e-newsletter - fall 2007
Aerobiologist Uses Computational Models and Web-Based Information Platform to Predict Spread of Agricultural Pathogens
Asian Soybean Rust: Development of a Comprehensive Data Collection, Invasion Prediction, and Education Tool
Dr. Scott Isard, professor of aerobiology, recently led a multifaceted effort to develop an Internet platform that allows real-time tracking of the spread of the economically important pathogen Asian soybean rust. Isard is an aerobiologist--he works at the intersection of meteorology and biology to study the processes by which agricultural plant pathogens move through the air. Using Isard’s team’s predictions of pathogen spread, growers can make informed decisions about spraying vulnerable crops with fungicides, thereby increasing their operations’ profitability and reducing fungicides in the environment. Isard’s partners included private industry information technology specialists from ZedX, Inc.; state Cooperative Extension specialists; U.S. Department of Agriculture (USDA) and other scientists; and soybean growers around the country.
In 2001 winds carried soybean rust from Africa to South America, and USDA scientists became concerned about its potential spread into the United States. About 355,000 U.S. farms grow soybeans on about 72 million acres, representing about 23 percent of all crops harvested in this country. In 2005 USDA predicted that widespread infection could reduce soybean yields by 10–80 percent.
Isard quickly got to work on the pathogen. He took a team to Paraguay to learn how to scout for the rust and begin to determine where and when it was likely to spread.
Together with state Cooperative Extension specialists, Isard’s team established and began regular monitoring of “sentinel plots” of early-maturing soybean varieties across the southern U.S. These varieties become infected before most commercial fields would.
Soybean plants are most vulnerable to rust infection between sprouting and flowering, which in Pennsylvania occurs from June through August. Growers need to know about expected spore invasion during this period so they can protect their crops with fungicide, if necessary.
Asian soybean rust’s U.S. appearance came in 2004, courtesy of Hurricane Ivan. Isard’s maps of predicted landfall and spread proved to be remarkably accurate.
During the growing season, Isard and his team of experts now develop a daily soybean rust forecast of expected spread that incorporates the results of multiple models and is tweaked by human experience. The forecasting team includes three Penn State undergraduate student interns, who work with Paul Knight in Penn State’s Department of Meteorology.
Luckily, the pathogen needs a green foliage host year-round to overwinter. Currently only kudzu growing along the Gulf Coast meets this qualification, so each year its spread starts anew from these points. So far soybean rust has spread more slowly than plant pathologists had feared it would. During the 2007 growing season it did extend its reach, however, along the Atlantic coast in Virginia and even up into Ontario, just north of Lake Erie.
Isard’s research team received USDA’s Group Honor Award for Excellence, the agency’s highest honor, and the Internet platform has been and will continue to be adapted for tracking other diseases and pathogens. Isard says modestly, “All we’ve done is use information technology to link people so that they can exchange information effectively.” USDA’s Economic Research Service estimated that the integrated Web-based platform increases U.S. soybean growers’ profits by $11–300 million per year, due to savings from reduced fungicide applications.
This work was funded by the USDA’s Animal and Plant Health Inspection Service and USDA’s Cooperative State Research, Extension and Education Service Biosecurity Grant Program.
A New Threat: Wheat Stem Rust Overcomes Inbred Resistance
A new concern among plant pathologists is the recent spread from Africa into Asia of new variant of wheat stem rust that now infects cultivars that were genetically engineered to resist the pathogen. It is expected to spread in the next few years to the north and east into India and the Middle East, where it could cause widespread famine. Alternatively, the pathogen could spread to the west into South or Central America, as soybean rust did, says Isard, and later into the U.S. By adapting the Internet platform developed for soybean rust, Isard’s team hopes to model this new wheat stem rust’s predicted spread and warn growers of likely invasion, allowing them to protect their crops with fungicides. Given enough time, Isard explains, plant geneticists can breed resistance to this new threat into new cultivars. His models and IT application could help growers manage the disease until that time.
Scott Isard, Ph.D., is professor of aerobiology with a joint appointment in the Department of Plant Pathology in the College of Agriculture Sciences and in the Department of Meteorology in the College of Earth and Mineral Sciences. Ha also is a PSIEE co-hire. He can be reached at sai10@psu.edu.
by Joy Drohan