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News Releases
| DATE: | February 25, 2005 | | CONTACT: | Mark Condon | | | (703) 837-8140 |
Information and Reference Guide for Managing Soybean Rust SITUATION
Soybean rust (SBR) Phakospora pachyrhizi was introduced into the continental United States in the fall of 2004, presumably as a consequence of tropical storm activity. Model predictions indicated that soybean rust was widely dispersed throughout the southeastern United States, and subsequent field and laboratory observations confirmed this distribution.
USDA’s RESPONSE
USDA is facilitating the development of a federal/state/industry coordinated framework for surveillance, reporting, prediction, and management for the 2005 growing season. The cooperating USDA agencies include the Cooperative State Research Extension and Education Service (CSREES), the Agricultural Research Service (ARS), and the Animal Plant Health Inspection Service (APHIS).
The goal of the framework is to provide stakeholders with effective decision support for managing soybean rust during the 2005 growing season by.
1. Delivering a surveillance and monitoring network to provide timely information of the incidence and severity of soybean rust in the United States, Caribbean basin, and Central America.
2) Providing a web-based system (USDA Soybean Rust Monitoring and Prediction System) for disseminating distribution information, forecasts, and decision criteria to stakeholders.
3) Developing decision criteria for fungicide application, and
4) Providing predictive modeling of aerial transport of SBR spores from active source regions to soybean growing areas in the U.S.
USDA Efforts to Monitor and Predict Soybean Rust
USDA efforts to monitor and predict the distribution of soybean rust follow previous APHIS efforts to prevent the introduction and establishment of exotic pests. They are:
CAPS Program - The APHIS Cooperative Agricultural Pest Survey (CAPS) program conducts annual surveys for exotic pests with national, regional and state targets. The CAPS program has supported a number of novel techniques and methods for pest survey and detection.
NAPPFAST - In 2002, APHIS in association with North Carolina State University sponsored the development of the NCSU APHIS Plant Pest Forecast System (NAPPFAST). The NAPPFAST system uses biological models, climate and other GIS data layers to forecast pest occurrence.
NPDN - CSREES/USDA set up the National Plant Diagnostic Network (NPDN), a network of Land Grant University and State Department of Agriculture plant disease and pest diagnostic clinics across the United States. The NPDN allows diagnosticians, state regulatory personnel, and first detectors to communicate efficiently information, images, and methods of detection in a timely manner.
IAMS - In 2003, APHIS and CSREES began the development of the Integrated Aerobiological Modeling System (IAMS), which was designed to track the aerial movement of invasive pests and focused on tracking the off- shore movement of soybean rust.
SRAPS - In late 2004, following the first detection of soybean rust in the continental United States, the IAMS system was modified to create a specialized system focused solely on soybean rust – the Soybean Rust Aerobiology Prediction System (SRAPS). This pest forecasting innovation laid the information technology foundation for the USDA framework. The SRAPS will provide information for locating strategic sites to monitor for soybean rust incidence and severity
International
Monitoring - International monitoring efforts are being coordinated by the Agricultural Research Service (ARS)/USDA. The focus of international monitoring will be on Mexico and the Caribbean, with particular emphasis on regions which may provide a source of wind-blown rust spores early in the Northern Hemisphere growing season that could impact the US on an annual recurring basis.
USDA Soybean Rust Monitoring and Prediction System
USDA is working with universities and private consultants in developing web site to disseminate decision criteria, observations of soybean rust, and predictive model output to stakeholders that will be available to the public and stakeholders (currently expected to be operational March 2005). The USDA web site, “Soybean Rust Monitoring and Prediction System” will:
• Feature a user interface which is zoomable from the national to the sub-county scale.
• Contain a calendar to allow users to see the progression of disease severity and crop greening on a day by day basis. It will also allow the user to move forward or backward in time. Individual or multiple days can be selected.
• Display observations on the map using symbolic and color coding. Symbolic coding (e.g. +, o,, ∆) will distinguish observations from different protocols (e.g. sentinel, mobile, NPDN and industry). Color coding will be used to distinguish absent, present (unconfirmed), present (confirmed) and disease severity.
• A protocol will be established for the confirmation of observations. Primary confirmation is provided by observations collected using the mobile, sentinel and NPDN protocols. Industry observations will be displayed on the above-mentioned map as confirmed if they appear in the same state and contiguous predicted severity zone as a confirmed primary observation. Industry observations will also be displayed if they have been confirmed by PCR analysis.
• The system will display observed and predicted disease severity and spore deposition. Predicted disease severity will be shown as a color scale from nil to severe based upon the proportion of diseased leaf area. Latent infections (those that have not yet appeared) will also be indicated on the color scale. The predicted and observed severity will use the same color coding scheme.
• The website will have reference overlays include roads, crop commodities and county boundaries.
• The web interface will include forms for data entry and report generation.
• Interpretations of the maps will be provided by an ARS national specialist. When a user clicks on an individual state, an interpretation from the state designated soybean specialist will also appear.
Decision Criteria for Fungicide Application
Fungicides will be the primary tools in the management of soybean rust in the United States. Guidelines for managing the disease are based on data from Africa and South America where it was found that the crop should be protected from the flowering stage through the grain fill stage. The most effective management programs were those that were preventative: that is, where the first application was applied before soybean rust was seen in the field. The efficacy of the products available in the U.S. (under either Section 3 or Section 18 registration) has been proven in trials in South America and Africa. The products that have proven efficacy include chlorothalonil, strobilurin and triazole products.
Each product has different strengths and weaknesses and they differ in how and when they should be used to manage soybean rust. None of the products can eradicate the fungus. The triazole products have curative active (can inhibit but not eradicate existing infections) while the chlorothalonil and strobilurin products are protectants and only prevent new infections. The chlorothalonil and strobilurin products need to be applied before infection, and once the disease exceeds 1% incidence, yield losses may occur even with a subsequent application of a strobilurin product. Triazole products can be applied after disease appearance, but once the disease is at a 10% incidence or is in the mid-canopy, yield loss will be expected.
Monitoring will be critical in the decisions of when and what fungicides to apply. Predictive forecasting, although in its first year of validation and testing may also provide useful data for decision making. Based on experience in South America and South Africa, a typical management program may require two application of fungicides based on phenology of the plant at the reproductive growth stages. The first application is at growth stage R1-R2 and the second 14 to 20 days later. The program could also be based on a calendar with the first application at 50 days after planting and the second 14 to 20 days later. Monitoring data and predictive forecasts could be used to time fungicide applications, thus possible delaying the first application and/or eliminating the second.
Factors that influence fungicide use include:
• Soybean rust is a rapidly spreading disease. Studies in Africa and South America have demonstrated that fungicides need to be applied before or as soon as the disease is detected in a production field.
• Late diagnosis of the disease will likely result in substantial crop loss. If heavy spore deposition occurs along with spore germination and colonization, it may be too late to effectively control the disease.
• Crop loss may occur if fungicides are applied late and few curative fungicides are available.
• The disease is difficult to observe and can be mistaken for other disorders or diseases.
• Soybean rust treatments should be applied at approximately 50 days after planting and 14 to 20 days later. An application should only be missed if disease was absent from the production area. If spore showers are likely then these treatments are essential regardless of whether disease has been yet observed in the actual farmer’s field.
• By using ground-truthed prediction models there is potential to provide decision information to producers and other decision makers well before disease is observed in local fields and in time to apply timely and effective fungicide treatments.
Additional information on fungicides for soybean rust can be found at: http://jump.jbnimble.com/pioneer/ci/ci25.pdf and http://www.ncpmc.org/NC504/LevyExperiment301152.pdf
Fungicide Application Guidelines
The National Soybean Rust Working Group (NC 504) is developing a manual containing guidelines for effective fungicide application to manage soybean rust. Reportedly, this manual will be available March 2005. The website for the National Soybean Working Group (NC 504) is located at: http://www.ncpmc.org/NC504/
Information on fungicide application for soybean rust can also be found as a PDF of Crop Insights, Asian Soybean Rust: Fungicide Application Technology at: http://jump.jbnimble.com/pioneer/ci/ci24.pdf
Predictive Models
Following is a summary of work being conducted by government agencies and universities in developing predictive models for soybean rust. More specific information and a link to these forecasts will be available from the USDA web site - Soybean Rust Monitoring and Prediction System (expected March 2005).
• The Soybean Rust Aerobiology Prediction System (SRAPS) is collaborative project between Penn State University, North Carolina State University, and the information technology company ZedX, Inc.
• The Soybean Rust Prediction System (SRPS) displays predicted rust severity at a 10 km2 resolution across North America. The components of the (SRPS) model include:
(i) Source area delineation based on soybean crop and kudzu distributions
(ii) Over wintering survival of rust in source areas
(iii) NDVI-calibrated, temperature-driven greening function for North America
(iv) An evaluation of spore aerial transport potential using pressure, wind and temperature fields with 6 hour resolution and corresponding cloud cover and precipitation records
(v) Soybean crop growth model driven by daily temperature and precipitation data from past 5 years, and
(vi) Soybean rust epidemiology model driven by daily temperature and leaf wetness data from past 5 years. Observations primarily from sentinel plots will be used to quantify the distribution of spore production in domestic and off-shore source regions. The system will display observed and predicted disease severity and spore deposition. Predicted disease severity will be shown as a color scale from nil to severe based upon the proportion of diseased leaf area. Predicted latent (infected but not yet appeared) will also be a severity class. The predicted and observed severity will use the same color coding scheme.
• The North American Disease Forecast Center (NCSU) will also provide disease forecasts using the HYSPLIT modeling system. The forecasts will be similar to those it has provided operationally for nine years.
• Iowa State University is also in the process of developing forecast models and will participate in the national forecasting efforts. Predicted daily weather data from an atmospheric model (MM5) will be used as inputs to make short term prediction of soybean rust risk in different geographic areas.
Plant Hosts Other than Soybean
Phakopsora pachyrhizi infects over 95 species of plants from more than 42 genera, including soybean and related Glycine species. The full host range of both rust species has not been clearly identified and may be complicated by pathotypes and differential reactions within host species. The broad host range of the two species of Phakopsora that infect soybean is unusual among rust pathogens, as most rust species have a narrow host range that is limited to a few plant species. The large number of host species increases the likelihood that this pathogen will survive and over winter in the southern U.S., as well as in Central America.
A complicating factor for pest detection and control are the large number of legume
hosts that can harbor soybean rust. One widespread host in the United States is kudzu, Pueraria montana var. lobata, that could serve as a reservoir for soybean rust. There are a variety of other important hosts that are leguminous crops or weeds that have shown varying degrees of susceptibility to both species of Soybean rust. Some other common hosts are yellow sweet clover (Melilotus officinalis), vetch (Vicia dasycarpa), medic (Medicago arborea), lupine (Lupinus
hirsutus), green and kidney bean (Phaseolus vulgaris), lima and butter bean (Phaseolus
lunatus), and cowpea or backeyed pea (Vigna unguiculata).
As most if not all state Section 18 fungicide approvals for soybean rust apply only to soybeans, seed companies should consult with crop protection companies or state extension agencies for recommendations of fungicide application for the leguminous plant host other than soybean.
Personnel Movement from Rust Infected to Non-Rust Infected Areas
Even though Soybean Rust has been confirmed in the United States, USDA strongly recommends that citizens still take every precaution when moving from rust infected areas to non-rust infected areas (international and domestic) to limit spore dispersal. Therefore, seed industry personnel are encouraged to review and follow the recommendations contained in the document entitled, “Limiting International Movement of Plant Pests.” This document is available through the ASTA website at http://www.amseed.org/newsDetail.asp?id=96.
Movement of Leaf or Pathogen Samples
APHIS reports that industry may soon have the ability to move leaf and pathogen samples for diagnostic or other purposes under its permitting process. To obtain permits and confirm specific conditions for movement of samples, please go to: http://www.aphis.usda.gov/ppq/permits/plantpest/ or call an APHIS permits staff person at: 1-877-770-5990
Other Important Information Relative to Soybean Rust including Reference Web Sites
1. The Plant Diagnostic Information System (PDIS) to alert producers and provide an access point for current incidence maps is located at (www.pdis.org)
2. Samples for soybean rust diagnosis should be sent to appropriate State Department of Agriculture’s diagnostic service or the land grant university’s diagnostic laboratory in the state in which the sample was collected. Do not send suspect samples directly to the USDA Beltsville laboratory. State Department’s of Agriculture contacts are available at the National Plant Board website: http://www.aphis.usda.gov/npb/npbmemb.html. A list of university diagnostic laboratories is available at the American Phytopathological Societies directory website: http://www.apsnet.org/directories/univ_diagnosticians.asp
3. This National Site contains complete Crop Profiles and Pest Management Strategic Plans databases on Soybean Rust including IPM Expertise database, information on pesticide efficacy and use, current pest management research, funding opportunities, and links to many related sites: www.ipmcenters.org or http://www.ipmcenters.org/NewsAlerts/soybeanrust/ or http://www.ncipm.org/soybeanrust or http://www.ncpmc.org/soybeanrust/index.html
4. For multi-faceted information on soybean disease information, please consult http://www.soydiseases.uiuc.edu/index.cfm. The Laboratory for Soybean Disease Research employs state-of-the-art laboratory, greenhouse, and field research methodologies to soybean disease epidemiology, soybean pathogen variability, and soybean host resistance.
5. The website for the North American Plant Disease Forecast Center is www.ces.ncsu.edu/depts/pp/soybeanrust
6. For updated news releases and other information announced by APHIS, please go to: http://www.aphis.usda.gov/lpa/issues/sbr/sbr.html
7. For timely news and information on soybean rust, please go to http://www.stopsoybeanrust.com
8. To view past APHIS seminars on Soybean Rust, please go to:
Dec 15 webinar
http://w.on24.com/r.htm?e=10061&s=1&k=DF1D55B02B8F6AED7FFF70F4460DCFF1
Jan 19 webinar
http://w.on24.com/r.htm?e=10357&s=1&k=4C3C03EB8B0873090C0A71AF8A33BB99
9. The American Phytopathological Society website on soybean rust can be located at: http://www.apsnet.org/online/feature/rust/
10. Some individual state newsletters and information on soybean Rust can be found at:
Iowa - http://www.ipm.iastate.edu/ipm/icm/
Indiana - http://www.entm.purdue.edu/entomology/ext/ext_newsletters.html
Florida - http://www.doacs.state.fl.us/pi/enpp/pathology/soybeanrust.html
Illinois - http://www.ag.uiuc.edu/cespubs/pest/articles/200213k.html
Ohio - http://ohioline.osu.edu/ac-fact/0048.html
Wisconsin - http://www.uwex.edu/ces/ag/issues/soybeanrust/
Missouri - http://muextension.missouri.edu/explore/agguides/crops/g04442.htm
Michigan - http://www.michigan.gov/mda/0,1607,7-125-1568_2390_34505---,00.html
North Dakota - http://www.ag.ndsu.nodak.edu/extplantpath/Soybean%20Rust/Soybean%20Rust.htm
Kentucky - http://www.ca.uky.edu/agcollege/plantpathology/PPAExten/SoybeanRust.htm
North Carolina - http://ipm.ncsu.edu/
11. For policy on Fed/State identification please see:
http://www.aphis.usda.gov/ppq/ep/soybean_rust/2-10policy.pdf
### Founded in 1883, the American Seed Trade Association (ASTA), located in Washington, DC, is one of the oldest trade organizations in the United States. Its membership consists of about 900 companies involved in seed production and distribution, plant breeding, and related industries in North America. As an authority on plant germplasm, ASTA advocates science and policy issues of industry importance. Its mission is to enhance the development and free movement of quality seed worldwide.
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