except in the most highly managed wheat. Insecticide use is an important tool in managing insect pests in small grains (Johnson, Insecticide Recommen T h e armyworm, Pseudaletia unipuncta (Haworth), dations, updated annually). Still, whether, when, and how also known as the “true armyworm,” is usually the first applications are made are often more important than pest of wheat to appear in the spring (Johnson 1994a). which insecticide is used. This is especially true when Armyworm (AW) makes its annual appearance each calculating economic returns. spring in “flights” of the adult moths. These flights can be monitored by capturing males, using pheromone-baited Soil-Applied Insecticides traps (Johnson and McNeill 1993; Johnson 1994c). The numbers caught using this technique can provide advance The decision to use soil-applied insecticides must be warning of the insect, allow calculation of when the made before planting. Treatments are very general, are damaging stage (worm) will appear (Johnson et al, 1998), broadcast over a wide area, and affect many animals other and can be compared to trap capture data from previous than the target pests. Few insecticides are available, and years (Lucas, Insect Trap Data, various dates). most are relatively toxic.
AW is very common in Kentucky but only rarely does Seed-Applied, Systemic Insecticides damage sufficient to warrant control. In spite of this, spectacular outbreaks of this pest do occur. One recent Like soil insecticides, seed-applied insecticides must outbreak occurred in 2001. In that year, our early peak trap be chosen before planting—in fact, when the seed is captures were more than three times the average (Lucas, purchased. Treatments are more targeted and primarily Insect Trap Data and IMP Trap Counts, various dates). affect insects that feed directly on the plant. They are a Very large populations appeared first in the South, then good choice for crops at increased risk to BYD (early progressively through the Midwest into Canada. Consider planted) but are relatively more expensive than other able damage was done to the first cutting of grass hay in applications. Kentucky. Conversely, effects on small grains are debatable because of the late occurrence of the infestation. Foliar-Applied Insecticides AW is most often controlled by naturally occurring The decision to use foliar-applied insecticides can be predators and parasitoids. For example, eggs of tachinid made as pests begin to appear. Like the soil insecticides, flies (Diptera: Tachinidae) are commonly found just foliar applications are general applications made over a behind the head on armyworm larvae. Very dense plant broad area and affect many animals other than the target
2007 Illinois Crop Protection Technology Conference ♦ 59 pests. If, however, they are targeted in time and area and Service Publication No. ENT- 47 (http://www.uky.edu/Ag/ based on pest threshold values, they are probably the PAT / recs/crop/pdf/Entfact-47.pdf). most cost effective. They require the most management Johnson, D,, and S. McNeill. 1993. Plans and Parts List for the skill to be used correctly. “Texas” Style Cone Trap for M onitoring Certain Insect Pests. University of Kentucky Entomology Fact Sheet No. 010 References (http://www.uky.edu/Ag/Entomology/entfacts/fldcrops/ You may find the references listed below to be of some ef010.htm). use. Nonetheless, you should recognize that entomolo Johnson, D., and L. Townsend. 1999. Aphids and Barley Yellow gist and crop production specialists in your state(s) will D warf (BYD) in Kentucky-Grown W heat. University of Ken have similar publications tailored for your production tucky Entomology Fact Sheet No. 121. (http://www.uky. area(s). edu/ Ag/Entomology/entfacts/fldcrops/efl21.htm).
Entomological Society of America. No date. Common Names of Johnson, D., R, Bessin, and L. Townsend. 1998. Predicting Insect Insects and Related Organisms (http://www.entsoc.org/pubs/ Development Using Degree Days. University of Kentucky common_names). Entomology Fact Sheet No. 123 (http://www.uky.edu/Ag/ Entomology/entfacts/fldcrops/efl23.htm). Flanders, K., A. Herbert, D. Buntin, D. Johnson, K. Bowen, J. Murphy, J. Chapin, and A. Hagan. In press. Barley Yellow Lucas, P. (ed). 2006. Kentucky Integrated Crop M anual for Field D w arf in Small Grains in the Southeast. Auburn University, Crops: Small Grains. University of Kentucky Integrated Pest Auburn, AL. Management Publication No. IPM-4. (http://www.uky. edu/Ag/IPM/manuals/ipm4smgr.pdf). Herbert, Jr,, D.A., andJ.W. Van Duyn. 1999. Cereal L eaf Beetle Biology and M anagement. Virginia Polytechnic Institute and Lucas, P. Various dates. Insect Trap D ata (archive). University State University, Publication No. 444-350 (http://www.ext. of Kentucky Integrated Pest Management (http://www.uky. vt.edu/pubs/entomology/444-350/444-350.htm l). edu/Ag/IPM/trapdata/trapdata.htm).
Johnson, D. 1993a. Cereal Leaf Beetle in Kentucky W heat. Univer Lucas, P. Various dates. IPM Trap Counts (weekly). University sity of Kentucky Entomology Fact Sheet No. 107 (http://www. of Kentucky Integrated Pest Management (http://www.uky. uky.edu/Ag/Entomology/entfacts/fldcrops/efl07.htm). edu/Ag/kpn/kpn_06/pn060925.htm#trap).
Johnson, D. 1993b. Hessian Fly in Kentucky. University of Ken Sandell, L. (ed). 2002. Crop Profile for W inter W heat in Kentucky. tucky Entomology Fact Sheet No. 101 (http://www.uky. NSF Center for Integrated Pest Management (http://pestdata. edu/ Ag/Entomology/entfacts/fldcrops/efl01.htm). ncsu.edu/cropprofiles/docs/KYwheat.html),
Johnson, D. 1994a. Armyworms in Small Grains. University of Townsend, L., D. Johnson, and D. Hershman, 1996. W h e a t Kentucky Entomology Fact Sheet No. I l l (http://www.uky. Streak Mosaic Virus and the W heat Curl M ite. University of edu/Ag/Entomology/entfacts/fldcrops/eflll.htm). Kentucky Entomology Fact Sheet No. 117 (http://www.uky. edu/ Ag/Entomology/entfacts/fldcrops/efll7.htm). Johnson, D. 1994b. Procedures for Selecting Random Locations for Sampling. University of Kentucky Entomology Fact Sheet No. 118 (http://www.uky.edu/Ag/Entomology/entfacts/ Additional References fldcrops/efll8.htm). Entomology Fact Sheets. Published by University of Kentucky Entomology (http://www.uky.edu/Ag/Entomology/ Johnson, D. 1994c. Using Pheromone Traps in Field Crops. Univer entfacts/eflists.htm). sity of Kentucky Entomology Fact Sheet No. 112 (http://www. uky.edu/Ag/Entomology/entfacts/fldcrops/efll2.htm). Kentucky Pest News (newsletter). Published weekly during field crop season, biweekly in winter. (http://www.uky.edu/Ag/ Johnson, D. Updated annually. Insecticide Recommendations for kpn/kpnhome.htm). Small Grains. University of Kentucky Cooperative Extension
6o ♦ 2007 Illinois Crop Protection Technology Conference Glyphosate-Resistant Palmer Amaranth Impacts Southeastern Agriculture A. Stanley Culpepper and Alan C. York
almer amaranth is among the three most trouble a cotton grower in Macon County, Georgia, was unable some weeds in Georgia cotton, peanuts, and soy to control Palmer amaranth with glyphosate in 2004. beans and is among the top five most troublesome weedsP in most other southeastern states (Webster 2005), Confirming Palmer Amaranth Resistance It is currently the most prevalent Amaranthus species in to Glyphosate Georgia agronomic crops, which is likely in response to its Field competitiveness and aggressive growth habit and prolific seed production. Compared with common waterhemp, The experiment was conducted in two fields in Macon redroot pigweed, and tumble pigweed, Palmer amaranth County in 2005. Treatments included the potassium salt had the greatest values for plant volume, dry weight, and of glyphosate at 0, 1.0, 2.25, 4.5, 6.7, and 9.0 lb a.i,/A leaf area (Horak and Loughin 2000). Additionally, the applied at 15 GPA, Palmer amaranth heights and densities rate of height increase per growing degree day for Palmer at time of treatment ranged from 2 to 4 inches and 10 amaranth was 24% to 62% greater than for the other plants per square foot, respectively, at one location and Amaranthus species. 3 to 5 inches and 40 plants per square foot at the second location. Glyphosate at 1,0, 2.25, 4.5, 6.7, and 9.0 lb/A A rapid growth rate and tall stature make Palmer ama controlled emerged Palmer amaranth 8%, 17%, 46%, ranth extremely competitive with crops. Palmer amaranth 70%, and 82%, respectively, 28 days after application. reduced corn yields 11% to 91%, with 0.5 to 8 plants In our experiment, glyphosate at 12 times the recom in 3.3 feet of row (Massinga et al. 2001; Massinga and mended rate, or 9.0 lb/A, failed to provide commercially Currie 2002) and reduced soybean yield 17% to 68%, acceptable control. with 0.33 to 10 plants in 3.3 feet of row (Klingaman and Oliver 1994). Cotton lint yields in Texas decreased Greenhouse linearly from 13% to 54% as Palmer amaranth density increased from 1 to 10 plants in 30 feet of row (Morgan Mature Palmer amaranth seeds from the suspect Macon et al. 2001). County field site were collected after being treated and surviving three glyphosate (0,75 lb/A) applications. The Since commercialization of Roundup Ready technology, seedlings (FI generation) were treated with glyphosate some southeastern growers have used this technology at 1.0 lb/A in the greenhouse and control was only 54%. in a monoculture system and have relied exclusively on Plants surviving this 1.0 lb/A application of glyphosate glyphosate (Roundup and others) applied multiple times were grown to maturity and crossed. Mature seed (F2 each season to manage Palmer amaranth and other weeds. generation) were harvested and then screened to deter From commercialization until 2004, these glyphosate mine the level of resistance relative to a known sensitive programs in Roundup Ready technology effectively and biotype. economically controlled Palmer amaranth. Unfortunately,
2007 Illinois Crop Protection Technology Conference ♦ 6l Seedlings 3 to 5 inches tall were treated with 12 rates of ing than control in soybeans or corn. In corn, growers a potassium salt of glyphosate, The level of glyphosate have several effective options including programs using needed to control the Macon County population was eight atrazine plus a chloroacetamide (Dual, Outlook, etc.) times that of the known susceptible biotype. This experi herbicides followed by 2,4-D or dicamba if needed. In ment, in conjunction with the field experiment, confirmed soybeans, flumioxazin (Valor) and the chloroacetamides that the Palmer amaranth infesting the farm in Macon applied at planting have also been effective if activated by County, Georgia, is indeed resistant to glyphosate. rainfall or irrigation. Postemergence control in soybeans is often more challenging than soil-applied options, but At this time, research is under way to confirm suspected several diphenylethers (Blazer, Reflex, etc.) are available resistant bio types of Palmer amaranth in North Carolina for use and can be effective if growers are timely with and South Carolina. Suspected resistant populations have applications. However, cotton production will likely been observed in a number of locations in both states. be more costly and challenging for growers. More than Additionally, glyphosate resistance is suspected, but yet 95% of the cotton acreage in the Southeast is Roundup confirmed, in common ragweed in North Carolina and Ready because glyphosate effectively controls Palmer common cocklebur in South Carolina. amaranth. Once Palmer populations become resistant to Future Impact on Southeastern Row Crop glyphosate, the only other postemergence over-the-top Agriculture herbicide options in conventional or Roundup Ready cotton are ALS herbicides such as pyrithiobac (Staple) This is the worlds first confirmed case of glyphosate and trifloxysulfuron (Envoke). Research is already under resistance in an Amaranthus species (Heap 2005; HRAC way investigating Palmer amaranth populations that are 2005), and it is a significant finding with serious ramifi likely resistant to both glyphosate and the ALS herbi cations for future weed management. Palmer amaranth cides, which unfortunately leaves no over-the-top control is already one of the most troublesome weeds of agro options in these cotton cultivars. Growers will be forced nomic crops across the southern United States (Webster to rely heavily on at-plant residual herbicides, which can 2005); resistance to glyphosate will only exacerbate the be effective if activated by rainfall or irrigation, but with problem, especially in light of the widespread planting the slow growth of cotton these at-plant options will of glyphosate-resistant crops. Rapid spread by pollen is likely not provide long-enough control for growers. One expected in this dioecious species (forced outcrossing). study investigated exactly what it would take to remove Moreover, resistance to other herbicides, such as dini- Palmer amaranth (10% glyphosate resistant and 90% troanilines and acetolactate synthase inhibitors (Heap glyphosate sensitive) from a grower’s 75-acre field. In 2005), limits the options to control glyphosate-resistant that field during 2006, we spent $50 in herbicides plus Palmer amaranth. an additional 220 hours of hand weeding. O ther Amaranthus species are prevalent in all regions of North America, especially in the midwestern and southern References areas of the United States, where glyphosate-resistant Franssen, A.S., D.Z. Skinner, K. Al-Khatib, M.J. Horak, and crops have been broadly adopted. Amaranthus species, P.A. Kulakow. 2001. Interspecific hybridization and gene including Palmer amaranth, can outcross with other flow of ALS resistance in A m a r a n th u s species. W eed Science related monoecious and dioecious species (Franssen et al. 49:598-606. 2001; Tranel et al. 2002; Trucco et al. 2005). Glyphosate Heap, I.M. 2005.International Survey of Herbicide Resistant Weeds resistance in this particular Palmer amaranth population (http://www.weedresearch.com). will likely spread to other adjacent Amaranthus species by outcrossing, limited only by movement of viable pollen Herbicide Resistant Action Committee (HRAC). 2005. G u id e - in the atmosphere. line to the M anagem ent of Herbicide Resistance (http://www. plantprotection.org/hrac/guideline.html).
Initial Results from Glyphosate-Resistant Horak, M.J., and T.M. Loughin. 2000. Growth analysis of four Palmer Amaranth Research A m a r a n th u s species. W eed Science 48:347-355. Although research has been conducted for only two years, Klingaman T.E., and L. R. Oliver. 1994. Palmer amaranth there are several conclusions that can be drawn from our ( A m a r a n th u s p a lm e r i) interference in soybeans (Glycine max). efforts. Control in cotton will be much more challeng W eed Science 42:523-527.
62 ♦ 2007 Illinois Crop Protection Technology Conference Massinga, R.A., and R.S. Currie. 2002. Impact of Palmer amaranth dioecious weedy A m a r a n th u s species. Theoretical and Applied (Amaranthus palmeri) on corn ( Z e a m a y s ) grain yield and yield G e n e tic s 105:674-679. and quality of forage. W eed Technology 16:532-536. Trucco, R, M.R.Jeschke, A.L. Rayburn, and P.J. Tranel, 2005. Massinga, R.A., R.S. Currie, M.J. Horak, and J. Boyer, Jr. 2001. Promiscuity in weedy amaranths: High frequency of female Interference of Palmer amaranth in corn. W eed Science tall waterhemp (Amaranthus tuberculatus) x smooth pigweed 49:202-208. (A, h y b r i d u s ) hybridization under field conditions. W e e d S cie n c e 53:46-54. Morgan, G.D., P.A. Baumann, and j.M. Chandler. 2001. Com petitive impact of Palmer amaranth ( A m a r a n th u s p a lm e r i) on Webster, T.M. 2005. Weed survey—Southern states: Broadleaf cotton (Gossypium hirsutum ) development and yield. W e e d crops subsection. In Proceedings of the Southern W eed Science T e c h n o lo g y 15:408-412. S o c ie ty 58:291-304.
Tranel, P.J.,J.J. Wassom, M.R.Jeschke, and A.L. Rayburn. 2002. Transmission of herbicide resistance from a monoecious to a
2007 Illinois Crop Protection Technology Conference + 63 Glyphosate-Resistant Waterhemp: Out Experiences in Missouri
Kevin Bradley
erhaps no single event in the history of agriculture biotypes that we discovered in two separate locations in has changed weed management to the extent that northwestern Missouri, also in 2005. Roundup Ready crops have. In 2005,89% of the In 2006, we initiated a number of field experiments on soybeanP acreage in the United States was planted with one of these populations in Platte County, Missouri, This Roundup Ready soybean varieties, while approximately population was discovered in fields with a continuous 36% of the corn acreage was planted with herbicide- soybean “rotation” in which glyphosate has been used resistant corn hybrids, the vast majority of which are also repeatedly as the sole active ingredient since 1996. Roundup Ready. Many have speculated that Roundup Ready corn acreage in the U.S. will continue to increase In the corn experiments that we have conducted at this in the next few years, which would place much of the site, we have observed excellent waterhemp control with acreage in a Roundup Ready soybean-Roundup Ready virtually all of our preemergence and preemergence corn rotation. And, even though it is hoped that most followed by postemergence programs (Table 1). As growers will apply a preemergence herbicide treatment to expected, the glyphosate-only program provided little to corn, it is probably safe to assume that the vast majority of no control of the waterhemp. However, postemergence- the postemergence applications in either Roundup Ready only programs consisting of two applications of Liberty corn or soybeans will involve glyphosate. This scenario or Liberty + Atrazine also provided excellent control. We represents a tremendous selection pressure that will be urge growers to use caution in the interpretation of these placed on weeds to develop resistance to glyphosate. results, because similar levels of season-long waterhemp control are rarely achieved with these preemergence treat In fact, in recent years, a num ber of glyphosate-resistant ments in other corn fields throughout the Midwest. We weed biotypes have already been identified. These resistant attribute the high levels of waterhemp control that we species have been identified primarily in locations where a observed in these experiments to the history of the site in Roundup Ready crop, such as soybean or cotton, has been question; this location had not been planted in corn and planted continuously without rotation and where repeated had not received standard applications of preemergence applications of glyphosate have been made year after corn herbicides such as atrazine for at least 20 years. We year. Some of the more recent examples of these species have not observed similar levels of waterhemp control include a number of glyphosate-resistant horseweed, or with these same residual treatments in other parts of marestail, biotypes located throughout the central and the state. The results from these experiments reveal a eastern United States; a glyphosate-resistant common seemingly simple' solution to the problem of glyphosate- ragweed biotype discovered in Missouri and Arkansas resistant waterhemp—rotate into corn. However, future in 2004; glyphosate-resistant Palmer amaranth biotypes research will examine the impact of crop rotation on discovered in Georgia, Tennessee, and North Carolina the stability of glyphosate resistance in the waterhemp in 2005; and glyphosate-resistant common waterhemp population over time.
64 ♦ 2007 Illinois Crop Protection Technology Conference TABLE i • Influence of preemergeme and postemergence herbicide programs on glyphosate-resistant waterhemp control in corn.
Postemergence treatments1 Callisto Distinct Liberty Roundup Omax PRE or E-POST treatments None (2 fl oz) (4 oz) (32 fl oz) (22 fl oz)
Common Waterhemp Control 2 Months After Planting
Degree Xtra (3,7 qt) 99 a 99 a 99 a 99 a 99 a
Lexar (3 qt) 97 a 99 a 99 a 99 a 99 a Atrazine (2 qt) 99 a 99 a 99 a 98 a 98 a
Radius (22 oz) 85 b 98 a 99 a 99 a 99 a
Liberty (32 fl oz) — — — 97 a — Liberty (32 fl oz) + Atrazine (2 qt) — — — 99 a — Roundup Omax (22 fl oz) — — — — 25 c Roundup Omax (22 fl oz) + Atrazine (2 qt) — — — — 99 a
1 Roundup and Liberty POST treatments applied with AMS; Callisto applied with COC and UAN. 2 Means followed by the same letter are not different (LSD 0,05).
In our soybean experiments, we observed, poor control OriginalMax to a Phoenix or Ultra Blazer treatment of waterhemp with glyphosate, even at especially high did not improve control of glyphosate-resistant water rates (Table 2). In fact, 53% of the waterhemp population hemp compared to these treatments alone. Conversely, survived treatment with 176 fluid ounces of Roundup the addition of Phoenix or Ultra Blazer to a Roundup OriginalMax, indicating that there are a high number of OriginalMax treatment did not increase control of glypho- resistant individuals in this waterhemp population. We have also observed TABLE 2 • Influence of glyphosate and glyphosate tank-mixes on poor waterhemp control with other glyphosate-Tesistant waterhemp survival 6 weeks after treatment (WAT). postemergence soybean herbicides Waterhemp survival such as the protox-inhibiting herbi Treatments1 Rate (product/A) 6 WAT2'3 (%) cides Phoenix, Flexstar, Ultra Blazer, and Aim, which suggests to us that we Roundup OriginalMax 22 fl oz 98 a may have resistance to these herbicides 44 fl oz 89 a in this waterhemp population as well 88 fl oz 63 b (Table 2, Table 3), The likelihood of protox resistance in addition to 176 fl oz 53 b glyphosate resistance will be the focus Roundup Omax + Phoenix 22 fl oz + 8 fl oz 94 a of much greenhouse research that will Roundup Omax + Flexstar 22 fl oz + % pt 95 a be conducted in the near future. Roundup Omax + Ultra Blazer 22 fl oz + 1.5 pt 95 a As illustrated in Table 3, it seems clear that a program approach that includes Roundup Omax + Aim 22 fl oz + 14 fl oz 97 a an application of a preemergence and a Roundup Omax + Firstrate 22 fl oz + 0.3 oz 95 a postemergence herbicide will be one of Roundup Omax + Butyrac 22 fl oz + 2 fl oz 98 a the only effective options for the m an agement of this glyphosate-resistant 1 All treatments applied with AMS at 2.5 lb/A. waterhemp population. W ithin these 2 Number of flagged waterhemp plants/total (total = 80) living 6 weeks after treatment. programs, the addition of Roundup 3 Means followed by the same letter are not significantly different (LSD 0.05).
2007 Illinois Crop Protection Technology Conference ♦ 65 sate-resistant waterhemp compared to the Roundup Simply put, two alternatives to the problem of glyphosate- OriginalMax treatment alone. Based on what we know resistant weeds exist. Farmers can manage the develop about the glyphosate resistance in this population and ment of resistance by not spraying glyphosate continually what we suspect about the protox resistance in this popula in the same area over time and by rotating to herbicides tion, these results indicate that an effective preemergence with other modes of action (proactive resistance manage herbicide is the most important component. Spartan and ment), or farmers can choose to deal with a glyphosate- Boundary were some of the better preemergence herbicide resistant weed once it occurs by using more expensive treatments for glyphosate-resistant waterhemp, but it is weed control measures at that time. The question boils important to note that these results are from one year down to “Do I pay a slightly higher price today for weed only and that season-long waterhemp control will rarely management strategies that delay or prevent glyphosate be achieved with any preemergence soybean herbicide. resistance or do I pay a much higher price in the future All postemergence-only treatments provided poor control when a glyphosate-resistant weed requires me to use of glyphosate-resistant waterhemp. more expensive control measures?” The situation that exists with glyphosate-resistant Recently, some weed scientists have published an inter common waterhemp in Missouri should be viewed as esting study that attempts to address many of these a big, flashing warning sign to any grower in any state important issues. In that study, the authors found that who has been planting a continual Roundup Ready crop it would be better economically to proactively manage -soybeans for many years in a row or even to growers resistance— or use alternative weed control strategies who are planting a Roundup Ready soybean-Roundup now in an effort to delay resistance. Some examples of Ready corn rotation. Also, there is no reason to believe proactive strategies for Midwestern corn and soybean that independent selection events cannot occur throughout producers who have problems with waterhemp would different areas, meaning that other farmers who have been be, for example, to in a continuous soybean rotation and who have relied ♦ Rotate to conventional corn hybrids and get out of a solely on glyphosate may also start to see instances of continuous Roundup Ready soybean rotation if at all glyphosate-resistant common waterhemp in their fields possible. as well. The last thing we need in our corn and soybean production systems is to lose the profitability of our ♦ Use conventional preemergence and/ or postemergence current weed management programs as a result of the herbicide programs that are effective on common development of glyphosate-resistant weeds. waterhemp in corn, given that most producers will
TABLE 3 • Influence of preemergence and postemergence programs on glyphosate-resistant waterhemp control 3 months after planting.
Postemergence treatments1
Preemergence Ultra Roundup Roundup Omax Roundup Omax treatments Phoenix Blazer Omax + Phoenix + Ultra Blazer None
% Waterhemp Control 3 Months After Planting
Valor 68 81 66 86 85 58 Spartan 89 94 91 95 95 80
INTRRO 76 85 73 86 88 45 Boundary 88 88 81 95 94 80
None 23 23 0 5 3 0
LSD (0.05) 12
1 AMS added to all Roundup treatments; NIS added to Phoenix and Blazer treatments when applied alone.
66 ♦ 2007 Illinois Crop Protection Technology Conference plant Roundup Ready hybrids and utilize glyphosate (Phoenix, Cobra, Reflex, Flexstar, Ultra Blazer) other as the sole herbicide for weed control in soybean. than glyphosate either applied alone or as a glyphosate tank-mix partner should also be an option (as long as ♦ In Roundup Ready soybeans, first consider the use of protox resistance is not suspected), but these prod preemergence herbicides that have good activity on ucts are generally more expensive than some of the common waterhemp (Valor, Spartan, Dual, INTRRO, preemergence options, such as Valor, listed above. etc.). The use of an effective postemergence herbicide
2007 Illinois Crop Protection Technology Conference ♦ 67 Predicting the Evolution and Spread of Glyphosate-Resistant Waterhemp
Patrick J. Tranel
ince the commercialization of glyphosate-resis- Two Different Types of Glyphosate - tant soybean, anecdotal reports of inadequate Resistant Waterhemp? waterhemp control with glyphosate have steadily The exact mechanism by which the Missouri waterhemp increased.S However, several factors other than resistance population is resistant to glyphosate has not yet been have contributed to the inadequate control. For example, determined. Similarly, we do not yet know the genetics the excellent weed control from glyphosate that farmers of this resistance, including how resistance is passed observed when first using glyphosate-resistant soybeans down from parent to offspring. A relevant observation, probably resulted in some complacency toward glyphosate however, is that glyphosate resistance is fairly uniform and, subsequently, in farmers “pushing the system” by and consistent within the population (i.e., there are few applying rates that were too low on plants that were too sensitive plants in the population). This observation large. Even in cases where adverse environmental factors suggests that the resistance has a simple genetic basis; and improper application did not appear to account for more specifically, it suggests that a single gene confers inadequate waterhemp control with glyphosate, subse the resistance. quent glyphosate treatment (either in the same season or in the following growing season) typically provided In contrast to the single-gene resistance that may be excellent control, ruling out a truly glyphosate-resistant present in the Missouri population, research in my population as the culprit. Consequently, despite anec laboratory suggests that glyphosate resistance also can dotal reports of inadequate waterhemp control with evolve in waterhemp as a multigenic trait. Several of our glyphosate, glyphosate resistance in waterhemp had not recommendations for herbicide-resistance mitigation are been confirmed. independent of the underlying genetics of the resistance trait. However, other recommendations depend on This changed in 2005, with the confirmation that a whether the resistance is mediated by one or multiple waterhemp population in Missouri was, in fact, resis genes. As one example, the strategy of using the maximum tant to glyphosate. About the same time, populations of labeled use rate to mitigate resistance evolution likely will Palmer amaranth (a close relative of waterhemp with a be much more successful for multigenic resistance than more southern distribution) also were confirmed resis for single-gene resistance. Thus, evidence suggesting that tant to glyphosate. Details on the glyphosate-resistant both single- and multi-gene glyphosate resistances can waterhemp and Palmer amaranth populations will be evolve in waterhemp certainly does not help to clarify the provided at other presentations during the conference. debate on how to best mitigate glyphosate resistance. Given that we now know glyphosate-resistant waterhemp is a reality, my focus will be,“W hat can we do to mitigate Gene Flow in Waterhemp this threat to our current weed management systems that are reliant (over-reliant) on glyphosate?” The genetics underlying a trait (e,g., herbicide resistance) can influence how rapidly that trait spreads via pollen.
68 ♦ 2007 Illinois Crop Protection Technology Conference Specifically, resistance that is controlled by a single gene waterhemp resistant to both herbicide groups sooner will be transferred via pollen flow from one population to rather than later, (This, in fact, apparently has already another much more rapidly than if resistance is controlled happened in the glyphosate-resistant waterhemp popula by multiple genes. Gene flow via pollen is particularly sig tion in Missouri.) Another concern is that waterhemp can nificant for a dioecious species such as waterhemp. Being hybridize with other pigweed species. Thus, there is the dioecious^ waterhemp consists of plants that are either possibility (although it has not been demonstrated yet) male or female; consequently waterhemp has evolved that glyphosate resistance in waterhemp could lead to, for mechanisms to increase the probability that pollination example, glyphosate resistance in smooth pigweed. will occur even when a female plant does not happen to be growing in immediate proximity of a male plant. Such Management Recommendations mechanisms include the small size of the pollen grains So what do we do? Well, it might be helpful to remind (about one-fifth that of corn pollen) and high aperture ourselves of what not to do. One thing we have learned density (over twice that of most monoecious pigweeds). from the history of pest management is that over-reli These characteristics of waterhemp pollen allow it to be ance on a single management tool is a recipe for failure. carried long distances even at moderate wind speeds. Increased adoption of glyphosate-resistant corn—and In regard to female waterhemp plants, stigmas remain concomitant increased use of glyphosate—will certainly receptive for several days, increasing the odds that the increase the selection intensity for glyphosate-resistant flowers will be pollinated. waterhemp and other weeds. The most effective strategy The pollination biology of waterhemp makes legitimate for mitigating glyphosate resistance will be increased use the concern that glyphosate resistance that has evolved of other weed control strategies. Because of the potential in your neighbor's field will become your problem, too. for glyphosate resistance to spread via pollen, even a Also, because most herbicide resistances are conferred glyphosate-sensitive female waterhemp plant surviving by single genes, pollen movement among populations in your field has the potential to produce glyphosate- readily leads to 'stacking” of the different resistances. resistant progeny. Optimal management of the crop (e.g., For example, if you have selected glyphosate-resistant pre-plant operations, planting density, spacing, etc.) and waterhemp in your field, and your neighbor has selected a use of a soil-residual herbicide will foster a more timely waterhemp population resistant to P P O inhibitors (e.g., application of glyphosate and thereby reduce the potential Ultra Blazer), you and your neighbor can expect to have for these waterhemp escapes.
2007 Illinois Crop Protection Technology Conference ♦ 69 Preparing for the Inevitable— A Prescription for Resistance ..... '
Dawn Nordby ■- \"* •: ■ , ■• , \ s " $\N _ \ %S . .. •:■ , ' *s % /
little more than ten years have passed since the Another tactic is crop rotation, ideally with the inclu commercialization of Roundup Ready soybeans sion of a crop other than corn or soybeans and different and the Monsanto claims that the inactivity of herbicides used for each crop. The markets and yield glyphosateA in the soil, the maintenance of a gene pool with tend to dictate the decision of which crop goes in the glyphosate-susceptible traits, and the unique and novel next year. The Midwest is dominated by a corn-soybean characteristics of glyphosate (combined with more than rotation with emphasis on one trait. More than 85% of 20 years of glyphosate use) had not created a resistant the soybeans are currently glyphosate resistant, with plant (Bradshaw et ah 1997). The times have changed, predictions that more than 50% of the corn planted in however, and we know for sure that Mother Nature will Illinois in 2007 will be glyphosate resistant. always find a way. Last I checked, a bag of Roundup Ready corn did not Since the beginning of chemical control for weeds, state that only glyphosate can be applied to this crop, and researchers from both industry and academia have been the same goes for soybeans. The grower and chemical presenting their cases and arguing about how to prevent dealer make the choice of which herbicide(s) are used. We herbicide resistance. Pages could be filled with the numer can look to our east (Indiana, Ohio, Delaware) and west ous suggestions on how to prevent resistance, but there (Missouri) to the locations where glyphosate-resistant is really only one: never use the herbicide. We have obvi horseweed and waterhemp first occurred in continuous ously surpassed that mark on the path toward resistance, Roundup Ready soybeans. The rotation of continuous yet we still have a few other tactics that remain. These glyphosate-resistant crops is no different. tactics can do little to prevent resistance; they can only On the other hand, the use of glyphosate-resistant crops aid in slowing the spread of herbicide resistance. has made for some clean fields over the past decade, but The use of soil-applied herbicides is a highly touted tool those times may be on the way out. The number of weed for slowing resistance; however, the number of acres on escapes following postemergence glyphosate applications which these herbicides have been used has decreased seems to be on the rise. Debates about the causes of drastically since the introduction of glyphosate-resistant these escapes will continue. Nonetheless, tillage is not crops. Preemergence herbicides use a different site of being used in most cases to clean up these fields, and a action (SOA) than glyphosate, provide residual control, third (or fourth) pass with glyphosate at a higher rate and decrease weed density prior to the postemergence does not always provide control. Gone are the days of herbicide application. The use of total postemergence cultivation— or are they? herbicide programs with no soil activity does the exact Management of glyphosate resistance varies from grower opposite; therefore, we increase our chances of develop to grower. Some implement many of these “slow down” ing resistance. tactics in hopes of keeping glyphosate around for a few
70 ♦ 2007 Illinois Crop Protection Technology Conference more years, while others plant glyphosate-resistant corn application timing and broad-spectrum weed control have and soybeans and use glyphosate exclusively. The devel been somewhat overshadowed by crop yield loss caused opment of glyphosate-resistant horseweed (marestail) by delayed application timing and the increased frequency in this state may change the mind set of these growers. of inconsistent weed control. And, with that, the search Resistant weeds do not know held boundaries. Take, for for the “silver bullet” of weed control will continue. example, 100,000 seeds from a single glyphosate-resistant horseweed plant blowing over several miles. Only then References may we start thinking about what our neighbors are doing Bradshaw, L.D., S.R. Padgette, S.L. Kimball, and B.H. Wells. to manage their weeds. Well, that is the case now. N o one 1997. Perspectives on glyphosate resistance. W eed Technology is exempt form this occurring on his or her farm. 11:189-198.
Knowing all this, it might be time to demote glyphosate Robert, S„ and U. Baumann. 1998. Resistance to the herbicide from its status as a completely safe, fix-all herbicide glyphosate. N a tu r e 395:2526. (Robert and Baumann 1998). The initial benefits of wide
2007 Illinois Crop Protection Technology Conference ♦ 71 Soybean Aphid Management: What Works and ...... What Doesn’t . . Matt O’Neal Kevin Johnson, and Nicholas Schmidt
he year-to-year and within- TABLE i • Insecticide pTogTam targeting early season populations of season variability of soybean bean leaf beetles. aphid make soybean aphid a Targeted bean leaf beetles T difficult pest to predict and manage.Treatment Rate1 generation/population The current recommendation (Rice et Control N/A al. 2005) is for soybean growers to scout their soybean fields during the growing Thiamethoxam 50 g per 100 kg Overwintering season and use an economic threshold Thiamethoxam + 50 g per 100 kg + Overwintering + first to determine the need for a foliar insec lambda- cyhalothr in 3.2 fl oz ticide. Given the recent registration of Lambda- cyhalothr in 2.5 fl oz Overwintering seed-applied insecticides, such as imi- dacloprid (Gaucho) and thiamethoxam Lambda-cyhalothrin 3.2 fl oz First (Cruiser), for early-season pests such as Lambda-cyhalothrin + 2.5 fl oz + Overwintering + first bean leaf beetles, growers may expect lambda-cyhalothrin 3.2 fl oz these products to provide protection 1 Seed treatment rates are given as grams formulated product per 100 kilogram seed. Foliar treat against soybean aphids. In this summary, ment rates are given as fluid ounces formulated product per acre. Foliar-applied insecticide was we report evaluations of seed treat lambda-cyhalothrin (Warrior ISC, Syngenta Crop Protection, Greensboro, NC), and the seed ments in comparison with the current recommendation. Please note that this summary was written before the 2006 yield data were collected; a more complete summary will populations, at three locations across Iowa (Floyd, Story, be reported during the conference. and Lucas counties; Figure 1). These treatments include seed treatments and foliar insecticides applied to over Do Seed Treatments Prevent Soybean wintering densities and the first generation of the bean Aphid Outbreaks? leaf beetle (Table 2), In Iowa, the management of insect pests in soybeans has Soybean Aphid Abundance been complicated by the arrival of the invasive soybean aphid and a recent trend of increasing bean leaf beetle In 2004 and 2005, soybean aphids arrived the first week of populations leading to economic outbreaks. Several July in all sites but Floyd County in 2004, where soybean insecticide programs (Table 1) designed to reduce aphids did not arrive until the first week of August. populations of both the overwintering population and Moreover, in 2005, soybean aphids reached densities first-generation of bean leaf beetle were evaluated during over the economic threshold of 250 aphids per plant 2004,2005, and 2006 for their impacts on soybean aphid (O’Neal 2005), in contrast to 2004, when densities did
7* ♦ 2007 Illinois Crop Protection Technology Conference The seasonal exposure of soybean to “cumulative aphid days’ was calculated based on the number of aphids counted per plant on each sampling date. Exposure of soybean plants to soybean aphids between two sampling dates (the “aphid days”) was calculated with the follow' ing equation:
where x is the mean number of aphids on sample day i, x._1 is the mean number of aphids on the previous sample day and t is the number of days between samples t—1 and i. Summing the aphid days accumulated during the growing season (cumulative aphid days) provides a FIGURE i • Experimental locations fTom north to south: measure of the seasonal aphid exposure that a soybean Floyd County, Story County, Lucas County. plant experienced (E. Hodgson, unpublished data). Cumulative aphid days are reported as season-long totals for all experiments. not exceed 100 aphids per plant at the two sites (Figure 2). In 2004, aphids peaked at 64 and 7 aphids per plant Results at Story and Floyd counties, respectively. In contrast, In 2005, there was little overlap of either the overwinter densities at 2005 study sites ranged from 313,1,082, and ing population or the first generation of bean leaf beetle 87 aphids per plant at Story, Floyd, and Lucas counties, with soybean aphids because aphid densities did not reach respectively. Because densities of soybean aphids were economic levels until early August (Figure 2). During so low in 2004 and there was no impact from any of the 2005, insecticides that were used against the overwinter treatments on soybean aphid densities or soybean yield, ing population or the first generation of bean leaf beetle we do not report those data. did not prevent economic populations of soybean aphids or consistently reduce densities compared with control Estimation of Soybean Aphids Densities treatments. Interestingly, the greatest densities of soybean Densities of soybean aphids (wingless adults, winged aphids occurred when a low rate of lambda-cyhalothrin adults, and nymphs) were estimated weekly on consecu (178 mL/ha) was applied to the overwintering popula tive plants within each plot. In 2004, soybean aphids tion of bean leaf beetles (Table 3). Although there were were counted on 10 consecutive plants for the entire differences in soybean exposure to soybean aphid in 2005, season. In 2005, the number of consecutive plants on there were no differences in yield (Figure 3). which soybean aphids were counted ranged from 5 to 20, with the number TABLE 2 • Dates of insecticide application program targeting early of plants determined by the percentage season populations of bean leaf beetles. that were infested with aphids during the previous sampling date. When 0% Foliar insecticide application date to 80% of plants were infested with Overwintering First soybean aphids, soybean aphids were Year County Planting date population generation counted on 20 plants. When 81% to 2004 Floyd May 3 May 19 July 8 99% of plants were infested, aphids on Story April 28 May 20 July 4 10 plants were counted. If all plants were infested, soybean aphids on only 2005 Floyd May 22 June 1 June 22 5 plants were counted. Story May 23 June 7 June 21 Lucas May 5 June 2 June 23
2007 Illinois Crop Protection Technology Conference ♦ 73 following: (1) reduces pesticide risks to human health; (2) reduces pesticide risks to nontarget organisms; (3) reduces the potential for contamination of valued, envi ronmental resources; or (4) broadens adoption of IPM or makes it more effective” (EPA 1998), There are two classes (neonicotinoids and pymetro2;ines) of insecticides that are lethal to soybean aphids and may be considered reduced risk, Neonicotinoid insecticides may be considered reduced risk due to their mode of exposure as a plant systemic insecticide. Pymetrozine, although not labeled for use in soybean, is a plant sys FIGURE 2 • Mean soybean aphids + standard erroT of temic insecticide with a specific mode of action (targeting mean of all locations in Iowa by yeat. the cibarial pump) that has been shown to have limited impacts on beneficial insects, including aphid predators (Harrewijn and Kayser 1997; Sechser et al. 2002; Torres The Importance of Treatment Timing for et al. 2003). It is not known what the impact of putative Soybean Aphid Management (imidacloprid) and expected (pymetrozine) reduced-risk, The majority of foliar insecticides labeled for use against foliar-based insecticides may have on the natural enemy soybean aphids in North America are organophosphates complex of soybean aphids. and pyrethroids. These insecticides are toxic to a wide We evaluated whether insecticides applied within an IPM range of insects (referred to as "broad spectrum"), includ framework (based on scouting and use of an economic ing pests and beneficial species alike, such as ladybird threshold) would provide greater yield protection than beetles. Reduced-risk insecticides may eliminate the nega use of preventive seed treatments (Table 4). In 2005 tive impact of insecticides on the predators of soybean (Floyd County) and 2006, we conducted experiments aphids. The loss of these predators may help explain why to address this question. The experiment included six applications of a foliar insecticide in June may result in treatments (including control) that compared preventive greater aphid densities than observed in untreated plots seed treatments to foliar insecticide treatments applied (Table 3). when densities of soybean aphids reached 250 aphids per The EPA defines a reduced-risk pesticide as one that “may plant. Foliar insecticides lambda-cyhalothrin, pymetrozine reasonably be expected to accomplish one or more of the (Fulfill) and imidacloprid (Trimax) were compared with seed treatments, thiamethoxam at 50 g per 100 kg seed and 100 g per 100 kg seed, and imidacloprid TABLE 3 • Peak populations of soybean aphids in during 2005 bean leaf beetle experiment. (Gaucho) at 62.5 g per 100 kg seed (see Table Peak population1at each county ± SEM Targeted bean leaf beetle 4 for rates and manu Treatment generation/population Floyd Story Lucas facturer information). Imidacloprid is com Control Overwintering 507 ± 81 281 ± 82 87 ± 14 mercially available as Thiamethoxam Overwintering 758 ± 204 302 ± 61 46 ± 7 both a seed treatment Thiamethoxam + Overwintering 828 ± 270 233 ± 62 54 ± 11 (Gaucho) and a foliar lambda-cyhalothrin First insecticide (Trimax, expected commercial Lambda-cyhalothrin Overwintering 1082 ± 275 245 ± 40 65 ± 7 release in spring 2007), Lambda-cyhalothrin First 485 ± 148 312 ± 56 56 ± 8 The two imidacloprid Lambda-cyhalothrin + Overwintering 421± 67 313 ± 93 54 ± 9 treatments allowed for lambda-cyhalothrin First a direct comparison of an insecticide applied as 1 Peak population occurred on August 25, 29, and 18 for Floyd, Story, and Lucas counties, respectively. a preventive seed treat-
74 ♦ 2007 Illinois Crop Protection Technology Conference ment and also as a foliar insecticide. Thiamethoxam and The use of pymetrozine was included to address a sub lambda-cyhalothrin are both commercially available to objective in the insecticide-timing experiment. Pyme growers for soybean aphid control in soybeans at the trozine has a Homopteran-selective mode of action that rates used. Pymetrozine is not labeled for either use in reduces the impact on the beneficial insect community soybean. (Sechser et al. 2002; Torres et al. 2003; Banks and Stark 2004). W ith an increasing body of research suggesting that predatory insects are capable of significantly reduc ing soybean aphid densities, there is an increasing level of interest in diminishing the negative impact of broad- spectrum insecticides on the predatory insect community (Fox et al. 2004, 2005; Rutledge et al. 2004; Rutledge and O’Neal 2005; Mignault et al. 2006). In 2005, we evaluated the potential reduction in flaring of soybean aphid densities when using a more specific insecticide, pymetrozine. Treatments were arranged in a randomized complete block design with six replications. Plots measured 5 by 31 meters, and were established using conventional produc tion practices. Soybeans (variety N K S24-K4 RR) were planted in 76-centimeter rows at a population of456,000 seeds per hectare (190,000 seeds per acre) using a no-till planter on May 22. Foliar insecticides were applied with a backpack sprayer using volumes of 237 liters per hectare (20 GPA) at a pressure of 274 KPA (40 psi). Insecticides applied on August 2, 2005, had a signifi cant impact on plant exposure levels to soybean aphids. Soybean aphid densities averaged 211 ± 48 (mean number of soybean aphids in nonseed-treated plots) per plant (across all nonseed treatments) at the time of the foliar insecticide application (August 2). However, soybean aphid densities quickly surpassed the economic threshold of 250 soybean aphids per plant in the control (266 ± 54 soybean aphids per plant) by August 4. In 2005, populations peaked at 1,331 ± 323 soybean aphids per plant on August 25 in the insecticide timing experiment in Floyd County. In 2005, the soybean aphid infestation significantly affected yield when soybeans FIGURE 3 • 2005 yield foT the multi-pest management at Floyd County (a), Story County (b), and Lucas were left untreated (Figure 2). The foliar insecticide County (c). lambda-cyhalothrin provided the greatest reduction in soybean aphid exposure (97.5%) and the greatest level Thiamethoxam was applied at planting, and lambda-cyhalothrin of yield protection (13% above the control; Figure 4). treatments were applied based on the emergence of the overwin The seed treatment imidacloprid provided the lowest tering first, or both generations of bean leaf beetles. Dates varied across locations due to timing of bean leaf beetle emergence. level of soybean aphid control (12% reduction) and the Foliar-applied insecticide was lambda-cyhalothrin (Warrior, lowest yield benefit compared with the control (3%). lambda-cyhalothrin, Syngenta Crop Protection, Greensboro, When compared with the untreated controls, foliar NC), and the seed treatment insecticide was thiamethoxam applications of pymetrozine and imidacloprid provided an (Cruiser, thiamethoxam, Syngenta Crop Protection, Greensboro, intermediate level of protection both in terms of soybean NC). Plots were planted on May 22 at Floyd County, on May 23 exposure to soybean aphids (89% and 86% reductions in at Story County, and on May 5 at Lucas County. exposure, respectively; Figure 4) and yield (9% and 8%
2007 Illinois Crop Protection Technology Conference ♦ 75 TABLE 4 • Products a n d T a te s foT 2005 insecticide tim ing experim ent. References
Treatment Active ingredient Rate1 Banks, J.E,, andJ.D. Stark. 2004. Aphid response to vegetation diversity and insecticide applica Control — — tions. Agriculture Ecosystems & Environment Thiamethoxam Cruiser 5 FS 50 g per 100 kg 103:595-599.
Thiamethoxam Cruiser 5 FS 100 g per 100 kg Environmental Protection Agency (EPA), Imidacloprid Gaucho 480 F 62,5 g per 100 kg 2006. Food Quality Protection Act (FQPA) of 1996. http://www.epa.gov/pesticides/regulat- Imidacloprid Trimax 4 E 1.5 fl oz ing/laws/fqpa. Pymetrozine Fulfill 50WG 2.3 oz Fox, T.B., D. A. Landis, F.F. Cardoso, and C.D. Lambda-cyhalothrin Warrior 1 SC 3.2 fl oz Difonzo. 2004. Predators suppress Aphis glycines Matsumura population growth in soybean. Envi 1 Seed treatment rates are given as grams formulated product per 100 kilogram seed. Foliar treatment rates are given as formulated product per acre. Seed treatments Cruiser (thia- ronmental E n to m o lo g y 33:608-618, methoxam, Syngenta Crop Protection, Greensboro, NC) and Gaucho (imidacloprid, Bayer Fox, T.B., D.A. Landis, F.F. Cardoso, and C.D. CropScience, Research Triangle Park, NC) were applied as a seed treatment at planting on May 22. Foliar treatments Trimax (imidacloprid, Bayer CropScience, Research Triangle Difonzo. 2005. Impact of predation on estab Park, NC), Fulfill (pymetrozine, Syngenta Crop Protection, Greensboro, NC), and Warrior lishment of the soybean aphid, Aphis glycines in (lambda-cyhalothrin, Syngenta Crop Protection, Greensboro, NC) were applied on August soybean, Glycine m ax. Biocontrol 50:545-563, 2, and aphid populations averaged 211 soybean aphids per plant at application. Harrewijn, P., and H. Kayser. 1997. Pymetrozine, a fast-acting and selective inhibitor of aphid improvement in yield, respectively; Figure 5). The foliar feeding. In-situ studies with electronic monitoring of feeding behavior. Pesticide Science 49:130-140. application of imidacloprid resulted in a greater reduc tion in soybean aphid exposure levels then when it was Mignault, M.P., M. Roy, and J. Brodeur. 2006. Soybean aphid utilized as a seed treatment (83% reduction compared predators in Quebec and the suitability of Aphis glycines as with the seed treatment of imidacloprid; Figure 4). The prey for three Coccinellidae. B io c o n tr o l 51:89—106. foliar application of imidacloprid also led to greater yield O'Neal, M.E. 2005. Insecticide use for soybean aphid control protection than when imidacloprid was applied as a seed up again in 2005. Integrated Crop M anagement Newsletter. treatment (6 % improvement; Figure 5). Iowa State University, Department of Entomology, Ames, Iowa IC-494 (21). Conclusion Rice, M.E., M.E. O ’Neal, and P. Pedersen. 2005. Soybean Aphids Foliar insecticides, when applied within an IPM frame in Iowa— 2005. Iowa State University, University Extension work (use of an economic action level of 250 soybean Publication No., SP-247. aphids per plant) reduced aphid exposure and protected Rutledge, C.E., and R.J. O’Neil. 2005. Orius insidiosus (Say) as yields more effectively than use of preventive insecticide a predator of the soybean aphid, Aphis glycines Matsumura. applications such as seed treatments, A foliar formula Biological Control 33:56—64. tion of imidacloprid, applied at an economic threshold of250 soybean aphids per plant, reduced the exposure of Rutledge, C.E., R.J. O'Neil, T.B. Fox, and D.A. Landis. 2004. soybeans to aphids and resulted in a greater yield benefit Soybean aphid predators and their use in integrated pest than when it was applied as a preventive seed treatment. management. Annals of the Entomological Society of Am erica For the prevention of soybean yield loss caused by soybean 97:240-248. aphids, the use of a preventive insecticide program did not Sechser, B., B. Reber, and F. Bourgeois. 2002. Pymetrozine: provide better protection compared with a single foliar Selectivity spectrum to beneficial arthropods and fitness for insecticide application based on the use of an economic integrated pest management. Anzeigerfiir Schadlingskunde — threshold. fournal of Pest Science 75:72-77.
Torres, J.B., C.S.A. Silva-Torres, and J.V. de Oliveira. 2003. Toxicity of pymetrozine and thiamethoxam to Aphelinus gos- s y p ii and Delphastus pusillus. Pesquisa Agropecuaria Brasileira 38:459-466.
76 ♦ 2007 Illinois Crop Protection Technology Conference 30000 68 AB
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FIGURE 4 • Comparison of seed- and foliaT-applied insecticides on soybean exposure to soybean FIGURE 5 • Comparison of seed- and foliar-applied aphids based on average cumulative aphid day insecticides on soybean exposure to A. glycines based measurements at the Floyd County site in 2005. on yield (kilograms per hectare) at Floyd County in 2005. Soybean were planted, on May 22. Seed treatments Cruiser (thiamethoxam, Syngenta Crop Protection, Greensboro, NC) Soybeans were planted on May 22. Foliar treatments imidaclo and Gaucho (imidacloprid, Bayer CropS cience, Research Triangle prid (Trimax, Bayer CropScience, Research Triangle Park, NC), Park, NC) were applied as a seed treatment. Foliar treatments pymetrozine (Fulfill, pymetrozine, Syngenta Crop Protection, Trimax (imidacloprid, Bayer CropScience, Research Triangle Greensboro, NC), and Iambda-cyhalothrin (Warrior, Syngenta Park, NC), Fulfill (pymetrozine, Syngenta Crop Protection, Crop Protection, Greensboro, NC) were applied on August 2. Greensboro, NC), and Warrior (lambda-cyhalothrin, Syngenta Mean aphid populations were 211 soybean aphids per plant at Crop Protection, Greensboro, NC) were applied on August 2, the time of application. Means labeled with a unique letter were and aphid populations averaged 211 soybean aphids per plant at significantly different (P <. 0.05). the time of application. Means labeled with a unique letter were significantly different (P < 0.05).
2007 Illinois Crop Protection Technology Conference ♦ 77 Western Bean Cutworm and the Invasion of Illinois Corn: It’s Like Deja vu All Over Again
Marlin E. Rice
he western bean cutworm— a major pest of corn Description in Colorado and Nebraska—was not a pest of Illinois corn during the previous century (Steffey ESSS T et ah 1999). It was first detected in Illinois in 2004Western bean cutworm eggs are nearly round with small (Dorhout and Rice 2004) and now occurs in at least 49 ridges extending from the top to the bottom of the egg. Illinois counties. The western bean cutworm is not the Eggs are laid in tightly packed, irregularly shaped clusters first insect to successfully invade Illinois crops. During from 21 to 195 eggs (Hagen 1962). An average cluster the last 70 years, notable pest movements into the state has 52 eggs. Eggs are white when first laid and turn dark include the European corn borer in 1939 (Mason et al. purple a day or two before hatching. 1996), the western corn rootworm in 1964 (Metcalf 1983), and, more recently, the soybean aphid in 2000 Larvae and Pupae (Gray 2000). Illinois growers or crop advisors are now Newly hatched larvae are a dull orange color with black experiencing the western bean cutworm for the first time, heads and a black pronotum (hardened plate immediately but if they feel like they've been in this situation before, behind the head). They have eight to ten black spots on then maybe they can relate to Yogi Berra when he said, each body segment. Mature larvae have a broad, faint “This is like deja vu all over again.” tan stripe along the back, gray sides, no distinctive spots, The western bean cutworm, Striacosta albicosta (Lepi- and an orange head. The pronotum has two broad brown doptera: Noctuidae), is native to North America. It was stripes. The brown stripes on the pronotum are a good first reported as a pest of Colorado pinto beans in 1915. characteristic to distinguish western bean cutworms In 1935, adults were captured in western Nebraska from other corn caterpillars. Mature larvae are about (Hagen 1963) and, later, in 1954, it was identified as IV2 inches long. There are six, occasionally seven, larval a pest of corn in southern Idaho (Blickenstaff 1979). stages. Pupae are orange-brown in color, occur in the Since its discovery in the late 1880s, it has slowly and soil, and are rarely seen. steadily expanded its known distribution eastward from Arizona to Iowa (Rice 2000) and Minnesota (O’Rourke Adults and Hutchison 2000). The western bean cutworm was The adult m oth is %'inch long and a mixture of brown, known to occasionally occur in western Iowa prior to gray, and cream colors. Each forewing has a broad, 1970, but it was not until 2000 that an economically cream-colored stripe along the front edge of the wing damaging population was found in field corn. Since and two distinctive markings— a small, light-colored then, it has become an annual economic pest in western circular spot just behind and halfway along the stripe, and central regions of the state. In 2004, western bean and a buff-colored, boomerang-shaped spot near the cutworms were collected in pheromone traps for the first end of the stripe. The hindwings are light tan with no time in Illinois and Missouri. distinct pattern.
78 ♦ 2007 Illinois Crop Protection Technology Conference Life History in Corn corn, the larvae penetrate the flag leaf and feed on pollen in In western Iowa, adult flight begins in late June, peaks the developing tassel. In tassel- in mid- to late July, and ends during mid-August (Table stage corn, larvae feed on shed 1), The female emits a mating pheromone that attracts pollen, leaf tissue, and silks and males. One to five days after mating, female moths begin eventually move to the kernels. laying their eggs on the upper surface of the topmost corn Extensive feeding on the silks leaves, especially on the flag leaf. Moths are most attracted during pollination may result to cornfields with tassels just beginning to emerge for in incomplete kernel set. egg laying. Females average 407 eggs laid during their brief lifetime. Eggs hatch in 5 to 7 days. Newly hatched The corn ear is the primary larvae feed on the tassel, corn pollen, tissue behind the feeding site for larvae. Larvae leaf sheaths, and silks The fourth and fifth instars cut enter the ear by chewing entrance holes through the husks and feed on the devel through the husk or the silks oping kernels (Hagen 1962). Each of the first five larval (Hagen 1962), Unlike corn stages takes about 5 to 6 days to develop, with the sixth earworms, which restrict most and seventh instars averaging 7 and 10 days, respectively. of their feeding to the ear tip, Unlike corn earworms, western bean cutworms are not western bean cutworms feed on cannibalistic, so several larvae may feed in the same ear. developing kernels in the ear Six larvae per ear have been found in Iowa and 20 larvae tip, middle of the ear, and ear FIGURE 1 • Corn per ear have been reported from Nebraska (Seymour et butt (Figure 1). This injury to ear damaged by al, 2004). After larvae finish feeding, they chew through developing kernels can result in single western bean the cornhusk, crawl to the ground, and form a chamber constricted and deformed ears, cutworm laTva. 3 to 8 inches deep in the soil. Here the prepupal stage particularly when larvae feed on overwinters. Pupation occurs during late May in Nebraska milk-stage kernels. Yield losses from one larva per corn (Hagen 1962). Adults begin to emerge in early summer. plant at dent stage were estimated at 3.7 bushels per acre There is one generation a year. in Nebraska (Seymour et al. 2004), while ears with single larvae in Iowa showed 4,1% to 10.9% yield loss per ear Soil type and moisture in Nebraska have influenced during 2006. In Colorado, yield reductions of 30% to 40% western bean cutworm populations. Sandy soils tended have been noted from heavily infested ears. In addition to to have larger populations compared to clay soils. Soil this loss of grain, ear molds may develop on the kernels, moisture, from either rainfall or irrigation, is necessary further reducing the yield quality at harvest. for adult emergence from their pupal cells and can be a limiting population factor, especially in clay soils. Movement Across the Midwest Damage to Corn Prior to 2000, the western bean cutworm was considered to be extremely rare in Iowa, and economic damage (i.e., Newly hatched larvae feed in one of two places, depend losses exceeding the economic threshold) had never been ing on the stage of corn development. In pretassel-stage reported. The first significant damage was observed in 2000 in a cornfield at Holstein (Rice TABLE i • Four-year blacklight captures of western bean cutworm 2000), This western Iowa field had adults in Woodbury County, Iowa, 2002-2005. approximately 95% of the ears heavily damaged. Two years later, larvae or their Western bean cutworm adults damage could be found in most western Year First capture Peak capture Last capture Total Iowa counties, and adult moths were 2002 June 28 July 13 August 11 12,739 being collected in blacklight traps in central Iowa. In 2004, pheromone traps 2003 July 10 August 1 August 17 244 were placed throughout eastern Iowa, 2004 July 5 July 23 August 10 531 including counties bordering the Missis 2005 June 28 July 13 August 10 1,328 sippi River, Adult moths were collected in every trap placed in eastern Iowa,
2007 Illinois Crop Protection Technology Conference ♦ 79 and the insect was assumed to occur in every Iowa county. Pheromone traps also were placed for a single night in July 2004 in north' eastern Missouri and west central Illinois coun' ties near Iowa. W estern bean FIGURE 4 • Ohio. cutworm adults were trapped in FIGURE 3 • Indiana. Warren County, Illinois, and Har FIGURE 2 • Captures of western bean cutwonn rison and Putnam ing 102 adults (Figure 3). Surprisingly, adults also were counties in Mis adults in pheromone traps, Illinois, 2006. reported to be trapped in western Ohio in Fulton, Shelby, souri (Dorhout and Van Wert counties (Figure 4). The Ohio captures and Rice 2004). probably represent the most easterly distribution of this These captures were the first documented occurrence of insect in the Corn Belt because no moths were reported this insect in these two states and represented a significant from traps in Clark, Crawford, Franklin, Licking, Pike, southeastern movement of the insect from its previously Wayne, and Wood counties. known distribution. The following year, pheromone traps were placed through Scouting out northern Illinois to monitor what was believed to Scouting is a primary management tactic for this insect, be a continuing range expansion of this insect. But in and it can be initiated by using either degree days or trap Illinois, the eastern limits of the distribution could not catches. Degree days (base 50°F) for 25%, 50%, and 75% be defined—traps captured moths on the Indiana state adult emergence are 1,319,1,422, and 1,536, respectively line. The trapping effort was then expanded eastward (Ahmad 1979). Adult populations also can be monitored in 2006, and, in cooperation with extension entomolo using a blacklight trap or a commercial brand (i.e., Scentry) gists and seed companies, pheromone traps were placed western bean cutworm pheromone, A common trapping throughout northern Indiana and central Ohio. procedure is to cut out windows on the upper half of a Reports of trap captures in 2006 indicated that the plastic 1-gallon milk jug. The pheromone is suspended five Illinois counties with the highest populations were inside the milk jug. The jug is filled with a 4:1 mixture Whiteside, Stephenson, Winnebago, Bureau, and Ogle, of soapy water and antifreeze that kills and preserves respectively (Figure 2) (Iowa State University 2006). The any captured specimens. The trap can then be placed on potential for economic damage was probably the greatest a post 3 to 4 feet high near a cornfield. in these fields during 2006, but traps do not necessarily Start scouting for western bean cutworm eggs in corn reflect the populations throughout the county, so eco when moths are first captured (Seymour et al. 2004) or nomic damage could have occurred in some counties at 25% predicted adult emergence. Peak adult capture, with low trap captures. Additionally, trap capture data and probably egg laying, occurs about 2 to 3 weeks after are not always good indicators of economic damage in the first adult capture (Table 1). Inspect the upper three the field. to four leaves on 20 consecutive plants at five locations. The western bean cutworm continued its march across Flybrids in different stages of development or different Illinois to the east. Moths were trapped in 10 of 12 leaf characteristics (upright vs. open) should be scouted Indiana counties, with a Newton County trap captur- separately because adult moths may be more attracted
80 ♦ 2007 Illinois Crop Protection Technology Conference TABLE 2 • Economic injury levels (eggs peT plant) foT emerged but before larvae enter the silks. If the eggs have western bean cutworm in dent stage corn.1 not hatched and plants have tasseled, time the insecticide to when most of the eggs are expected to hatch. Eggs that Control costs ($/A) are dark purple will hatch within a day. ($/bu) $8 $10 $12 $14 $16 If an insecticide application is needed, cornfields should 41 57 65 $2.00 33 49 be checked for the presence of spider mite colonies. If $2.25 29 37 44 51 57 mites are found, select a product that does not stimulate $2.50 26 33 40 46 52 mite reproduction. Products that contain permethrin (Pounce, Ambush) or esfenvalerate (Asana) have been 1 Modified from Appel et al. 1993. associated with increased mite reproduction. Other products labeled for western bean cutworm control on corn include Capture 2EC, Lorsban 4E, Penncap-M, to one hybrid than the other. A nominal threshold rec Sevin XLR Plus, and Warrior 1EC. ommended by the University of Nebraska is 8% of the plants with eggs or young larvae found on the flag leaf or Transgenic Corn in the tassel (Seymour et al. 2004). A simple economic threshold that considers the value of corn and the cost Transgenic corn is available with control against several of the insecticide application is shown in Table 2. The species of caterpillars (Table 3). values in this table, based on research conducted at the In 2006, corn hybrids were evaluated at three locations in University of Nebraska, assume 3.3% survival of the eggs. northwestern Iowa for performance against western bean O f these two thresholds, the 8% infested plant threshold cutworm. Each ear was divided into four equal quadrates is more commonly used, but the relative accuracy of one (looking down from the tip of the ear), and the length method over the other is unknown. of damage was measured in centimeters, with damage from all quadrates combined per ear, A minimum of 20 Management ears per hybrid were examined at each location. Field Insecticides observations indicate that Herculex I or Herculex Xtra provided the best level of protection against western Timing of an insecticide application is critical. If the tassel bean cutworm (Table 4), and it was consistently better has not emerged when the larvae hatch, they will move than YieldGard Corn Borer hybrids in providing protec into the whorl and feed on the developing pollen grains tion (Tables 4-6). Hercules does not provide complete in the tassel. As the tassel emerges, the larvae will move protection against western bean cutworm damage, but down the plant to the green silks and then into the silk the amount of damage was very small when compared to channel to feed on the developing ear. Once the larvae damage on YieldGard ears at all locations and across all reach the ear tip and enter the silks, effective control with hybrids (Table 6), Based on these data, only corn with an insecticide is nearly impossible. Seymour et al. (2004) the Bt protein CrylF offered in Herculex I or Herculex state that if the eggs have hatched, insecticide applica Xtra hybrids have the potential to control western bean tions should be made after 95% of the plant tassels have cutworms.
TABLE 3 • Pest control spectrum of Bt corn for Lepidoptera1.
Western bean European Corn Fall Black Product Event/gene cutworm corn borer earworm Army worm army worm cutworm Herculex2 TC1507CrylF Control Control Suppression Not labeled Control Control
YieldGard Mon810CrylAb Not labeled Control Suppression Not labeled Suppression Not labeled YieldGard Btll CrylAb Not labeled Control Suppression Not labeled Suppression Not labeled
1 As stated by seed industry literature. 2 Includes Herculex I and Herculex Xtra.
2007 Illinois Crop Protection Technology Conference ♦ 8l Table 4. Western bean cutworm damage to HeTculex 1t Herculex and Rice, 2006), may be a partial explana Xtra, and YieldGard Corn Borer hybrids at three Iowa locations, tion for the increased damage to corn in 2006. the Midwest and range expansion of the Mean cm western bean cutworm. Location Company Hybrid Trait damage/ear1,2 The Future Laurens Mycogen 2J454 — 5.60 a Northrup King N51-T8 YG-CB 4.88 ab The western bean cutworm appears to Mycogen 2D545 — 4.73 ab be firmly established as a pest of Illinois Northrup King N46-J7 YG-CB 4.55 ab field corn. Its movement into Indiana and Mycogen 2E522 — 3.93 abc Ohio was unexpected yet not surprising, Northrup King N51-V9 YG-CB 3.70 abc considering the adaptive ability of many Mycogen 2J525 — 3.03 bed Northrup King N36-R6 YG-CB 3.00 bed pest insects (i.e,, western corn rootworm, Northrup King N53-U1 YG-CB 2.45 cd European corn borer, soybean aphid) to Garst 8693 YG-CB 2.38 cd expand their range. W hether the western Garst 8880 YG-CB 1.45 de bean cutworm will become a significant Garst 8534 YG-CB 1.38 de pest in Illinois, Indiana, or Ohio can only Mycogen 2A498 — 1.38 de be answered in the future. However, the Mycogen 2G677 HX-X 0.10 e damage potential represented by this Mycogen 2R570 HX-I 0.03 e species strongly suggests that it should not Mallard Mycogen 2K541 YG-CB 4.08 a be ignored, nor should fear of economic Mycogen 2D545 — 3.08 a damage be an immediate reason to invest Mycogen 2E633 HX-I 1.35 b in increased acres of transgenic Bt corn. Mycogen 2D555 HX-I 0.43 be Fortunately, corn growers have a primary Mycogen 2R570 HX-I 0.35 be Mycogen 2E526 HX-X 0.10 c tool at their disposal to manage the western Mycogen 2J527 HX-I 0.05 c bean cutworm should it reach economically damaging levels—scouting combined with Rembrandt Mycogen 2K541 YG-CB 5.00 a a properly timed insecticide. If the western Mycogen 2D545 — 4.53 a bean cutworm does become an established, Mycogen 2E522 — 4.30 a Mycogen 2J665 - 1.05 b economically damaging pest in the state, Mycogen 2E633 HX-I 0.20 b then growers should consider an addi Mycogen 2D555 HX-I 0.00 b tional pest management tool—planting Mycogen 2D673 HX-I 0.00 b transgenic Herculex I or Herculex Xtra Mycogen 2P722 HX-I 0.00 b corn hybrids. Mycogen 2R570 HX-I 0.00 b
1 Means at the same location and followed by the same letter are not statistically significant Acknowledgments by A N O V A , P = 0.05. The pheromone trapping was coordinated 2 n — 20 ears per hybrid except Mallard, Mycogen 2K541, n = 60 ears. by Rich Pope and Carol Pilcher (Iowa State University) and supported by Kevin An interesting find in two of the three locations was that Steffey and Mike Gray (University of Illinois at Urbana- YieldGard Corn Borer hybrids had more kernel damage Champaign), Christian Krupke (Purdue University), than the untreated check hybrids (Table 5). Data are Ron Hammond (The Ohio State University), and Sara still being analyzed as of this writing, but experiments and Ben Linn (Woodbury County, Iowa). Dave Dorhout at Iowa State University suggest that a YieldGard Corn assisted with the collection of field data. Their participa Borer hybrid changes the ratio, or proportion, of cat tion in this project is greatly appreciated. erpillar species that attack YieldGard hybrids, thereby indirectly favoring the western bean cutworm and allow References ing it to cause more damage in a YieldGard hybrid than Ahmad, T.R. 1979. Comparison of heat unit accumulation in a near-isogenic corn hybrid without the Bt protein. methods for predicting European corn borer and western bean This phenomenon, known as pest replacement (Pedigo
82 ♦ 2007 Illinois Crop Protection Technology Conference TABLE 5 • Western bean cutworm damage (summarized by TABLE 6 • Composite performance of all location) to Herculex1 and YieldGard Corn Borer hybrids, Iowa, Herculex1 and YieldGaTd Corn Borer hybrids at 2006. three Iowa locations, 2006.
Mean ± S.E. cm Ears Mean cm Location Trait Ears examined damage/ear2 Trait examined damage/ear2
Laurens Herculex I n = 40 0.06 ± 0.54 b Herculex I n = 240 0.22 ± 0.19 b YieldGard CB n = 160 2.97 + 0.27 a YieldGard GB n — 240 3.42 + 0,19 a Check n = 100 3.73 ± 0.34 a Check n — 180 3.51 + 0.22 a Mallard Herculex 1 n = 100 0.46 ± 0.20 c YieldGard CB n = 60 4.08 + 0.44 a 1 Herculex I and Herculex Xtra ratings combined. Check n — 20 3.08 ± 0.34 b 2 Means followed by the same letter are not statistically significant Rembrandt Herculex I n = 100 0.04 ± 0.26 c by ANOVA, P = 0.05. YieldGard CB n = 2 0 5.00 ± 0,57 a Check n = 60 3.29 ± 0.33 b
1 Herculex I and Herculex Xtra ratings combined. 2 Means at the same location and followed by the same letter are not statistically significant by ANOVA, P = 0.05.
cutworm moth flights. M.S, thesis, University of Nebraska. Mason, C.E., M.E. Rice, D.D. Calvin, J.W. Van Duyn, W.B. 47 pp. Showers, W.D. Hutchison, J.F. Witkowski, R.A. Higgins, D.W. Onstad, and G,P. Dively. 1996, European Corn Borer Appel, L.L., R.J. Wright, and J.B. Campbell. 1993. Economic Ecology and M anagement, North Central Regional Extension, injury levels for western bean cutworm, Loxagrotis albicosta Publication No. 327, Iowa State University. (Smith) (Lepidoptera: Noctuidae), eggs and larvae in field corn. Journal of the Kansas Entomological Society 66:434-438. Metcalf, R.L. 1983. Implications and prognosis of resistance to insecticides, pp, 703-733. In Georghiou, G.P., and T, Saito Blickenstaff, C.C. 1979. H istory and Biology of the W estern Bean (eds). Pest Resistance to Pesticides. Plenum Press, New York. Cutworm in Southern Idaho, 1942-1977. University of Idaho Agricultural Experiment Station Bulletin 592. 23 pp. O'Rourke, P.K., and W.D. Hutchison. 2000. First report of the western bean cutworm, Richia albicosta (Smith) (Lepidoptera: Dorhout, D.L., and M.E. Rice. 2004. First report of western bean Noctuidae), in Minnesota corn. Journal of Agricultural and cutworm, Richia albicosta (Noctuidae), in Illinois and Missouri. Urban Entomology 17:213—217. Crop Management (http://www.plantmanagementnetwork, org/pub/cm/brief/2004/cutworm). Pedigo, L. P., and M. E. Rice. 2006. Entomology and Pest M an agement, 5th edition. Pearson Prentice Hall. Upper Saddle Gray, M.E. 2000. Special report: New soybean insect pest dis River, NJ. covered in northern Illinois, Wisconsin, and Michigan. P e st M anagement and Crop Development Bulletin, No. 20. University Rice, M.E. 2000. Western Bean Cutworm Hits Northwest Iowa. of Illinois Extension, Champaign-Urbana. (http://www.ipm. Integrated Crop Management IC-484 (22:163). Iowa State uiuc.edu/bulletin/pastpest/articles/200020h.html). University Extension, Ames, IA (http://www.ipm,iastate. edu/ipm/icm/2000/9-18-2000/wbcw.html). Hagen, A.F, 1962. The biology and control of the western bean cutworm in dent corn in Nebraska. Journal of Economic Ento Seymour, R.C., G.L. Hein, R.J. Wright, and J.B. Campbell. 2004. m o lo g y 55:628-631. Western Bean Cutworm in Corn and D ry Beans, University of Nebraska (http://www,ianrpubs.unl.edu/sendlt/gl359. Hagen, A.F, 1963. Evaluation of populations and control of the pdf)- ' . western bean cutworm in field beans in Nebraska. J o u r n a l o f Economic Entomology 56:222—224. Steffey, K.L., M.E. Rice, J. All, D. A. Andow, M.E. Gray, and J.W Van Duyn (eds). 1999, Handbook of Corn Insects. Entomologi Iowa State University, 2006. Western Bean Cutworm M onitoring cal Society of America, Lanham, MD. N e tw o r k (http://www.ent.iastate.edu/trap/westernbeancut- worm/isite).
2007 Illinois Crop Protection Technology Conference ♦ 83 Transgenic Corn Rootworm Hybrids: Assessing Performance in a Variant .
ill!Western |p; !||! iiiiiil Corn II!!! !§!§ Rootworm §§ l|l|l|||lllil|l Arena |l i|ii ||§|fi |||p!ilil!i-?:':' Michael E. Gray, Kevin L, Steffey, Ronald E. Estes, and Jared B. Schroeder
he 2006 growing season proved to be another The discussion and information contained within this challenging year for producers throughout Illi paper focus on root rating data and do not describe nois as they attempted to limit yield losses in yield results. Accurately predicting corn yield with root T their cornfields due to impressive root pruning andrating silk data has never been very successful due to the clipping activities by western corn rootworms. Yield loss tangle of interactions among corn hybrids with respect attributed to corn rootworm damage is generally most to root regeneration characteristics, level of root injury, extreme in drought years. Precipitation across our three and environmental conditions, particularly precipitation test sites (DeKalb, Monmouth, and Urbana) was most patterns (Gray and Steffey 1998). In addition, comparing generous in Urbana and least abundant in Monmouth, yields across treatments has become a bit more compli particularly for the month of July (Table 1). In Urbana, cated by the inclusion of more Bt corn rootworm hybrids the rainfall total for July was nearly 8 inches; whereas (multiple events) and their corresponding isolines in our in Monmouth, fewer than 2 inches of precipitation efficacy experiments. Although we used a trap crop system accumulated for the month. These extremes in rainfall (late-planted corn in 2005 interplanted with pumpkins) totals enable us to assess the protection performance of to ensure greater rootworm injury in our test plots, we various corn rootworm products across a broader range witnessed extreme root injury even by our trap crop of environmental conditions. standards. By using this approach, we intentionally place corn rootworm products under greater scrutiny. Although it is less common to witness root pruning as Table i • Precipitation totals (inches) for DeKalb, great as occurred in our experiments, severe root injury Monmouth, and UTbana, from April through August and lodging do occur in some producers fields each year. 2006. We believe the results from our trials enable produc ers to make more informed choices regarding product Months DeKalb Monmouth Urbana selection for corn rootworms. The root rating results for April 3.55 3.21 4.41 three of our corn rootworm product efficacy experiments May 4,01 1.47 3.06 (DeKalb, Monmouth, and Urbana) are presented in Table 2. Mean root injury values are not presented for the June 3.19 2.38 1.65 Perry location due to very low corn rootworm pressure July 2.45 1.65 7.85 at this site, including the untreated check. Despite the August 2.30 3.67 3.0 low corn rootworm injury at Perry in 2006, we intend to continue our efficacy experiments in western Illinois. TOTALS 15,5 12,38 19.97 This is primarily in response to the variant western corn rootworms expanding range.
84 ♦ 2007 Illinois Crop Protection Technology Conference TABLE 2 • Root Tarings1 and percentage consistency1 foT corn rootworm products, DeKalb, Monmouth, and UTbana, University of Illinois, 2006.
DeKalb4 Monmouth5 Urbana6 DeKalb4 Percentage Monmouth5 Percentage Urbana6 Percentage Products Rate2’3 Placement Root Rating7 Consistency Root Rating7 Consistency Root Rating7 Consistency
Aztec 2.1G 6.7 oz Band 0.58 gh 85% 0.23 fg 100% 0.68 fgh 70%
Aztec 2.1G + 6.7 oz Band 0,96 efg 60% 0.20 fg 100% 0.53 gh 90% Poncho 2502
Aztec 2.1G + 6,7 oz Band 0.52 gh 80% 0.17 fg 100% 0.57 gh 95% Poncho 12509
Aztec 4.67G 3 oz Smart Box- 0.54 gh 80% 0.20 fg 100% 0.65 gh 80% Furrow
Capture LFR 8.5 fl oz/A Furrow 1.6 a-d 23% — — — — 1.5EC
Force 3G 4 oz Band 0.55 gh 85% 0.57 d 80% 1.01 e 50%
Fortress 5G 4 oz Smart Box- 0.73 fgh 65% 0.38 d-g 100% 0.55 gh 85% Furrow
Fortress 2.5G 8 oz Furrow 1.28 def 30% 0.39 def 90% 0.54 gh 95%
Lorsban 15G 8 oz Band 0.80 fgh 65% 0.47 de 95% 0.63 gh 75%
Poncho 12509 1,25 mg Seed 1.24 cde 5% 1.65 b 15% 1.97 cd 0% a.i./seed treatm ent
HxXTRA + — Transgenic 0.08 i 95% 0.24 g 95% 0.47 h 85% Poncho 2508 (Pioneer 34A18)
Untreated — 2.01 ab 0% 2.56 a 0% 2.43 abc 0% Pioneer Check (34A16) + Poncho 250s
H xR W + — Transgenic 0.22 fg 95% 0.55 gh 85% Cruiser10 (Mycogen 2G777)
HxXTRA + — Transgenic 0.40 efg 80% 0.44 h 90% Cruiser10 (Mycogen 2P788)
Untreated — 2.90 a 0% 2.94 a 0% Mycogen 2784 Check
YG RW — Transgenic 0.49 h 75% 0.39 d-g 85% 0.96 ef 35% (DeKalb 61-68) + Poncho 2508
Untreated — 2.07 ab 0% 2.98 a 0% 2.95 a 0% DeKalb Check (DK61-72)
Footnotes continued on next page
2007 Illinois Crop Protection Technology Conference ♦ 85 1 Root ratings are based on the 0 to 3 root-rating scale developed by Oleson likely hastens the potential development of resistance to et al. (2005): 0.00 = no feeding damage; 1.0 = one node (circle of roots), the neonicotinoid seed treatments. Thie performance of or the equivalent of an entire node, pruned back to within approximately 3.8 cm (1.5 inches) of the stalk (or soil line if roots originate above ground Poncho 1250 as a stand-alone corn rootworm treatment nodes); 2.0 = two complete nodes pruned; 3.0 = three or more complete was very poor, with root ratings of 1.24,1.65, and 1.97 nodes pruned (highest rating that can be given). Percentage consistency and consistency ratings of 5%, 15%, and 0% for DeKalb, is the percentage of roots with a node injury rating < 1.0. Five randomly Monmouth, and Urbana, respectively. Producers who selected root systems were dug from the second or third row of each four- continue to use this product to protect their refuge may row plot, in each of four replicates. be in for some unpleasant surprises. For several years, the 2 Rates of application for band and in-furrow placements are ounces per 1,000 feet of row. insecticidal seed treatments have not provided consistent 3 Rates of application for seed treatments are milligrams of active ingredi corn rootworm protection in our trials. ent per seed. Performance of the other granular soil insecticides varied 4 Planting date April 27,2006, into a trap crop (late-planted corn interplanted across locations. Root ratings in the Force 3G treatment with pumpkins); root evaluation date July 25, 2006; DeKalb 61-72 was the hybrid used for all soil insecticide treatments. averaged approximately % node of roots pruned in DeKalb and Monmouth; however, in Urbana, more than one 5 Planting date May 4,2006, into a trap crop (late-planted corn interplanted with pumpkins); root evaluation date July 24, 2006; DeKalb 61-72 was node of roots was destroyed by July 17, with 50% of the the hybrid used for all soil insecticide treatments. roots exceeding a root rating of 1.0. This is much greater 6 Planting date April 28,2006, into a trap crop (late-planted corn interplanted root injury than we have typically encountered in our with pumpkins); root evaluation date July 17, 2006; DeKalb 61-72 was experimental trials with Force. Root protection for both the hybrid used for all soil insecticide treatments. Mycogen treatments formulations of Fortress was poorest at the DeKalb loca were planted May 6, 2006. tion, with % of a node and 1% nodes of roots destroyed 7 Means followed by the same letter (within a column) do not differ signifi in the 5G and 2.5G formulations, respectively. The root cantly (P = 0.05, Duncan's New Multiple Range Test). protection of Fortress was much better in Monmouth 8 Poncho applied at 0.25 mg a.i./seed. and Urbana, with root ratings ranging from 0.39 to 9 Poncho applied at 1.25 mg a.i./seed. 0.63. Interestingly, another organophosphate insecticide 10 Cruiser applied at 0.25 mg a.i./seed. treatment, Lorsban 15G, had the most root injury (0.80, nearly one node destroyed) at the DeKalb location. Root protection with Lorsban at Monmouth and Urbana was Corn Rootworm Product Performance better, with root ratings of 0.47 and 0.63, respectively. Results—July Evaluations Unlike most other granular soil insecticides that offer more consistent root protection when applied in a band, The level of root injury in the untreated check (DK 61-72) Fortress generally provides more consistent root protec was 2.07,2.98, and 2.95 in our plots at DeKalb (July 25), tion when placed in-furrow, as in our experiments. Monmouth (July 24), and Urbana (July 17), respectively. These levels of root injury are extreme, particularly at Although many producers would like the flexibility to Monmouth and Urbana (three nodes of roots destroyed). use a liquid insecticide for their corn rootworm control For all soil insecticide treatments, DK 61-72 was the program, we have not witnessed consistent root protec hybrid chosen for our experiments at each study site. The tion from liquid formulations of soil insecticides. An performance of Aztec was excellent at Monmouth (driest in-furrow application of Capture LFR (1.5 EC) offered location), with very low root injury and 100% consistency poor root protection by mid-July (IV2 nodes destroyed) (100% of roots had injury < 1.0) across four treatments. at the DeKalb location. This treatment was not applied However, in DeKalb and Urbana, root pruning in the in Monmouth or Urbana. Aztec treatments was typically % node or greater. The In 2006, for the first time, we were able to compare in consistency of root protection also was reduced in DeKalb the same trials the root protection afforded by trans and Urbana, ranging from 60% to 95%. The addition of genic corn rootworm hybrids with different events from Poncho 250 or 1250 with Aztec 2.1G did not enhance Monsanto (MON 863, Cry3Bbl, YGRW), Pioneer the level of root protection against corn rootworms. The Hi-Bred International, Incorporated (DAS-59122-7, results from our trials, again, are very clear with respect Cry34Abl/Cry35Abl, HxXTRA), and Mycogen (DAS- to this point. The addition of this insecticidal seed treat 59122-7, Cry34Abl/Cry35Abl, HxRW, HxXTRA). ment with Aztec 2.1G is not a good investment and most In general, the root protection of these transgenic corn
86 ♦ 2007 Illinois Crop Protection Technology Conference rootworm hybrids was very good to excellent. The There is some circumstantial evidence in the entomo HxXTRA (Pioneer 34A18) treatment had July root logical literature (Siegfried et al. 2005) to support our ratings of 0.08, 0.24, and 0.47 in DeKalb, Monmouth, hypothesis. Field observations during the past few years and Urbana, respectively. Considering the level of root also provide some additional circumstantial evidence injury in the control, these are very acceptable levels of to support our idea. More work is clearly warranted to root protection. For this treatment (HxXTRA, Pioneer explore this hypothesis more fully. 34A18), root injury comparisons should be made with As in previous years, the YieldGard RW hybrid (DK the appropriate control, Pioneer 34A16, which was also 61-68 + Poncho 250) at the Urbana experimental site treated with Poncho 250. The HxRW (Mycogen 2G777) experienced an increase in rootworm pruning from mid- and HxXTRA (Mycogen 2P788) transgenic corn root- July (0.96) to early August (1.46). By mid-July, nearly worm treatments provided very good (% node or less one full node of roots was pruned on the YieldGard RW pruned) root protection at the Monmouth (root ratings: treatment; by early August, approximately I-V2 nodes of HxRW, 0.22; HxXTRA, 0.40) and Urbana (HxRW 0.55; roots were destroyed (Table 3), By August 8, the YieldGard HxXTRA, 0.44) locations. These root ratings should be RW treatment in Urbana had a consistency percentage compared with the appropriate control (Mycogen 2784), of 0%. This is not an acceptable level of root protection. which did not receive any insecticidal seed treatment. Due Plants are much more susceptible to lodging when one to late shipments of seed, the Mycogen Bt corn rootworm full node of roots has been pruned. Excessive lodging can treatments were not planted until May 6 at the Urbana lead to more significant physiological yield losses and can site. This is certainly much later than desired, and we increase harvest difficulties. The root protection of the should expect better root protection when planting is YieldGard RW treatment at DeKalb and Monmouth was delayed to this extent. The YieldGard RW (DK 61-68) much better, with August root ratings of 0.41 and 0.59, treatment had root ratings in July of0.49,0.39, and 0.96 respectively. The consistency percentages in August for at the DeKalb, Monmouth, and Urbana experiments, the YieldGard RW and HxXTRA (Pioneer 34A18 + respectively. These root ratings should be compared with Poncho 250) treatments were identical at DeKalb and the untreated check (DK 61-72), which did not receive Monmouth, 100% and 80%. W hy was the performance any insecticidal seed treatment. The level of root injury of the YieldGard RW treatment so compromised in (nearly one node pruned) in Urbana was much greater Urbana as compared with the other two locations? The than anticipated for mid-July. In addition, the planting August level of root injury in the untreated check (DK date for this treatment was April 28, much later than 61-72) was similar in Monmouth (2.82) and Urbana most producers hope to achieve in east central Illinois. (3.0). So, variation in corn rootworm pressure doesn’t How severe would the root injury have been if planting appear to be a satisfactory explanation. The Aztec 2.1G had occurred during the first week of April? treatment provided fair (DeKalb, 0.58 to 0,78; Urbana, 0.68 to 0.63) to very good (Monmouth, 0.23 to 0.41) Corn Rootworm Product Performance protection of roots at both root rating dates across all Results—August Evaluations three locations. The root protection offered by Poncho During the past several years, we have observed late-season 1250 was very poor by August 8 for DeKalb, Monmouth, brace root pruning on some YieldGard RW hybrids, and Urbana, at 1,42,1.72, and 2.35, respectively. especially at the Urbana location (Gray et al. 2005,2006). To a lesser extent, late-season brace root pruning also Evaluation of YieldGard Rootworm has been observed with some YieldGard RW hybrids at Transgenic Hybrids in Monmouth and the DeKalb site. At Monmouth, this phenomenon has Urbana not occurred. We have speculated previously that the In 2005, we evaluated eight YieldGard RW hybrids variant western corn rootworm may be at least partially (M ON 863) in a trial located near Urbana. We concluded responsible for these observations. Densities of the variant that some variation in root protection was present among western corn rootworm are greater in Urbana and at the transgenic hybrids we evaluated. In 2006, we expanded intermediate levels in DeKalb, and numbers are increas the trial to include ten YieldGard RW hybrids (MON ing near Monmouth. Variant western corn rootworms 863) and planted them in two locations, Monmouth and may be more aggressive root feeders and less susceptible Urbana (Tables 4 and 5). In each year of this study, we to the Bt protein expressed by YieldGard RW hybrids.
2007 Illinois Crop Protection Technology Conference ♦ 8 7
0% 0% 0% August 8 Consistency % 80% 95%
1.46 c 3,0 a Urbana5 2.35 b 0.37 d August 8 0.63 d
1.97 cd Urbana5 2.95 a 0.47 h 0.96 ef 0,68 fgh July 17 5% 0% August 8 95% 80% 80% % Consistency %
1.72 b 0.41c 0.52 c 0.59 c 2.82 a 0.05, Duncans New Multiple RangeTest). (P = (P 1.65 b 0.39 d-g Monmouth4 Monmouth4 0.23 fg 0.24 g 2.98 a July 24July August 8 0% 15% 69% 100% 100% DeKalb3 Monmouth4 Urbana5 August 8 % Consistency %
1.42 b DeKalb3 2.15 a 0.19 d 0.41 d August 8 0.78 c
1.24 cde 0.49 h 0.08 i 2.07 ab DeKalb3 0.58 gh July 25 _ Band treatment Transgenic Seed Transgenic Place ment o z 1.25 1.25 mg _ Rate2 6,7 17; second evaluation was August 8. that can be given). Percentage consistencyin each of is fourthe percentagereplicates. Means ofroots followed with by thea node same injury letter rating (within < 1.0. Fivea column)randomly do selected not rootdiffer significantly systems were dug from the second or third row ofeach four-row plot, second evaluation was August 8. within approximately 3.8 cm (1,5 inches) ofthe stalk (or soil line ifroots originate aboveground nodes); 2.0 = two complete nodes pruned; 3.0 - three or more complete nodes pruned (highest rating 25; second evaluation was August 8. Poncho applied at 0.25 mg a.i./seed. Planting date May 4, 2006, into a trap crop (late-planted corn interplanted with pumpkins). DK 61-72 was the hybrid used for all soil insecticide treatments. First root rating evaluation wasJuly 24; Rates ofapplication for band and in-furrow placements are ounces per 1,000 feet ofrow. Rates ofapplication for seed treatments are milligrams ofactive ingredient per seed. Poncho applied at 1.25 mg a.i./seed. Root ratings are based on the 0 to 3 root-rating scale developed by Oleson et al. (2005): 0.00 = no feeding damage; 1.0 = one node (circle ofroots), or the equivalent ofan entire node, pruned back to Planting date April 28, 2006, into a trap crop (late-planted corn interplanted with pumpkins). DK 61-72 was the hybrid used for all soil insecticide treatments. First root rating evaluation wasJuly Planting date April 27, 2006, into a trap crop (late-planted corn interplanted with pumpkins). DK 61-72 was the hybrid used for all soil insecticide treatments. First root rating evaluation wasJuly (DK61-72) 1 Untreated DeKalb Check (DK 61-68) + (Pioneer 34A18) 5 3 Poncho 2507 YGRW H xX T R A + Poncho 12506 a.i./seed 7 6 4 2 Products Aztec 2.1G 2006. Poncho 2507 TABLE 3 •injury Root and ratings1 percentage for fust evaluations:andTABLE second a, consistency1 Monmouth, University andofDeKalb, Illinois, Urban
88 ♦ 2007 Illinois Crop Protection Technology Conference also planted a check hybrid (non-Bt). In addition, in each 98% consistent) among those YieldGard RW hybrids that year, two transgenic YieldGard RW hybrids that failed were commercialized. By August 8, root protection across to meet Monsantos commercialization standards were most commercial YieldGard RW hybrids ranged from % included in our experiments. The genetic background to V i node of roots pruned. The range in root injury was and commercial names of all hybrids remain unknown 0.22 (hybrid C, 98% consistent) to 0.75 (hybrid K, 65% to us for both years, and treatments are simply labeled consistent). The two YieldGard RW hybrids that were with letters of the alphabet, A through K, for the 2006 not commercialized, D and F, had root ratings of 1.09 experiment. For the 2006 experiment, hybrid B served as and 1.44, respectively, by August 8. Overall, we conclude the control (nontransgenic hybrid), and hybrids D and that most commercialized YieldGard RW hybrids offered F (both YieldGard RW hybrids, M ON 863) failed to very good to excellent root protection at the Monmouth meet commercialization standards (Monsanto protocols). site. However, by August 8, hybrid K had % of a node Why did we establish a duplicate experiment near Mon of roots pruned and a consistency percentage of only mouth;? To gather more data regarding our hypothesis 65%. This level of protection is less than desirable. All concerning the variant western corn rootworms ability hybrids were planted at the Monmouth site on May 4, to inflict more root injury on YieldGard RW hybrids in 2006. Many farmers consider this planting date late by the Urbana area, we planted another trial with the same modern corn production standards. If these YieldGard hybrids near Monmouth, an area that does not support RW hybrids were planted in early to mid-April, would high densities of variant western corn rootworms, yet. the root ratings have been affected? We intend to examine this question more critically with the initiation of plant Root protection at the Monmouth site (Table 4) was ing-dates studies in 2007. excellent across the YieldGard RW hybrids as of July 24, with typical root injury of % node pruned or less. This The YieldGard RW hybrid evaluation trial located near protection occurred despite heavy pressure, as evidenced Urbana (Table 5) was planted on May 5, 2006. On July by the severity of root pruning (2.63) in the check (non- 20, root injury across the commercialized YieldGard Bt hybrid). By the third week in July, root injury ranged RW hybrids typically ranged from % to %3 node of roots from 0.06 (hybrid C, 100% consistent) to 0.30 (hybrid K, pruned. Root injury in the non-Bt check (hybrid B) was
TABLE 4 • Root ratings1’2 and percentage consistency1 foT YieldGard (MON 863) corn rootworm hybrids (A-K) evaluation trial, University of Illinois, Monmouth3, 2006.
Root Evaluation Dates A B C D E F G H I J K July 24 Ratings4 0.19 de 2.63 a 0.06 e 0.76 c 0.20 de 1.00 b 0.16 de 0.22 de 0.11 de 0.15 de 0.30 d July 24 % Consistency 100% 0% 100% 53% 90% 35% 95% 88% 100% 95% 98% August 8 Ratings4 0.34 e 2.74 a 0.22 e 1.09 c 0.42 e 1.44 b 0.38 e 0.41 e 0.23 e 0.45 e 0.75 d August 8 % Consistency 93% 0% 98% 41% 90% 18% 90% 82% 98% 83% 65%
1 Root ratings are based on the 0 to 3 root-rating scale developed by Oleson et al. (2005): 0.00 = no feeding damage; 1.0 = one node (circle of roots), or the equivalent of an entire node, pruned back to within approximately 3.8 cm (1.5 inches) of the stalk (or soil line if roots originate above ground nodes); 2.0 = two complete nodes pruned; 3.0 — three or more complete nodes pruned (highest rating that can be given). Percentage consistency is the percent age of roots with a node injury rating < 1.0. 2 Means followed by the same letter do not significantly differ within a row (P = 0.05, Duncans New Multiple Range Test). 3 All YieldGard Rootworm hybrids (M ON 863) were planted on May 4, 2006. 4 Ten randomly selected root systems were dug from the center two rows of each four-row plot (in each of four replicates) and washed and evaluated for corn rootworm larval injury.
2007 Illinois Crop Protection Technology Conference ♦ 89 TABLE 5 • Root ratings1'2 and percentage consistency1 for YieldGard (MON 863) corn rootworm hybrids (A-K) evaluation trial, University of Illinois, Urban a3, 2006.
Root Evaluation Dates A B C D E F G H I J K July 20 Ratings4 0.39 d 2.52 a 0.24 d 0.79 c 0.29 d 1.21b 0.34 d 0.36 d 0.41 d 0.14 d 0.36 d July 20 % Consistency 88% 0% 95% 48% 93% 10% 95% 88% 87% 100% 90% August 7 Ratings4 0.86 c 2.68 a 0.62 d 1.50 b 0.89 c 1.92 b 0.83 c 0.83 c 0.79 c 0.66 c 0,91c August 7 % Consistency 54% 0% 83% 10% 58% 0% 63% 65% 60% 75% 55%
1 Root ratings are based on the 0 to 3 root-rating scale developed by Oleson et al. (2005): 0.00 = no feeding damage; 1.0 = one node (circle of roots), or the equivalent of an entire node, pruned back to within approximately 3.8 cm (1.5 inches) of the stalk (or soil line if roots originate above ground nodes); 2.0 = two complete nodes pruned; 3.0 = three or more complete nodes pruned (highest rating that can be given). Percentage consistency is the percent age of roots with a node injury rating < 1.0. 2 Means followed by the same letter do not significantly differ within a row (P = 0.05, Duncans New Multiple Range Test). 3 All YieldGard Rootworm hybrids (M ON 863) were planted on May 5, 2006. 4 Ten randomly selected root systems were dug from the center two rows of each four-row plot (in each of four replicates) and washed and evaluated for corn rootworm larval injury.
2,52 (2V2 nodes of roots pruned) on July 20. This level Monmouth by the second root evaluations (August 7 and of root injury is similar to that observed in the Mon 8). The reductions in percentage consistency between these mouth YieldGard RW hybrid trial. The range in root two experiments for the various hybrids were as follows: injury among commercialized hybrids was 0.14 (hybrid hybrid A, 39%; hybrid C, 15%; hybrid D, 31%; hybrid J, 100% consistent) to 0.41 (hybrid I, 87% consistent) E, 32%; hybrid F, 18%; hybrid G, 27%; hybrid H, 17%; on July 20. Considering the level of injury in the control, hybrid I, 38%; hybrid J, 8%; and hybrid K, 10%. These this protection is quite good. By August 7, 2% weeks data would appear to support our hypothesis that the after the first root evaluations, the level of root injury variant western corn rootworm may be more injurious increased by approximately % node of roots pruned than nonvariant populations to some YieldGard RW across the YieldGard RW hybrids. The range in injury hybrids. As indicated previously, the variant western across the commercialized hybrids was 0.62 (hybrid C, corn rootworm appears entrenched in east central Illi 83% consistent) to 0.91 (hybrid K, 55% consistent). nois. Further investigations are needed to confirm this These two YieldGard RW hybrids are the same two hypothesis. Eventually, it will be necessary to separate that displayed this range at the Monmouth site. As of variant from nonvariant western corn rootworms, then August 7, the two YieldGard RW hybrids that were not subject transgenic corn rootworm hybrids to precise commercialized, D and F, had root injury ratings of 1.50 infestation levels of both populations and evaluate root and 1.92, respectively. injury and adult emergence across the treatments. This past year, researchers took a step forward in being able to Did the overall root protection YieldGard RW hybrids separate variant and nonvariant western corn rootworm diminish at the Urbana location as compared with the populations. Monmouth site? An examination of the percentage consis tency (percentage of roots with a node injury rating < 1.0) In the August 2006 issue of Environmental Entomology, of the various hybrid treatments may help to answer this Lisa Knolhoff (graduate student in the Department of question. The percentage consistency of every YieldGard Entomology, University of Illinois at Urbana-Cham- RW hybrid (commercialized and noncommercialized) paign) and David Onstad, Joe Spencer, and Eli Levine was lower in the Urbana experiment as compared with (entomologists with the University of Illinois at Urbana-
90 ♦ 2007 Illinois Crop Protection Technology Conference Champaign and Illinois Natural History Survey) reported These researchers concluded in the abstract of their paper: how they could separate variant from nonvariant western “Results were consistent with the hypothesis that a loss corn rootworms using a behavioral bioassay. As the of fidelity to corn rather than any particular attractant authors indicated in their paper, this is the “first step is the cause of rotation resistance. Behavioral differences in determining the genetic basis of rotation resistance” between populations of beetles in similar environments (Knolhoff et al. 2006). suggest that there is a genetic difference between rota tion-resistant and wild-type D. v. virgifera, although no By measuring the time it took for western corn rootworm specific gene or genes have yet been identified.” adults to exit behavioral assay arenas, the investigators began to observe some interesting differences among In 2006, we conducted a very limited HxRW hybrid beetles that had been collected from different areas trial near Urbana (Table 6) to determine whether root (Monmouth, Perry, Urbana, Illinois; and Ames, Iowa). protection declined from mid-July to early August. Two The arenas were cylindrical and made of plastic mesh HxRW hybrids were provided by Dow AgroSciences screen with an opening in an inverted cone at the top. and two were provided by Pioneer Hi-Bred International, The authors made the following observation: “Results Incorporated. The identities of these transgenic corn from these assays indicate that D. v. virgifera females rootworm hybrids remain unknown to us. Although this from regions where crop rotation is no longer effective trial was much more limited in scope than the hybrid are more active than females from regions where rota experiments described previously for YieldGard RW tion remains effective,” Differences among variant and hybrids, it is a start in evaluating the effectiveness of nonvariant populations were more evident when the HxRW hybrids at early (July) and later root evaluation bioassay was performed in the field as compared with dates (August). The small set of HxRW hybrids that the laboratory. During 2004, beetles collected from we evaluated offered excellent root protection as of July Urbana were “consistently more active” than specimens 19 (Table 6). By August 7, the level of root protection obtained from Monmouth. Urbana is much nearer the remained excellent for the HxRW hybrids; only the Dow geographic epicenter (Piper City, Ford County) of where B hybrid (0.42 root rating) exhibited a moderate level it is believed the variant western corn rootworm had its of pruning. We hope to expand the number of HxRW origin. In 2005, western corn rootworm females collected hybrids we evaluate and use more than one test site in near Ames, Iowa, were theTeast active” as compared with the future. the beetles collected from Urbana and Perry locations.
TABLE 6. Root ratings1'2 and percentage consistency1 for HxRW corn rootworm hybrids, University of Illinois, UTbana3, 2006.
Hybrid Root Rating4 July 19 Percentage Consistency Root Rating August 7 Percentage Consistency Dow A 0.09 cd 100% 0.18 be 100% Dow B 0.17 c 100% 0.42 b 88% Dow C (UTC) 2.90 a 0% 2.94 a 0% Pioneer A 0.06 d 100% 0.18 be 100% Pioneer B 0.07 d 100% 0.14 c 100% Pioneer C (UTC) 2.58 b 4% 2.90 a 0%
1 Root ratings are based on the 0 to 3 root-rating scale developed by Oleson et al. (2005): 0.00 = no feeding damage; 1.0 = one node (circle of roots), or the equivalent of an entire node, pruned back to within approximately 3.8 cm (1.5 inches) of the stalk (or soil line if roots originate above ground nodes); 2.0 = two complete nodes pruned; 3.0 = three or more complete nodes pruned (highest rating that can be given). Percentage consistency is the percent age of roots with a node injury rating < 1.0. 2 Means followed by the same letter do not significantly differ within a column (P = 0.05, Duncans New Multiple Range Test). 3 All Herculex RW hybrids were planted on May 23, 2006, in a field that had been a trap crop (late-planted corn and pumpkins preceding year) near Urbana. ^Six randomly selected root systems were dug from the center two rows of each four-row plot (in each of four replicates) on July 19 and August 7, 2006.
2007 Illinois Crop Protection Technology Conference ♦ 91 Concluding Remarks References
In 2005, Bt hybrids were planted on 35% of the U.S. FernandeZ'Cornejo, J., and M, Caswell. 2006, The First Decade corn acreage (FernandeZ'Cornejo and Caswell 2006). of Genetically Engineered Crops in the United States . USDA The majority of these transgenic Bt corn hybrids were Economic Research Service, Economic Information Bulletin, aimed at the European corn borer. In 2003, Bt hybrids Number 11, Washington, DC. (M ON 863, Cry3Bbl, YieldGard RW) targeted at corn Gray, M.E., and K.L. Steffey. 1998. Corn rootworm (Coleoptera: rootworms were commercialized for the first time. In 2006, Chrysomelidae) larval injury and root compensation of 12 HxRW hybrids (DAS-59122-7, Cry34Abl/Cry35Abl) maize hybrids: An assessment of the economic injury index. were commercialized for the first time. These transgenic Journal of Economic Entomology 91:723-740. corn hybrids also are designed to provide root protection Gray, M.E., and K.L. Steffey. 2005. Transgenic YieldGard against corn rootworm larvae. In 2007, Syngenta intends rootworm hybrid stumbles in Urbana experiment: Why? to commercialize a new transgenic corn rootworm event pp. 41-46. In Proceedings of the 2005 Illinois Crop Protec (MIR604, mCry3A, Agrisure RW).The number of trans tion Technology Conference, University Illinois Extension, genic corn rootworm (Bt) hybrids available to producers Urbana-Champaign. continues to expand. The number of transgenic corn acres, especially those acres devoted to stacked hybrids Gray, M.E., K.L. Steffey, R. Estes, J.B. Schroeder, and D.M, (combinations of Bt events and herbicide tolerance traits) Bakken. 2006, Transgenic corn rootworm hybrids, soil is expected to increase quite significantly over the next insecticides, and seed treatments: Does anything work on the several years. It is imperative that research on the efficacy variant western corn rootworm? pp. 54-61. In Proceedings of these transgenic corn rootworm hybrids be continued of the 2006 Illinois Crop Protection Technology Conference, by land grant scientists in multiple locations across the University of Illinois Extension, Urbana-Champaign. Corn Belt. As we have demonstrated, in this technology’s Knolhoff, L.M., D.W. Onstad, J.L. Spencer, and E, Levine. 2006. infancy, not all transgenic corn rootworm hybrids (even Behavioral differences between rotation-resistant and wild- those with the same event) offer the same level of root type Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). protection against corn rootworms. Producers should Environmental Entomology 35(4):1049-1057. be equipped with as much information as possible in Oleson, J.D., Y.K. Park,T.M, Nowatzki, andJ.J.Tollefson, 2005. order to make the most informed pest management Node-injury scale to evaluate root injury by corn rootworms decisions. As the number of Bt acres increases, so, too, (Coleoptera: Chrysomelidae), Journal of Economic EntomoU will the selection pressure for resistance development by o g y 98:1-8, multiple insect pests of corn. This fact underscores the Siegfried, B.D., T.T. Vaughn, and T. Spencer, 2005. Baseline importance of strict adherence to resistance management susceptibility of western corn rootworm (Coleoptera: Chryso protocols that have been developed for these impressive melidae) to Cry3Bbl Bacillus thuringiensis toxin. Journal of pest management tools. Economic Entomology 98:1320-1324.
9* ♦ 2007 Illinois Crop Protection Technology Conference Seed-Applied Insecticides, Soil Insecticides, and Bt Corn: Their Roles in Corn Production ... ■ E | k Kevin L. Stejfey, Michael E, Gray, ' • ■ , ___-<■ ~~ Jared B. Schroeder, and Ronald E. Estes
y the simple act of planting com seed, a com grower Controlling aboveground insects (e.g,, European corn now has expectations for controlling a large list borer) is not efficient for only 20% of the corn. of potential insect threats, both below and above B All of the justifications for not planting non-Bt corn ground, depending on the product selected—black refuges seem to represent valid concerns, but the first cutworms, corn rootworms, European corn borers, bottom line is that the act of not planting a non-Bt corn southwestern corn borers, western bean cutworms, white refuge is an act of reneging on “binding contractual grubs, and wireworms, Throw in the promise of protection obligations on the grower to comply with the refuge against fall armyworms, flea beetles, grape colaspis, and requirements" (the grower agreement or stewardship seedcorn maggots, and a corn producer has what he or agreement). This act is punishable by the registrant of she has always hoped for— a simple, convenient, effective the product associated with persistent noncompliance way to control the most economically important insect (e.g., denial of sales of Bt corn products). In addition, pests of corn. No handling of insecticides, less scouting, "seed dealers who are not fulfilling their obligations to increased utilization of water and nutrients, increased inform/educate growers of their IRM obligations will yields, efficient weed control. W hat more can we ask lose their opportunity to sell [the transgenic Bt modified for? The so-called triple stacks (Bt for corn rootworms, corn].” Finally, each registrant of Bt corn products must Bt for borers, the herbicide-resistant or -tolerant trait), design and implement a comprehensive, ongoing IRM with all seeds treated with a neonicotinoid insecticide education program; design and implement an ongoing (either Cruiser or Poncho), fulfill many pest manage IRM compliance program; and establish and publicize ment wishes. a phased compliance approach. These requirements are If only we didn’t have to concern ourselves with those included in all corn biopesticide registration action docu annoying insect resistance management (IRM) require ments published by the United States Environmental ments. And with triple stacks, IRM requirements are Protection Agency (EPA). confusing. The second and more long-term bottom line is that Over the past several months, we have heard from numer widespread disregard for IRM requirements for Bt corn ous sources that some corn producers fully intend to will place significant selection pressure on a number of disregard the insect resistance management recommenda insect populations, including the ever-resilient western tions by not planting a Bt corn refuge. The reasons why? corn rootworm. The unfortunate end result of such selec It’s inconvenient to handle soil insecticides for only 20% tion pressure is that one or more pest insect populations of the corn acres. The yields in non-Bt corn refuges are will develop resistance to one or more active ingredients, noticeably lower than the yields of transgenic Bt corn fields. creating the potential for widespread failures of insect Not-Bt corn refuge acres have to be scouted regularly. control products and significant, possibly unprecedented,
2007 Illinois Crop Protection Technology Conference ♦ 93 yield losses. The potential economic ramifications of the throughout most of Illinois and the rest of the Midwest, development of insect populations resistant to insect However, our annual survey for second-generation control tactics (e.g., insecticides, crop rotation) are con European corn borers in 2006 revealed a resurgence of siderable. All of us involved in agriculture should know; European corn borers in some areas of the state, especially we’ve been down that road before. the central one-third (Table 1). The impact of Bt corn planted for control of corn borers was evident in some of The Future of Corn Insect Management Is the counties surveyed. For example, two of the authors All About Transgenic Hybrids—At Least surveyed ten fields in Morgan County in mid-Septem for Now ber; fields with significant infestations of European corn borers were unmistakable from the road— broken tops, All indications are that corn acres planted to transgenic lodged stalks. In five of the ten fields surveyed, 90% or hybrids will continue to increase. As seed companies more of the stalks examined were infested with European escalate the rate of incorporation of Bt traits and herbi corn borers (Figure 1). However, three of the ten fields cide resistance traits into their elite hybrids and as the surveyed had 0% infestation of European corn borers, and yield benefits of these converted corn hybrids become one of the fields had only 4% infestation. We assumed more widely publicized, the growth in acreage of single-, that these four fields had been planted to Bt corn for double-, and triple-trait hybrids will be extraordinary. control of corn borers. Although European corn borers Fernando-Cornejo and Caswell (2006) offered the were few and far between in the Southwest and South following statistics, among many others, regarding the east Crop Reporting Districts, there were indications of recent growth of the Bt corn market:'Bt corn, originally infestations by southwestern corn borers in many of the developed to control the European corn borer, was planted southern counties surveyed. on 35% of corn acreage in 2005, up from 24% in 2002. The recent increase in acreage share may be largely due So, isn’t Bt corn a good thing for corn producers, the to the commercial introduction in 2003/04 of a new Bt environment, and society in general? For the most part, corn variety that is resistant to the corn rootworm, a pest yes. Effective control of major insect pests of corn is a that may be even more destructive to corn yield than the significant economic benefit for corn growers who produce European corn borer.” There is every reason to believe continually higher yields, Bt corn is considered to be less that, barring the development of a major problem with environmentally disruptive than chemical insecticides, Bt corn, acreage of Bt corn will continue to increase at and effective host plant resistance is an integral part of a dramatic pace. an insect management program. In addition, the neonic- otinoid insecticides applied to Bt corn seed also seem to The concerns driving the interest in planting Bt corn have little impact on the environment. However, although are noteworthy. The range of the variant western corn some corn producers are tempted to plant Bt corn on rootworm that lays eggs in soybeans, as well as in other all of their acres, the potential ecological impact of so crops, continues to spread. Many corn producers have experienced or observed the impact of a heavy infestation of corn rootworm larvae in corn planted after soybeans. It’s also important to note that the western com rootworm still lays eggs in cornfields, so the projected increase in corn-after-corn acres also will be a market for Bt corn products. The continuing establishment of western bean cutworms also has many corn producers on the alert and speculating when Bt corn will help them avert significant yield losses caused by this ear-infesting pest. An overview of the spreading distribution of the western bean cutworm is provided in another paper in these pro ceedings—Western Bean Cutworm and the Invasion of Illinois Corn: It's Like Deja vu All Over Again. FIGURE i • Percentage infestation of European corn And consider “old foes.” For many years, populations borer larvae in ten randomly selected fields in Morgan of European corn borers seem to have been suppressed County, Illinois, 2006.
94 ♦ 2007 Illinois Crop Protection Technology Conference TABLE i • Results from the 2006 survey for second-generation European com borers, Illinois.
Counties1 and Percentage of European corn Counties1 and Percentage of European corn Crop Reporting plants infested, borer larvae Crop Reporting plants infested, borer larvae Districts 2001 per 100 plants Districts 2001 per 100 plants Bureau 26 25.6 Calhoun 40 67.4 Jo Daviess 12 25.2 Christian2 35 28.8 Mercer 9 23.0 Greene 63 104.0 Ogle 1 0.0 Madison 44 99.2 Whiteside 4 3.6 Montgomery 50 105.0 Winnebago 10 12.8 Morgan 57 124.0 Pike 44 39.6 Northwest 10 15.03 Sangamon 38 47.0 DeKalb <1 0.4 West Southwest 46 76.88 Kendall 6 8.8 LaSalle 28 29.6 Clark 57 77.2 McHenry 17 19.8 Coles 25 22.2 Will 14 5.4 Crawford 31 40.2 Effingham 30 40.2 Northeast 13 12.8 Marion 24 4.6 Adams 81 131.8 Shelby3 30 35.8 Fulton 43 80.4 Knox 24 23.4 East Southeast 33 36.70 McDonough 15 30.4 Jackson 0 0.0 Schuyler 35 63.2 Monroe 10 9.6 Warren 34 113.4 Pulaski-Alexander 0 0.0 West 39 73.77 Washington 20 21.8 Logan 25 48.8 Southwest 8 7.85 Macon 32 25.4 Franklin 2 0.0 McLean 21 34.2 Massac 0 0,0 Peoria 36 53.0 Saline 16 10.4 Woodford 42 59.8 Wayne 11 13.4 White 35 22.4 Central 31 44.24 Southeast 13 9.24 Champaign 22 8.0 Iroquois 10 10.2 STATE 33 23.24 Livingston 12 31.8 Vermilion 22 22.8 1 Unless otherwise indicated, 10 randomly selected fields were sampled in each county. East 17 18.2 217 randomly selected fields were sampled. 311 randomly selected fields were sampled.
much Bt protein in agroecosystems could turn short vided for each type of product. We have not listed the term economic gains into longer-term economic losses herbicide-resistant and herbicide-tolerant traits included and environmental disruptions, which ultimately will in the triple stacks. The focus in this paper is insect affect all corn producers. There are legitimate ecological management. reasons for the requirements of IRM strategies, and we Bt corn products for control of European and southwest strongly encourage their deployment. ern corn borers (as well as for different levels of protec tion against other caterpillars) have been commercially What Types of Bt Corn Will Be Available in available for several years, and corn producers in many 2007? areas have adopted their use. Bt corn products for control Table 2 shows the types Bt corn products that will be of rootworms were available for the first time in 2003 available in 2007, with a list of insects controlled pro (YieldGard brands). Herculex brands for rootworm
2007 Illinois Crop Protection Technology Conference ♦ 95 control were sold and planted commercially for the first letin. All of our efficacy data are published annually in time in 2006, Agrisure RW corn hybrids will be sold on Target, our summary of field crop insect management commercially for the first time in 2007. YieldGard VT trials (Department of Crop Sciences, University of Illinois (Vector-Stack Transformation, VecTran) is the name of at Urbana-Champaign, http://www.ipm.uiuc.edu/ontar- Monsanto's new, second-generation insect control tech get). Although all transgenic rootworm control products nology. The Bt proteins in the YieldGard V T hybrids are provide excellent control of corn rootworm larvae under the same proteins in other, equivalent YieldGard hybrids, most circumstances, there is evidence from both research but the method of transformation has been improved. trials and commercial fields of significant corn rootworm YieldGard V T corn hybrids will be available on a limited larval damage to these products. The reasons for these basis in 2007, instances of greater-than-expected corn rootworm larval damage are speculative. How effective are these products for controlling corn rootworms? Efficacy data for YieldGard Rootworm, All Bt corn products have been and will be sold with Herculex RW, and Herculex XTRA products are pub IRM refuge requirements. Planting non-Bt corn refuges lished in another paper in these proceedings—Transgenic is required for all types of Bt corn, whether the Bt corn is Corn Rootworm Hybrids: Assessing Performance in a intended for control of corn rootworms, European corn Variant Western Corn Rootworm Arena. Efficacy data borers, or both, and whether the brand is YieldGard, for transgenic Bt products also have been published in Herculex, or Agrisure. The basic rule is 20% non-Bt articles in the Bulletin, http://www.ipm.uiuc.edu/bul corn refuge and 80% Bt corn, again regardless of target
TABLE 2 • Transgenic Bt com products for 20071
Product Insecticidal protein Controls,..
Agrisure CB Cry lAb European corn borer, southwestern corn borer (also offers suppres sion of corn earworm, fall armyworm)
Agrisure RW mCry 3 A Western, northern, and Mexican corn rootworms Agrisure CB/RW Cry lAb + mCry 3 A European corn borer; southwestern corn borer; and western, north ern, and Mexican corn rootworms (also offers suppression of corn earworm, fall armyworm)
Herculex 1 Cry IF European corn borer, southwestern corn borer, western bean cutworm, fall armyworm, black cutworm (also offers suppression of corn earworm)
Herculex RW Cry34Abl/Cry35Abl Western, northern, and Mexican corn rootworms Herculex XTRA Cry IF + Cry34Abl/Cry 35Abl European corn borer; southwestern corn borer; western bean cutworm; fall armyworm; black cutworm; and western, northern, and Mexican corn rootworms (also offers suppression of corn earworm)
YieldGard Corn Borer Cry lAb European corn borer, southwestern corn borer (also offers suppres sion of corn earworm, fall armyworm, stalk borer)
YieldGard Rootworm Cry 3Bbl Western, northern, and Mexican corn rootworms
YieldGard Plus Cry lAb + Cry 3Bbl European corn borer; southwestern corn borer; and western, north ern, and Mexican corn rootworms (also offers suppression of corn earworm, fall armyworm, stalk borer)
YieldGard V T Rootworm Cry 3Bbl Western, northern, and Mexican corn rootworms
YieldGard V T Triple CrylAb + Cry 3Bbl European corn borer; southwestern corn borer; and western, north ern, and Mexican corn rootworms (also offers suppression of corn earworm, fall armyworm, stalk borer)
1The traits for herbicide resistance or tolerance are not listed in this table.
9 6 ♦ 2007 Illinois Crop Protection Technology Conference insect or brand of corn grown. For transgenic root- mental conditions may greatly affect the efficacy of soil worm-protected corn, the EPA requires that the refuge insecticides, and control failures with the modern products be placed within or adjacent to the field of Bt corn. For have occurred as a consequence. In addition, there are transgenic corn borer-protected corn, the EPA requires concerns about the persistence of soil insecticides applied that the refuge be planted within Vi mile of the field of in early April, Nonetheless, data published from many Bt corn. We strongly encourage corn growers to plant sources over the years substantiate that soil insecticides their refuges, regardless of the target insect, in the same are usually reliable products for rootworm control. fields where Bt corn is planted. Planting non-Bt refuges We will continue to recommend the use of both soil within fields of Bt corn will promote better mixing of insecticides and transgenic Bt corn hybrids for rootworm the insect populations from non-Bt corn refuges with control, when needed. Soil insecticides for rootworm insects that survive in Bt corn. control offer a couple of distinct benefits. Soil insecticides It is also important to note that one brand of Bt corn applied to non-Bt corn refuge acres protect against corn cannot be used as a refuge for another brand of Bt corn for rootworm larvae and satisfy IRM requirements. Addi the same target insect. In other words, Herculex RW corn tionally, the availability of multiple active ingredients for cannot be used as a refuge for YieldGard Rootworm corn, control of corn rootworms reduces the selection pressure or vice versa. However, transgenic corn borer-protected of any one active ingredient on rootworm populations corn can be used as a refuge for transgenic rootworm- and provides alternatives for rootworm management. protected corn, and vice versa, because the Bt proteins Significantly fewer alternatives will limit our responses expressed in the two different types of corn are targeted if widespread product failures occur. for different insects. For example, a YieldGard Corn Borer hybrid can be used as a refuge for a Herculex RW hybrid Concluding Remarks (but not for a Herculex XTRA hybrid). One of the best ways to reduce selection pressure on a There are other, more specific requirements for both corn pest population is to use a control product only when borer- and rootworm-protected corn that are not included necessary (e.g., pest insect density has exceeded an eco in this paper. We refer you to the original biopesticide nomic threshold). There are fully developed protocols registration action documents for many other specific and guidelines for sampling for western corn rootworm details about registered Bt events for insect control. adults in both corn and soybeans to determine whether a rootworm larval control product will be necessary the What About Soil Insecticides? following year. Many previous studies in midwestern states have shown that only about one-half of the corn acres In 2007, most farmers will continue to apply soil insecti harbor economic infestations of corn rootworms annually. cides for control of corn soil insects, and many producers The development of the variant western corn rootworm will apply soil insecticides to their non-Bt corn refuge that lays eggs in soybeans and the variant northern corn acres. However, as the acreage planted to Bt corn (includ rootworm that undergoes extended diapause are reasons ing triple-stack hybrids) increases, the acreage of corn to re-examine the annual levels of infestations of corn treated with soil insecticides will decline. This outlook for rootworms. However, it is certain that not all corn acres a shrinking market for soil insecticides has greatly slowed need to be treated with a soil insecticide or planted to a the development of new corn soil insecticides; there are Bt corn hybrid for rootworm control. Using a rootworm few chemical soil insecticides under development. control product only when it is needed is both economi Corn producers in the Midwest have relied on soil insec cally and ecologically sound. ticides for rootworm control for decades. Throughout the The other primary strategy for reducing the selection decades of their use, there have been some spectacular, pressure that Bt corn may place on corn rootworm popu widespread failures of some products to control rootworm lations is to comply with IRM requirements, a strategy larvae for various reasons (e.g., development of rootworm endorsed and explained thoroughly by the National populations resistant to insecticides, enhanced microbial Corn Growers Association (http://www.ncga.com) and degradation). Most of the soil insecticides currently all state corn growers associations. Stewardship of all of available for control of corn soil insects are reasonably our rootworm control products now should ensure their consistent in their efficacy against corn rootworms and use well into the future. some of the secondary insect pests. However, environ
2007 Illinois Crop Protection Technology Conference ♦ 97 References Some of the research described in this paper ILLINOIS was supported by funding from the Illinois Fernandez-Cornejo, J,, and M. Caswell. 2006. The First Decade SOYBEAN Soybean Association. of Genetically Engineered Crops in the United States , USDA ASSOCIATION Economic Research Service, Economic Information Bulletin, Number 11. Washington, DC,
9 8 ♦ 2007 Illinois Crop Protection Technology Conference Who’s Your Neighbor?
Jack Erisman /.;
He who reviles his neighbors has no sense, but the Organic ideology and the market influence of more spe intelligent man keeps silent cialty crops are permeating the countryside. This presents a diversity in which profit potential and livelihood and/or —P r o v e r b s 1 1 :1 2 lifestyle can be greatly challenged, regardless of which side of the issues one may be on.
ur culture has nearly transcended the time when Each of us needs to diligently seek the information neces neighbors are a large part of our support system, sary to keep us out of harm’s way. It will be much more be it physical or spiritual. Most of us consider palatable and psychologically reassuring if we really do neighborsO as those geographically close to us; however, understand each other’s individual pursuits. Hopefully, out rural and urban evolution and communications and travel of these efforts, some healthy mutual respect will prevail. technology have made many of us neighbors who didn’t Having that understanding and respect will allow us to necessarily choose such circumstances. objectively execute our undertakings without infringing on the welfare of each other.
2007 Illinois Crop Protection Technology Conference ♦ 9 9 Managing the Risks of Custom Application: An Industry Perspective Jean Payne
ustom application is an integral part of the com and the company itself. The fact that EPA filed charges mercial crop protection industry. Although this is not so shocking, but the fact that the charges were service normally is bundled with the purchase criminal was. Never in the history of enforcement has a ofC a crop protection product, with the erosion in profit pesticide application incident been pursued in a manner ability in the crop protection sector, custom application that could potentially result in a federal felony convic may be a service that will stand on its own in terms of a tion, This means the commercial applicator and operator profit center for agrichemical retailers. CropLife magazines could end up in federal prison and face lifelong branding recent survey of the top 100 agricultural retailers suggests as felons, just for doing their jobs. The implication for that the value of the crop protection market to agricul these two men and the company was frightening; the tural retailers dropped $800 million from sales figures impact of the case on the custom application industry reported in 2005. That’s troubling, but the good news is as a whole could fundamentally affect the future of the that custom application service overall has expanded for pesticide industry. most dealers as evidenced in increased equipment invest In the end, the vigorous defense presented by the agri ments and acres serviced. Something has to take up the cultural retailer prevailed, and a federal judge dismissed slack for the devaluation of crop protection products, the case. It was a victory for the agricultural retailer and and custom application has the potential to become a the industry, but the defense costs exceeded $200,000. more profitable enterprise. In this case, our industry was very fortunate that this But inherent in custom application is risk: from a civil, agricultural retailer had the resources to defend itself and environmental, and even criminal standpoint. The envi prevail. Had the retailer lost this case, can you envision ronmental activists, who are dogged in their efforts to your company trying to hire commercial applicators to reduce and even eliminate pesticide applications, have work for you, knowing that legal precedent had been applied numerous strategies to raise the risk level within set that could subject them to prison time for applying our industry. chemicals? Would anyone want to work in our industry at all when faced with this possibility? Had this case gone Illinois had the distinction in 2005 of being the first the other way, the environmental groups who are already state in which an agricultural retailer and member of the notorious for using the judicial system to influence public Illinois Fertilizer and Chemical Association (IFCA) was policy would have seized on every opportunity to brand subjected to criminal charges by the U.S. Environmental our industry as criminals for applying pesticides. We would Protection Agency for an alleged spray drift violation. In constantly be defending ourselves in a court of law. this case, constant letter-writing and emotional appeals over a 5-year period by a person who felt wronged by a And when it comes to“branding” our industry, the envi pesticide application resulted in Region 5 filing charges ronmental groups have recently been successful in coining against the commercial applicator, the licensed operator, a new phrase for pesticide application: “criminal trespass.”
lOO + 2007 Illinois Crop Protection Technology Conference This is another attempt to influence the emotions of the the policy. If farmers understood the stakes, would they public when it comes to pesticide application. As a nation, really want to take on the liability that custom applicators we have little sympathy for people who infringe on our deal with on a daily basis? Would that really be good for property without permission. Branding pesticide appli farmers? A majority of the producers decided it would cations as “criminal trespass" implies that our industry not be, and the idea was soundly defeated by the Farm has no regard for someone else’s property. Activists want Bureau’s voting delegates. Why? Because, over the years, the public to believe that “criminal trespass" of pesticides the IFCA and our members have been very involved will result in“multiple chemical sensitivity" syndrome for in educating not only farmers but also legislators and anyone living in an agricultural area. You will see the term the general public about the professionalism of custom “criminal trespass" more and more both in the courts and applicators and the increasing liability we face when we in the public policy debate, so be prepared to respond if apply agrichemicals. It paid off in this instance because you get criticized or questioned. we have been able to “brand" ourselves as consummate professionals when it comes to agrichemical applications. If The U.S. government has determined that proper and we remain committed to stewardship, to communication, necessary pesticide applications are legal, not criminal. and to promotion of practices that reduce the likelihood Producers have the right to protect their crops. And of drift, our image and our ability to protect the custom professional custom applicators are best equipped to application industry will remain strong. handle the application of agrichemicals, taking into account the risks and responsibilities inherent in each Is it a perfect world out there? No, not by any means. We application event. know that some people skirt the law regarding custom application versus private application. But we are no dif As a professional custom applicator, how do you best ferent than any industry because regulations serve mostly manage your risk when the stakes have gotten so high? to govern those who obey the laws. In a free society, there There is no form you can have your customers sign aren’t enough law enforcement officials to track down to absolve you of risk. But as a bonded, licensed, and everyone who disobeys the law. trained commercial applicator, your advantage over private applicators is that you do take on the risk and Therefore, voluntary compliance is crucial; doing the right liability of the application itself. I say “advantage” because thing is important. As maddening as it is when people flout it is an opportunity to present the value of this service the law, it usually catches up with them at some point. to your customers and to charge accordingly. Charging You may not read about it in the paper, but the scales do for services is not something our industry has been very balance. If not, the custom application business would successful at, but, over time, this can change. Commit cease to exist at all and certainly would not be growing. ting yourself to informing your customers about your We provide a valuable service to producers and to society. liability and the associated costs will eventually work its Although it seems thankless at times, I can tell you it is way into the psyche of the agricultural producer. Let me appreciated by many in the both the private and public provide an example. sectors. Custom applicators are often taken for granted; that's a sign that we are doing things right. In 2005, some producers made an attempt to seek approval of a policy that would direct the Illinois Farm Our industry does not have an easy answer to the issue Bureau to lobby for changes in the Illinois Pesticide Act of liability. Custom applicators will continue to be tar to enable private applicators to spray for hire but without geted by activists and by government agencies that are having to be licensed as a commercial applicator or have influenced by political agendas. As an applicator your best the required insurance. From a farmer’s perspective this defense— and offense—is to document your practices, would be great, right? W hat private applicator with their make sound decisions, and promote professionalism. own sprayer wouldn’t want the opportunity to get paid Define your image with your actions and with your for application services without being subject to the cost words. In Illinois, our industry has been successful in of the commercial license and insurance? maintaining a strong agrichemical application industry despite the fact that our legislature and state agencies The IFCA and our members engaged in this debate are increasingly becoming governed and influenced by with members of the Illinois Farm Bureau and worked a very urban population base. Our ability to survive in with producers to present reasoned arguments against this challenging environment is directly influenced by our
2007 Illinois Crop Protection Technology Conference ♦ 101 commitment to stewardship and the fact that we stand unless you allow it. Stand up for your principles and behind our principles. your professionalism, and you can limit your liability in the long run. In the end, whether in a court of law or in the court of public opinion, no one can tarnish your image overnight
102 + 2007 Illinois Crop Protection Technology Conference Surviving on the Fence Between Emerald City and Oz Donald Meyer ill# iftllll .
About the Title fighting again—with pesticide use as the latest chapter in the land rights issue. was invited to speak at this conference about the challenges caused by the urban sprawl that continues Since the time I agreed to present a perspective for this to encroach on agricultural areas of McLean County* conference, another issue has been added, which is also LikeI most Illinois counties, McLean has an increasing related to the use of pesticides— a situation that is becom number of new residents who have moved into the ing increasingly common in McLean County as a result of rural area, just far enough away to escape the rigors and the more conventional“pesticide-dependent”approaches chaos of urban neighborhoods* These former urbanites to farming in commodity agriculture and the increasing sometimes are not aware of the “challenges” that some acres being shifted toward an organic consumer* times go along with the “opportunities” of living in the Many of the following points are applicable to the dilemma country* It is a situation not uncommon in most of the of pesticide application challenges. United States, and there are even brochures written for the new rural dwellers, such as the “Code of the West” Speaker Perspectives or the “Code for Midwest Rural Living,” to share what rural residency can be like. I have served McLean Couny citizens for almost 24 years, since I left teaching and became first the agriculture Extension speakers (like me) may walk rather unusu Extension adviser and now the county director for the ally because of the many years spent straddling a fence Extension office in McLean County* My background is between “Emerald City,” as in the urban dream, and the in farming; I grew up in McLean County and obtained more typical rural life, out in the farmland of “Oz*” Some agricultural education degrees (bachelor’s and master’s). days that fence is a pleasant board fence on which to be In my role with the Extension office, I serve county seated, with the research-based and environmentally farms and agribusinesses and also assist urban clients appropriate aspects of farming in the county on one with horticulture programming* McLean County is a side and the rights of a nonfarm resident, either on the rapidly growing county in terms of population, with a edge of sprawl or on an 5-acre island plot in the middle hub metropolitan area of Bloomington/Normal. of a large farming county, on the other. Other days that same fence can be a bit “chafing,” as if it were made of McLean County Agriculture Background barbed wire, because there are unfortunate accidents caused by pesticide application mixed with nature (drift) Nearly every year, McLean County continues to be the that cause rifts between neighbors. Finally, on a few days nation’s top-producing county for com and soybeans, each year, the fence feels more “electric,” when a current recently producing more than 58 million bushels of corn alleged incident fuels a long-standing dispute between and more than 14 million bushels of soybeans* In 2003, neighbors— almost as if it were the Hatfields and McCoys McLean County had more harvested corn acres than 26 entire states did, and we produced more corn than 30
2007 Illinois Crop Protection Technology Conference ♦ 103 entire states! McLean County also outproduced 28 states of common perceptions of agriculture. In addition, farm in soybeans in 2003* Hie 2002 U.S, Census of AgricuL operators must be conscious of their rights and responsi ture lists 1,442 McLean County producers farming more bilities regarding the use of pesticides and at the same time than 688,000 acres of farmland. Annually, more than 200 must remain conscious of the rights and responsibilities million bushels of agricultural commodities are produced of their nonfarm or organic-farming neighbors. here, with farm income derived at 87% from crops and To begin to solve the problem, solutions may be best 13% from livestock. In terms of total market value of offered as a review of generally accepted rights and production, McLean County ranked 138th out of 3,078 responsibilities. counties in the 2002 U.S. Census of Agriculture. Conventional farmers in “Oz" generally have the follow McLean County Urban Background ing rights on the agriculturally zoned land they own or manage, iheycan Even with all of that agricultural production, McLean County’s urban growth has been on the rise. The U.S. ♦ grow whatever “lawful" crop they wish Census reported a county population growth of 16.5% ♦ work in the fields any day or under any conditions from 1990 to 2000, almost double the rate for Illinois. The county has the 13th highest population in the state, ♦ graze whatever livestock they wish with 150,453 residents in 2000, and has gained 21,253 + protect their growing crops in any lawful way neces residents since the previous census. The projected popu sary lation for 2004 is 158,006 residents. Our growth rate from 1990 to 2000 was the 10th fastest county growth ♦ harvest the crop whatever day they select rate in Illinois. ♦ drain their water onto others' property, as long as it doesn't interfere with natural drainage patterns Now—The Situation W ith those rights come responsibilities pertaining to that You may know the situation well! We depend on pesticides same land. Farmers have the responsibility to to provide inexpensive input costs and minimum tillage approaches for most farms in Illinois. Pesticides save ♦ keep plants growing inside property lines time, enable farming of more acres, reduce erosion, and ♦ keep livestock within property lines minimize fuel costs. Years ago, product uses were based ♦ keep crop protection products within property lines on a fieldwide, large-volume, broad-spectrum,“if it crawls, flies, or walks, it will kill them" type of chemistry. Today, ♦ accept water that naturally flows toward their prop products are more specific-pest targeted, applications erty can be site-specifically satellite controlled, and available The home owner or organic farmer living on the edge products are more ecologically appropriate. of “Emerald City" or out in the country of “Oz" also has However, even with these advances in product chemistry certain rights and responsibilities. Nonfarm residents and site application, many nonfarm residents do not and organic farmers adjacent to traditional farms have appreciate what agriculture is doing and how it is doing it. the right to Countless news features every year intensify the opinions ♦ grow whatever legal plants they wish to grow on their of nonfarm citizens, and those in agriculture have become property further removed from the 98% nonfarm citizens. ♦ enjoy air and water that is not affected by adjacent As the U.S. population continues to shift from the agrarian activities society of yesteryear and as the number of farmers as a percentage of the whole population continues to reduce, + not be threatened by drift from crop-protection prod our message is conveyed with even more difficulty to a ucts nonfarm public. In agriculture, farmers are using research Similarly, nonfarm residents and organic farmers have to back up their methods, are concerned about protecting the responsibility to the growing crops and environment, and are furnishing what is still believed to be one of the safest and cheapest ♦ keep their plants growing and personal property within food supplies in the world. Yet they do need to be aware property lines
104 ♦ 2007 Illinois Crop Protection Technology Conference ♦ keep their children and animals away from growing damaged by pesticides will likely outweigh any benefits crops and livestock to that approach. Once a pesticide is alleged to have drifted off-target, the “victim” generally opens a watch ♦ not trespass onto farm property for hunting, ATV ful eye to all of the outdoor plants. All of a sudden, riding, or other leisure activities concerns about myriad types of “nonchemical” plant W hen one person’s rights are infringed on by another’s damage— even from routine, naturally occurring plant activities, conflicts can occasionally arise. Remember the diseases related to weather that ordinarily might have standard rule, “Your rights end where my rights begin!’’ gone unnoticed—somehow become associated with the pesticide application. Real-Life Situations As always, the past seems simpler. Years ago, if livestock Let’s review some real-life situations that have occurred: was grazed on farm property, the fence law required Situation 1: Farmer Smith sold off a farmhouse and 5 property owners on both sides of the property line to acres no longer needed by the farming family. Nonfarm maintain a working fence to protect the rights of both resident Jones purchased the property surrounded on owners. Because we cannot easily “fence” pesticides, what three sides by farmland. Smith now farms up to the precautions might be considered to prevent problems? property line and sprays within a 30-inch row width of ♦ Apply only according to pesticide label instructions and the Jones property. when weather conditions are appropriate, as specified Situation 2: Farmer Smith has farmed his property for on the label? more than 30 years. A neighbor just sold the adjacent ♦ Apply products least likely to drift, if such choices are property for development, and now a line of houses have available, or with approved additives to minimize the been built along the unfenced border. Most of the adja drift? cent property owners are more than one generation from ♦ Discuss during the off-season which farm products farming and do not like the dust, noise, and occasional will be used? pesticide use on the farm. Situation 3: Farmer Smith has farmed his property for ♦ Agree on a “demilitarized” zone from each side of the line? (For example, no “at-risk” vegetables or ornamen more than 30 years. Farmer Jones just switched from conventional commodity farming to organic vegetable tals to be grown, or no farming to within so many inches of the property line)? production. ♦ Establish a good relationship by sharing “rights” in Situation 4: Farmer Smith finally “caved in’’ to sprawl exchange for the “risks” (post-harvest gleaning of fields, and development and sold 40 acres to a developer. The developer experienced a slowdown and could not get hunting rights, ATV or horse riding, tractor rides, houses built promptly. Developer Jones hired lawn care snow plowing furnished, sharing of garden produce company Meyer (or agribusiness firm Meyer) to treat the grown, hiring of family members to assist with the property with herbicides because weeds have overgrown farm, etc.)? the former farmland, and the city ordinance requires ♦ Alert the nonfarm resident or organic producer when mowing or weed control. spraying is scheduled?
What Can We Do? ♦ Provide educational materials about pesticides, farming methods, and integrated pest management Regardless of the situation (whether similar to one practices? described above or another, unique situation), there is ♦ Work with authorities to provide zoning protections always more than one approach to trying to meet this (including “agricultural zones”) to limit sprawl? growing challenge. ♦ Flire an agribusiness company or cooperative to do Farmers and applicators need to avoid the “Rambo” the pesticide application to pass along the liability? approach, aggressively trying to muscle their way into the future, and lose the attitude of “we were here first.” ♦ Use pesticides only as needed, as part of an integrated The liabilities and costs to replace consumer products pest management program?
2007 Illinois Crop Protection Technology Conference ♦ 105 ♦ Work with Realtors and obtain their assistance in and the agricultural community with agricultural aware explaining agricultural zoning and life in that zone? ness activities. We can also provide education on these issues to decision-making authorities. + Other ideas? Extension involvement pertains largely to education about What Is the Role of Extension? pesticide use or alternatives to their use. Occasionally, we University of Illinois Extension provides workshops and process samples of agricultural or horticultural plants that may be showing a pesticide drift symptom or another materials (publications, CDs, workbooks) to assist in training farmers and commercial pesticide applicators problem that may have surfaced due to a concern about about pesticide safety. Extension's role is education of potential drift. Enforcement, however, belongs to the pesticide applicators, property owners, and residents, Illinois Department of Agriculture, with follow-up from an area IDA field representative after a written complaint and we can also assist with providing researched-based recommendations to determine whether pesticide appli has been filed with the department. cation is appropriate. In conclusion, we need to continue to work together to increase consumer awareness of agriculture, ensure Educational resources about spray drift are available on research-based information to support an integrated pest the Web at http://www.pesticidesafety.uiuc.edu/facts/ management program, and educate all pesticide applica drift.html. tors about following label directions and safe handling In addition, we can assist other local groups in sharing and application of pesticides. information and building trust between nonfarm citizens
106 2007 Illinois Crop Protection Technology Conference A Regulatory Perspective on the Rural Agricultural Production/Urban Interface Gerald Kirhach
n recent years, the Illinois Department of Agriculture crops have to be planted, (3) they were there first, and has investigated several complaints filed by "nonag (4) delays could affect their standard of living if crop ricultural" residents related to alleged pesticide drift yields are reduced. The neighbor seems insensitive to the ontoI nontarget areas. Many home owners are attracted to compelling need of the producer to plant the crop and to life in the*country” and assume it is a pristine environment the diminishing window to maximize yields, and doesn't with beautiful crops growing fresh produce from their understand that there is little or no potential threat to garden and orchards. Producers assume that their "new" his or her health or property. neighbors understand modern crop production and the Failure of a producer to respond to a neighbor's inquiry or use of pesticides. Usually, neither assumption is true. complaint in a diplomatic manner almost always results Many rural home owners with an urban background plant in a complaint being filed with the Illinois Department of garden plots to supply their needs during the growing Agriculture. Lack of understanding of agricultural produc season; these plots range from small to extremely large. tion does not provide a basis for a producer to respond Whenever problems arise in their produce area, their improperly to the inquiry or complaint. Statements such first thought is that a pesticide application made by as "It is none of your business” or "I don’t care if you like a neighboring producer is the cause. Consequently, a it or not” will only ensure escalation of the complaining complaint is filed. Many times, a complaint is based on individual’s desire to seek further assistance. an odor that was experienced during the application. The Many times, a heated exchange occurs between the two assumption is that if the pesticide can be smelled, there parties and builds into a confrontational relationship. is contamination on their property and the produce is no Producers have been accused of refusing to provide longer viable for consumption. This determination occurs information about the active ingredients applied to the even when there is no damage observed to the growing neighboring fields. The rural resident will plant garden plant material. Some rural residents do not even realize plots next to the property line to maximize the potential that the producer used the same active ingredient (e.g., of drift on his or her property. Finally, throughout the glyphosate) that they used in their own lawn, garden, entire process, the department is saddled with the burden or orchard. some task of investigation, collecting evidence (including Many times, producers feel pressure to get the crop planted interviews), and making a final determination regarding and apply pesticides by a certain date, particularly when pesticide misuse. Often, the parties interviewed are hostile, there have been weather-related delays. As a result, poor and claims on both sides can be exaggerated. Many times, decisions may be made, possibly resulting in the presence neither party ends up happy or satisfied with the outcome. of a pesticide in a nontarget area (drift). Frustrations may The rural resident simply wants restitution and assurance arise in producers because (1) of the late planting period, that the incident will not be repeated. The applicator is (2) the "neighbor” doesn't seem to understand that the frustrated with the minimum level of enforcement, which
2007 Illinois Crop Protection Technology Conference ♦ 107 is an advisory letter indicating that there was a minimal centers on the long-term impact. Will an alleged exposure level of misuse but not enough for the department to to pesticides remove organic certification in future years pursue a more significant enforcement action* and, if so, for how long? The department’s investigation process includes all The department does not have any means to evaluate resources available to make a final determination consistent these situations, particularly if no background samples with the mandate specified within the Illinois Pesticide were collected and analyzed prior to the implementation Act, such as interviews, collecting samples for analysis of organic production. Today’s analytical equipment has with sensitive analytical equipment, taking photographs, the capability to detect trace amounts of active ingredients and ensuring that the application was made in compliance in parts per trillion. Should the determination be based with state and federal laws* The Illinois Pesticide Act on metabolites of the active ingredient as it breaks down? contains a clearly defined matrix with a point system for W hat is the impact on soil microbial activity to break determination of penalties. It contains various sections down the active ingredient in a timely manner? Does the that are scored by a group of three staff members. The level of detected active ingredients have a direct impact results are summarized and a finding is issued, based on on tolerances of crops planted the following year? All of internal review. these questions, while pertinent, are not easily answered with the available data. A few years ago, a dealer failed to adequately respond to a neighbor s complaint concerning drift of a pesticide to Summary their property and animals. The applicator ignored the concern, felt the situation could not be resolved, and Currently, the department makes a determination that applied pesticides in a similar manner the following year. a pesticide was misused based on the evidence collected The department investigated the complaint and found after the complaint is filed. To date, there has been no that drift had occurred during both applications. The determination of damage based on subsequent loss of presence of a pesticide was found through analysis of soil income, due to a lack of statutory authority in this arena. and plant samples. The situation escalated to a point that Any producer who wishes to be compensated for damage criminal charges were filed by the United States Attorney during the current growing season or subsequent years General’s Office, and an investigation was conducted by will be forced to seek restitution through the civil court the Criminal Investigation Division of the United States system. Environmental Protection Agency. The case was eventu A more immediate solution to the problem can be ally brought before the courts and resolved, but attorney achieved only through mutual cooperation, diplomacy, fees were large for both parties. and outreach from all groups involved. Conventional pro ducers have had success in producing a commodity near Organic Production organic production through advance work and outreach. Producers today are looking for marketing niches or Identification of sensitive areas, strong communication specialty markets that can provide a higher return to between both parties during the planting season, and a their operations. These options may include establish commitment to work together toward a common goal ment of vineyards or vegetable production, A growing of economic viability through their respective choice of segment is organic production of fruits and vegetables. production, either conventional or organic, have brought The marketplace has become more health conscious success in some areas. and is willing to pay a premium for commodities grown Failure to work together will almost always result in without the application of pesticides. adversity, confrontation, and frustration with each other. This trend has created some opportunities for agricultural If the department is included in the complaint process, production and some obstacles for production by con a determination of whether pesticide misuse occurred ventional means. A concern that seems to arise during will indeed be made, but it will not necessarily resolve any complaint investigation involving organic production the situation to everyone’s satisfaction.
108 ♦ 2007 Illinois Crop Protection Technology Conference Identifying and Protecting Organic Farms from Contamination .... with Prohibited Substances Cissy Bowman
What Is an “ Organic” Farm? stance to any field, production unit, site, facility, livestock, or product that is part of an operation;...” arms that sell food labeled“organic” must be certified by a USDA accredited certifying agent according Scope of Certification Fto the rules of the National Organic Program (NOP). The NOP was established under the Organic There are currently four types of organic certification Foods Production Act (OFPA), which was passed as part under NOP: production (farm), livestock, wild crop of the 1990 Farm Bill. The intent of the regulation was production, and handling facilities. A pesticide applica to create a consistent meaning for the word “organic.” tor may find himself or herself working on or near any one of these operations. Prohibited substances have the The NO P was implemented on October 21, 2001. The potential to contaminate not only soils or plants but rule is set forth in the Code of Federal Regulations (CFR), also animals and the food-contact surfaces of process Part 205. Full and updated copies of the act and the rule ing machinery, storage facilities, harvest equipment, and are available on the N O P Web site at http://www.am s. transportation vehicles. The potential for contamination usda.gov/nop. The NOP rule is the same for all certi exists anywhere organic food grows or with anything it fiers in all states. touches throughout its planting, growth, harvest—all Drift is the main concern for pesticide applicators and is the way to its sale to the consumer. defined in the rule as “the physical movement of prohibited substances from the intended target site onto an organic What Is Prohibited? operation or portion thereof.” According to CFR §205.105, a product that will be sold Organic farms, in order to be certified, must submit an or labeled as “100 percent organic,” "organic,” or “made Organic System Plan (OSP) to the certifier for approval. with organic (specified ingredients or food group(s)),” This plan addresses all inputs used on the farm as well as the product must be produced and handled without the how the operator intends to prevent drift or contamina use of synthetic substances and ingredients unless they tion with prohibited materials. To become certified, the appear on Environmental Protection Agency’s national land must have been free of the use or application of list of allowed substances. There are also some natural or prohibited substances for at least 3 years. “Application” “nonsynthetic” substances that are prohibited in §205.602 need not be intentional use by the farmer. Drift can be or §205.604. unintentional application. A synthetic, under the rule is “a substance that is for Under CFR §205.400, a person seeking to receive or mulated or manufactured by a chemical process or by maintain organic certification under the regulations must a process that chemically changes a substance extracted “(f) Immediately notify the certifying agent concerning from naturally occurringplant, animal, or mineral sources, any: (1) Application, including drift, of a prohibited sub
2007 Illinois Crop Protection Technology Conference + 109 except that such term shall not apply to substances created, Agriculture Statistics Service (NASS) also maintains a by naturally occurring biological processes*” database of organic operations. In general, this means that most synthetic pesticides and As part of an OSP, a certifier expects the operation to fertilizers, and those that contain synthetic inert ingredi document its procedure for avoiding drift. This procedure ents that are not on EPA List 4 (generally recognized as may involve any of a number of approaches, as appropriate safe, GRAS), are prohibited. Prohibited materials include to the individual operation. Some operations post signs. synthetic seed treatments. Use of or contamination with Others send letters to notify potential applicators that prohibited substances results in certification being denied their farms are organic. This procedure is fairly easy to for 3 years. There are exceptions under the Emergency do when dealing with county or state road maintenance Treatment Program. Under CFR §205.672/when a pro crews, but it tends to get more difficult when neighbor hibited substance is applied to a certified operation due ing farms use hired applicators. Communication is key to a Federal or State emergency pest or disease treatment to avoiding problems. program and the certified operation otherwise meets the The most common preventive measure is the creation of requirements ... the certification status of the operation a“buffer zone” on the organic farm. A buffer zone, under shall not be affected as a result of the application of the the regulations, is “an area located between a certified pro prohibited substance: Provided, that: (a) any harvested duction operation or portion of a production operation crop or plant part to be harvested that has contact with and an adjacent land area that is not maintained under a prohibited substance applied as the result of a Federal organic management, A buffer zone must be sufficient or State emergency pest or disease treatment program in size or other features (e.g,, windbreaks or a diversion cannot be sold, labeled, or represented as organically ditch) to prevent the possibility of unintended contact produced...” by prohibited substances applied to adjacent land areas with an area that is part of a certified operation.” Where Are the Organic Operations? Historically, a 25-foot buffer was considered to be Organic certification has grown very rapidly and encom appropriate. Over the years, however, we have realized passes the entire United States and much of the rest of that there is no magic number. The certifier and the the world. Increasing demand will result in continued farmer must identify what is right for the operation. A growth. Some companies are literally out looking for new trained, on-site inspector will analyze and report on the organic farmers. To the best of my knowledge, Illinois effectiveness of the proposed buffer zone. The inspector currently has about 200 certified operations, consisting may recommend that the buffer be increased or improved. of all types of certification. In cases for which there is suspicion of drift or potential The best way to avoid accidental application (drift contamination, the inspector may recommend or perform or otherwise) of prohibited substances on an organic a residue test. operation is to know where they are. This can be best In a handling operation, potential for contamination is done by a little research before taking any chances. The most likely to occur inside the facility. As part of its OSP, NOP Web site has a list of certifiers and their contact a handler must identify what methods are used for pest information at http://www.ams.usda.gov/nop/Certi- control. If prohibited materials are used, there must be fyingAgents/Accredited.html. Some certify across the a process for, and records kept of, how organic products country. Others certify only in a state or a region. The were protected. In general, we prefer to see such facilities primary certifiers operating in Illinois at this time are use approved materials. Indiana Certified Organic (ICO) and the Organic Crop Improvement Association (OCIA). On farms and handling operations, if contamination is suspected, residue tests will be conducted. Such tests are In the 2002 Farm Bill, appropriations were made to costly, and contamination must be reported. According offset the cost of certification. These funds were used to CFR§205.671, throughout 2006 and administered by state departments of agriculture. The Illinois Department of Agriculture When residue testing detects prohibited substances at should be able to provide a list of operations that received levels that are greater than 5 percent of the EPAs tolerance cost share. This list may include other certifiers' names for the specific residue detected or unavoidable residual and may help you in identifying them. The National environmental contamination, the agricultural product
IIO ♦ 2007 Illinois Crop Protection Technology Conference must not be sold, labeled, or represented as organically produced. The Administrator, the applicable State organic program’s governing State official, or the certifying agent may conduct an investigation of the certified operation to determine the cause of the prohibited substance.
It’s Not Just About Certified Organic Farms There are people today who have gardens and lawns that they maintain organically. There are also organic farmers who are exempt from certification because they fit into the “small farm exemption.’’ These are people who gross no more than $5,000 per year for the sale of organic products. These people are more difficult to identify than certified farmers; however, they often display signs notifying that they do not use pesticides. Such signs often display ladybugs or other beneficial insects, but terflies, and/or statements such as “Pesticide Free Zone” or “Organic Garden. Do Not Spray” (Figure 1). These materials and is not based on years of “abstinence” from signs are displayed for a reason and should be taken using prohibited materials. The only way to fail to meet seriously. Damage can be done to noncertified land as the standards is to refuse to meet requirements. Thorough well. Gardeners and home owners who choose not to use clean-ups and adoption of approved or allowed alterna synthetic pesticides do so for many reasons and should tives are the answers to “mistakes.” be respected, as well. When Accidents Happen... What Happens If Drift Occurs? Applicators do not go out of their way to apply materials Drift of prohibited substances takes land out of organic unless they have been hired to do so, but accidents do production for 3 years. The next crop to be called organic happen. ICO has seen some cases that have helped us cannot be harvested until at least 3 years after the date of create a process for reacting to witnessed or suspected the application or drift. This causes harm to the farmer drift. For example, because he or she will lose the organic premium. Prices for organic crops are higher than those for conventional ♦ A herbicide is being applied to a farm that neighbors crops. The damage to the farmer’s marketing abilities will an organic farm. The organic farmer is outside and vary based on what is being produced and how much notices that the spray is going onto his crops. Although crop was contaminated. he has a buffer, he knows there is contamination with a prohibited herbicide to his nonbuffer, organic crops. It is important to keep in mind that drift can damage a farmer who is “transitioning” to organics, as well as a This farmer took immediate action. He contacted his certified farmer. If it occurs in the transition period, it sets neighbor to find out who was doing the application the farmer back 3 years. Identifying transitional farmers and what was being sprayed. He obtained information is difficult because they are not required to be certified about wind speed and direction that day. He contacted or inspected, but that does not mean they should not the company that hired the applicator and told them document their practices. Indeed, they are required to he had witnessed drift. He took pictures of the sub keep records and submit them to the certifier upon initial sequent damage. He notified his certifier and asked application. Transitional farmers need to monitor drift how his plan needed to be changed based on the drift. as much as the certified farmer does. More than one-third of his field showed signs of drift. He worked out the necessary changes on certification Handling operations can usually find a way to clean up for that part of his field with his certifier. Payment for contamination or change their system plan to stop the damages was arranged between him and the company problem. Their certification is based on their willingness who hired the applicator. The amount has not been to come into compliance with appropriate methods and/or disclosed but was likely based on the difference in
2007 Illinois Crop Protection Technology Conference ♦ 111 organic price compared to conventional price for the the State organic program’s governing State official crops he will raise there for the next 3 years* In this by the applicable certifying party that requested case, there was no doubt about contamination because testing; and it was witnessed and there was obvious damage to the (2) Will be available for public access, unless the testing crop. is part of an ongoing compliance investigation. ♦ An insecticide has drifted onto an organic farm. (e) If test results indicate a specific agricultural product Although no one saw the application actually happen, contains pesticide residues or environmental contami there has been known use of this insecticide on neigh nants that exceed the Food and Drug Administration’s boring farms and, in some cases, overhead spraying. or the EPA’s regulatory tolerances, the certifying agent The organic farmer and/or certifier suspects contami must promptly report such data to the Federal health nation. agency whose regulatory tolerance or action level has In this case, a residue test would probably be performed. been exceeded. The certifier would determine whether the test was I cannot stress to highly the importance of identification needed. Testing in these cases is handled very seri of the ously. ♦ borders of the location you intend to spray or treat Under CFR §205.670, with pesticides, (b) The Administrator, applicable State organic programs + locations of organic farms, and governing State official, or the certifying agent may require preharvest or postharvest testing of any ♦ wind speed and direction at the time of application. agricultural input used or agricultural product to be sold, labeled, or represented as TOO percent organic,’ Other Sources of Contamination organic,' or made with organic (specified ingredients It is possible for organic products to be contaminated or food group(s))’ when there is reason to believe that without drift being the cause. The rules call this “unavoid the agricultural input or product has come into contact able residual environmental contamination” (UREC), with a prohibited substance or has been produced which is defined as “background levels of naturally occur using excluded methods. Such tests must be conducted ring or synthetic chemicals that are present in the soil by the applicable State organic programs governing or present in organically produced agricultural products State official or the certifying agent at the official's or that are below established tolerances.” certifying agent’s own expense, When residue testing detects prohibited substances at (c) The preharvest or postharvest tissue test sample levels greater than 5% of EPA’s tolerance for the specific collection pursuant to paragraph (b) of this section residue detected or unavoidable residual environmental must be performed by an inspector representing the contamination, the agricultural product must not be sold, Administrator, applicable State organic program’s labeled, or represented as organically produced. governing State official, or certifying agent. Sample integrity must be maintained throughout the chain We have seen drift from with synthetic fertilizer applica of custody, and residue testing must be performed in tions, as well. Organic farms are required to rely on farm an accredited laboratory. Chemical analysis must be practices that build fertility and soil health through the made in accordance with the methods described in the use of natural methods. Such practices include rotations, most current edition of the Official Methods of Analysis cover crops, and the application of plant and animal of the A O AC International or other current applicable materials or mined substances of low solubility. In some validated methodology determining the presence of cases, mined substances of high solubility and synthetic contaminants in agricultural products. substances are allowed if they are included on the national list of synthetic substances permitted for use in organic (d) Results of all analyses and tests performed under crop production as established in CFR §205.601, Pro this section: ducers may not use any fertilizer or composted plant and (1) Must be promptly provided to the Administrator; animal material that contains a synthetic substance not except, that, where a State organic program exists, included on the national list. all test results and analyses shall be provided to
112 ♦ 2007 Illinois Crop Protection Technology Conference What About State or Federal Emergency which have Web sites and information on regulations, Treatment Programs? as well as statistics. Under CFR §205.672, when a prohibited substance is ♦ owners of the operations on which you apply pesticides, applied to a certified operation due to a federal or state who may know if their neighbor is an organic farmer emergency pest or disease treatment program, and the or is in transition. certified operation otherwise meets the requirements ♦ regional organizations that educate organic or would- of this part, the certification status of the operation be organic farmers. There are several in the Midwest. shall not be affected as a result of the application of the Attending sessions at any of the organic conferences prohibited substance, provided that “(a) any harvested or those that include organics is a great way to extend crop or plant part to be harvested that has contact with your knowledge of how to prevent accidents and reduce a prohibited substance applied as the result of a Federal liability. or State emergency pest or disease treatment program cannot be sold, labeled, or represented as organically Whether you believe in organics or not, it is a form of produced ...” agriculture that is here to stay. From large to small, from mom-and-pop operations to the largest agri-businesses How Do We Work Together? on the planet, we see people turning this direction. More and more land is in transition or currently certified than Communicate with ever before. Part of “crop protection” must be protection ♦ certifiers, who are required by law to provide the public of organic crops from drift, just as it is protection of crops with basic information about their certified operations. in general from pests. You have the right to ask any organic certifier for a list of their clients and locations. Additional Information ♦ your state department of agriculture, which will have ♦ Appropriate Technology Transfer for Rural Areas at least a partial list of certified operations based on (ATTRA): 800-346-9140; www.attra.ncat.org cost share fund records. ♦ Indiana Certified Organic, LLC (ICOLLC): 317-539 ♦ universities that have programs for organic and sus 4317; [email protected] tainable agriculture. ♦ Independent Organic Inspectors Association (IOIA): ♦ extension offices, which may know of organic farmers 406-436-2031; www.ioia.net in their area. ♦ National Agriculture Statistics Service (NASS): ♦ U.S. government authorities such as USDA/NOP and h ttp :// www.usda.gov/nass the National Agricultural Statistics Service (NASS),
2007 Illinois Crop Protection Technology Conference ♦ 113 Is Extension Delivering Relevant and Effective Integrated Pest Management ...... Corn and Soybean Programs? Wendy Wintersteen
n the fall of 2003, Iowa State University s College of The survey asked growers and certified crop advisers to Agriculture asked for statewide feedback in a review provide sources they used for crop production information, of the Iowa Agriculture and Home Economics Expert then followed up with questions to evaluate Iowa State mentI Station—the colleges research program and the University's performance. Two findings are particularly associated extension programs. The college used results relevant to the development of ISU's new Corn and of the review to guide budget decisions and allocations Soybean Initiative: for future research. ♦ Both growers and CCAs rely on multiple sources for One critical priority that emerged from the review was information on corn and soybean production. For the importance of keeping Iowas farmers competitive growers, the vast majority (more than 90%) identify and profitable, a theme reflected in the colleges current private-sector crop advisers as a primary source of strategic plan. information,... Because corn and soybeans are central to farmers success + ... while most of the crop advisers (more than 80%) in Iowa, the college began to develop an initiative to identify Iowa State University as their primary source bring new focus to the needs of crop growers. Prior to of information. the official start-up of the Corn and Soybean Initiative Overall, the survey results clearly reflect the emphasis (CSI), the college surveyed corn and soybean growers and Iowa State has placed for more than three decades on agribusiness professionals to better assess key research Training the trainer—taking advantage of existing part priorities and perceptions about information and educa nerships with private agribusinesses to effectively deliver tion delivery. science-based production information to growers. This university-private sector partnership greatly multiples Highlights of the Survey the impact of ISU research and continues to successfully The 2004 survey involved telephone interviews with 400 and effectively reach farmers with needed information randomly selected corn and soybean growers and 100 and programs. certified crop advisers (CCAs), The grower interviews Survey respondents were also asked what corn and were dispersed to provide a balance among Iowas nine soybean issues needed more research attention. Disease crop reporting districts. The growers farmed an average management and insect management were rated the of 1,579 acres of corn and soybeans in 2003. The CCAs highest in both groups. Growers and CCAs were asked are professionals working for a variety of agribusinesses. whether they felt that ISU was moving in the right direc They include fertilizer/agricultural chemical dealers, tion in providing useful information, in being responsive cooperative employees, seed dealers, independent crop to their needs, and in being objective. In usefulness of consultants, seed company representatives, and farm information, 85% of growers and 84% of CCAs felt that managers. ISU was moving in the right direction. In responsive-
1 1 4 ♦ 2007 Illinois Crop Protection Technology Conference ness, 83% of growers and 76% of CCAs felt that ISU By coordinating Iowa State University’s research and was moving in the right direction. In objectivity, 86% of extension programs with commodity and farm orga growers and 63% of CCAs felt that ISU was moving in nizations’ efforts, other academic institutions, state the right direction. and federal agencies, and allied groups, the Corn and Soybean Initiative leverages resources that benefit corn Finally, respondents were asked to assign a grade to how and soybean producers. The initiative has designed specific well ISU was providing them with the information and and formal partnership programs for different groups, support they needed to be successful in their corn and organizations, or segments of the agriculture industry, soybean operations or businesses. O f the growers, 77% with a specific focus on retail agribusinesses. A formal assigned a grade of A or B. O f the CCAs, 85% assigned agreement is signed between the partners and the Corn a grade of A or B. Those who did not assign an A were and Soybean Initiative. asked to suggest how ISU could improve its grade. For both groups, the most frequently mentioned comments The Corn and Soybean Initiative partnership program were be more responsive, change research focus, and be agreement for retail agribusinesses is summarized more up to date. below. The retail agribusiness receives Planning and Development of the Initiative ♦ direct input into CSI’s applied research agenda (a special, day-long retail partners’ meeting with CSI The results of the survey have been used to guide Iowa representatives); State University in planning and development of its new Corn and Soybean Initiative. The initiative has been ♦ a privileged line of communication and access through designed to improve responsiveness to partners questions its own “partnership manager’’ (the partnership and concerns; provide a better research focus; enhance manager is an ISU staff person who is responsible communications; and position Iowa State as a leading for the retail agribusiness’s CSI partnership relation source for objective, science-based information to help ship); corn and soybean growers thrive. ♦ priority with campus and field staff through the part The mission of the ISU Corn and Soybean Initiative is nership manager; to provide science-based crop production information to ♦ the benefits of CSI marketing and promotion—viewed Iowa corn and soybean growers to increase their produc by industry, farmers, and public as being part of the tivity and global competitiveness, while also conserving right way to farm; the environment. The goals of the initiative are to ♦ day-early e-mail about all CSI information releases; ♦ be the central access point for Iowa State University and research and extension programs related to corn and soybean production; ♦ priority on any applied research that the individual retail partner helps fund, along with branding of coopera ♦ serve as an interdisciplinary catalyst to integrate Iowa tive applied research funding (results are reported as State University resources that serve corn and soybean the “[company name]/CSI applied research project," producers and related industries; which provides higher credibility with the business’s ♦ develop meaningful public/private partnerships to growers. accomplish its mission; The retail agribusiness agrees to ♦ integrate Iowa State University research and extension ♦ post CSI metal signs at all locations; resources, expertise, and programs with those of com modity, agricultural, and government organizations to ♦ assign one person to be the lead to meet and com maximize opportunities; municate with the CSI partnership manager; ♦ anticipate emerging technologies and issues that will ♦ be a conduit for delivering the CSI messages to affect corn and soybean production; and growers; ♦ provide practical, research-based information and ♦ “identity preserve (IP)” CSI information in all company education about these issues to producers. Web sites, newsletters, etc.;
2007 Illinois Crop Protection Technology Conference ♦ 115 ♦ co-host with ISU a CSI educational meeting for partners with the new initiative. More than 20 retailers growers managing more than 1,000 acres; and signed on prior to the December conference, and the initiative currently has 28 retailer partners. In addition, ♦ agree to use the CSI logo according to guidelines (not organizational partnerships have been established with changing the colors or proportions). the Agribusiness Association of Iowa, Iowa Certified The Corn and Soybean Initiative was launched in Crop Adviser Board, Iowa Corn Growers Association December 2004 at the Iowa State University Integrated and Promotion Board, Iowa Farm Bureau Federation, Crop Management Conference. Prior to the conference, Iowa Farmer Today, Iowa Soybean Association, Iowa agricultural retailers across the state were personally Crop Improvement Association, Midwest Ag Journal, visited and asked whether they wanted to be formal and Wallaces Farmer.
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