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Soybean Rust Management in the Mid-Atlantic Region

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Soybean Rust Management in the Mid-Atlantic Region Soybean Rust Management in the Mid-Atlantic Region 2006 2007 Underside of leaf heavily infested with soybean rust. Lesions with multiple pustules. Enlarged view of lesion on underside of a leaf showing multiple pustules per lesion. Cover maps downloaded from http://www.sbrusa.net/. Red indicates counties where rust has been found. Green indicates counties which have been scouted but no rust was found. Inside cover photos courtesy of J. T. Yorinori, Ph.D., Embrapa Soja, Londrina, Brasil. The use of trade names in this publication is intended for the purpose of clarity and information. Inclusion of a trade name does not imply approval to the exclusion of other products, which may be of similar composition. Clemson University does not guarantee or warranty the products named. The Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, sex, religion, national origin, disability, political beliefs, sexual orientation, marital or family status and is an equal opportunity employer. Clemson University Cooperating with U.S. Department of Agriculture and South Carolina Counties. Issued in Furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of May 8 and June 30, 1914. Soybean Rust Management in the Mid-Atlantic Region Edited by: John D. Mueller Stephen R. Koenning Robert C. Kemerait, Jr. Patrick M. Phipps Copyright © 2008 by Clemson University Extension Service, North Carolina State University Cooperative Exension, South Carolina Department of Agriculture, South Carolina Soybean Board, Virginia Cooperative Extension, and the University of Georgia Cooperative Extension. All rights reserved. This publication or parts thereof may not be reproduced in any form without written permission of the publishers. Introduction The soybean checkoff is proud to partner with your cooperative extension and research special- ists to bring you this updated version of Soybean Rust Management in the Mid-Atlantic Region. This publication contains the most current, accurate, and concise information based on factual observations by researchers who have studied rust behavior and movement over several grow- ing seasons here in the southeast. Much of the research conducted in order to make the recom- mendations found in this guide was funded, in part, by your soybean checkoff. We hope this information will assist in your decisions as you strive to become more productive and profit- able. Three years after throwing Asian Soybean Rust into the soybean management mix, several questions have been answered and theories have been developed. The sentinel plot monitoring system has worked very well. As rust spreads, most of the first finds are in sentinel sites. Rust has not been a problem prior to flowering – therefore, applying fungicides before the R3 growth stage is not recommended unless pressure is severe. Timing applications of appropriate fungi- cides is very important both in protecting a crop and saving money by eliminating unnecessary sprays. Untreated test plots have shown yield reductions, but yield losses in properly treated commercial fields have been minimal. While rust is known to have over ninety-five host spe- cies, including kudzu and legume crops, it has not affected either vegetable production or wild- life food plots. Finally, rust spores seem to be very susceptible to ultraviolet rays and extreme heat – several years of drought and fairly inactive hurricane seasons have quite possibly slowed the incidence and severity of rust. The best decisions are made with the most information. This wisdom applies to protecting your crop from soybean rust, so be proactive, prepare, and have a plan before hooking up to the planter. Know your soil, plant varieties, soybean growth stages, short and long-term weather forecasts, and the budget within which you are working. Prepare for other perennial pests and nutrient requirements, as healthier plants are less susceptible to disease in general. Use this book, the USDA Soybean Rust website, attend grower meetings, and stay informed. Five years ago the soybean checkoff funded the first research in the U.S. to identify rust-resis- tant soybean varieties. So far, two genes have been identified that could lead to rust resistance in the near future. Additional work is being conducted to develop new fungicides and evaluate alternative management techniques. Your checkoff is committed to building a strong future for soybean farmers. You can always count on your cooperative extension service professionals and your farmer-leaders to work together in making your checkoff payoff. Aaron Wood Executive Director South Carolina Soybean Board State of South Carolina Department of Agriculture Hugh Weathers Commissioner Contributing Authors Jim Dunphy Dan Phillips North Carolina State University University of Georgia – Griffin [email protected] [email protected] David Holshouser Steve Rideout Virginia Tech Virginia Tech Tidewater A.R.E.C. – Suffolk Eastern Shore A.R.E.C. - Painter [email protected] [email protected] David Howle Hunt Sanders Clemson University University of Georgia - Tifton [email protected] [email protected] Phil Jost Layla Sconyers Formerly University of Georgia Formerly University of Georgia Bob Kemerait Erik Stromberg University of Georgia – Tifton Virginia Tech [email protected] [email protected] Steve Koenning Pawel Wiatrak North Carolina State University Clemson University [email protected] Edisto R.E.C. [email protected] John Mueller Clemson University Aaron Wood Edisto R.E.C. South Carolina Soybean Board [email protected] [email protected] Pat Phipps John Woodruff Virginia Tech University of Georgia - Tifton Tidewater A.R.E.C. - Suffolk [email protected] [email protected] Soybean Rust Management Plan Table of Contents Introduction A Brief History of Soybean Rust in the Western Hemisphere 1 - 10 Asian Soybean Rust in Georgia Asian Soybean Rust in South Carolina Asian Soybean Rust in North Carolina in 2007 Asian Soybean Rust in Virginia Soybean Rust Identification and Life Cycle 11 - 14 Symptoms on Leaves Overwintering Other Crops and Weed Hosts Commonly Found in the Southeastern United States Montoring Rust Movements 15 - 16 Sentinel Plots in the Southeastern United States Value of Spore Traps in Predicting Spread Common Diseases of Soybean in the Mid-Atlantic Region 17 - 24 Examples of Common Diseases of Soybean Downy Mildew Brown Spot Frogeye Leaf Spot Cercospora Blight and Purple Seed Stain Target Spot Anthracnose Pod and Stem Blight Bacterial Blight Bacterial Pustule Examples of Soilborne Diseases of Soybean Charcoal Rot Red Crown Rot Sclerotinia Stem Rot Sclerotium Blight Agronomic facts the grower needs to know 25 - 30 Don't Panic Understanding the Growth Habit of Soybeans Table with Descriptions of Growth Stages Agronomic Considerations Fertility and pH Pest and Weed Management Consider Earlier Varities Planting Considerations Watch the Sentinel Plots Follow Rust Forecasts Final Thoughts Recommendations for Managing Soybean Rust Management of Soybean Rust 31 - 34 Avoiding Rust Spraying Fungicides When You Should Spray for Rust Disease Tracking Reports Sentinel Plot Data Scouting Your Fields Plant Growth Stages Newsletters by State Types of Fungicides and Rates of Application Method of Application Yield Boost from Fungicides? Types of Fungicide Labels Table of Fungicides for Management of Soybean Rust Fungicide Spray Test Results 35 - 38 2005 Test 2006 Test 2007 Test Evaluation of Fungicides for Control of Asian Soybean Rust in Attapulgus, GA, 2005 Evaluation of Fungicides for Control of Asian Soybean Rust in Attapulgus, GA, 2006 Evaluation of Fungicides for Control of Asian Soybean Rust in Moultrie (Kemsoy-1), GA 2007 A Brief History of Rust in the Western Hemisphere Layla Sconyers, Post-Doctoral Research Associate, University of Georgia-CPES, Tifton Steve Koenning, Extension Plant Pathologist, North Carolina State University Rust in South America: Soybean rust was first observed in South America in 2001 in Paraguay. Since 2001 it has been found in Brazil, Bolivia, Argentina, Colombia, and Uruguay. By 2004, most of the soybean acreage in Brazil received multiple applications of fungicides. In 2005 the number of fungicide applications for soybeans in South America ranged from less than 1 in Argentina to as many as 5 in parts of Brazil and Bolivia. Rust was relatively light in many areas of Brazil in 2005-2006 because of drought, whereas other areas with abundant rain- fall saw severe pressure from rust. In parts of Brazil and Argentina fungicide applications started two to three weeks before flower- ing. Rust was widespread in Argentina in 2004-2005, but yield loss from rust was considered minimal, and Argentina had record soybean yields. Argentina was expecting severe rust in 2005-2006, because of a mild winter that resulted in large amounts of volunteer soybean that were infected with rust. Soybean rust, however, did not develop as anticipated in Argentina even in the northern states of Entre Rios and Missiones. There were periods of drought in southern Argentina that may have impeded development of rust there, but more than adequate rainfall occurred in northern areas. Some crop professionals suggested that variation in day/night temperatures south of Brazil impeded rust development. The crop consultants in Argentina take a more conservative view on management of soybean rust. In general, their recommendation is to wait until rust is found before making fungicide applications. Detection of Rust in the United
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