Penn State Contributes to Unprecedented
USDA Soybean Rust Effort

In response to the costly threat of an invasive plant disease, the U.S. Department of Agriculture has developed a national decision- support system that relies heavily on a computer-forecasting service developed by faculty in Penn State’s College of Agricultural Sciences.

Model illustrations (left to right) show the probable path of rust spores from South America through Central America and into the southern United States during Hurricane Ivan in 2004. The Web site provides a state-by-state interpretation of international aerobiological and other data and advises growers on the best specific counter-measures to take.

Asian soybean rust, an aggressive fungus capable of inflicting multimillion-dollar losses on the nation’s soybean crop, was first found in North America during late 2004 and is expected to spread throughout the soybean growing regions of our country this summer. The one-stop federal resource, on the Web at http://www.usda.gov/soybeanrust, provides up-to-date forecasts on the location and severity of soybean rust outbreaks in the United States, Caribbean basin, and Central America. It offers current surveillance reports, suggests where soybean rust is likely to appear next, offers county-level information on disease status, connects growers to disease-management guidelines developed by county-based extension educators, and provides links to other Web sites with information about this potentially devastating plant disease.

At the core of the resource is a new, interactive program developed by Penn State aerobiologist Scott Isard working in conjunction with ZedX Inc., an information technology company that specializes in the development of weather-based, decision-support products for agriculture.

“The effort is unprecedented in our nation’s history,” says Isard, a professor in the departments of plant pathology and meteorology and the driving force in the program’s development. “It is changing the way we will implement integrated pest management in the future.”

The efforts of Isard and others have resulted in an interactive Internet Web site that involves researchers, extension specialists, industry representatives, and USDA officials in tracking the development of the soybean crop, as well as the disease’s progress throughout the United States.

“This framework helps ensure that soybean producers have easy access to the most current and useful information and guidance on soybean rust,” says Erick De Wolf, Penn State plant pathologist. “ The site is probably the largest-scale effort of its kind to date. We use a similar disease forecasting system to predict head blight and head scab of wheat, but it’s nowhere near as complex or flexible as this.”

Symptoms of soybean rust are subtle and can be confused with several diseases common to Pennsylvania. Diagnostic features of soybean rust include tan to reddish-brown lesions (left) with fruiting structures rupturing through the outer layers of leaf tissue (right). Lesions tend to be angular and are restricted by leaf veins; diameter ranges from one-sixteenth to one-eighth of an inch. The federal Web site gives growers visual aids for identifying the disease and referral to local cooperative extension offices for help with diagnosis and treatment.

An important aspect of the system is the nationwide integration of local extension educators and university specialists as both providers and interpreters of the system’s data. Local observations on weather conditions and disease status are fed into a database by all states participating, allowing Isard and his ZedX collaborators to calibrate and adjust their predictive
model. “The extension educators in the threatened states are a sort of on-farm monitoring network, checking sentinel plots and production fields for the potential arrival of soybean rust,” De Wolf says. “It’s not just the faculty at Penn State and other universities, but the whole infrastructure of cooperative extension and the agricultural industry in our country that have been mobilized to respond to this challenge.”

Another unique aspect is the role of state specialists such as De Wolf in interpreting results and delivering customized guidelines to growers that take regional needs into account.

“The model provides recommendations of where to scout for the disease, as well as estimates of where and how severe the disease is in certain areas in a state or county,” De Wolf says. “The state specialist’s role is to synthesize the information from Isard and the other researchers, give it a regional interpretation, and pass that information to the public.

“In Mississippi, for instance, disease-management guidelines will be very different than in Pennsylvania,” De Wolf adds. “The crop is produced differently,so the way the model is interpreted needs to reflect the local situation. We will use model predictions in suggesting disease-management guidelines for Pennsylvania growers. The growers will read the regional information we provide, look at what’s happening in their fields, and make decisions.”

Both Isard and De Wolf laud the USDA for its proactive leadership in managing the disease by funding research projects that enabled the framework to evolve. This effort, De Wolf explains, is part of a USDA strategic plan implemented in 2002 in anticipation of a soybean rust invasion of the United States. The plan established priorities for protection, detection, response, and recovery. “

Isard and the ZedX team of programmers developed the interactive soybean rust Web site with support from several USDA agencies, including the Animal and Plant Health Inspection Service; the Cooperative State Research, Education, and Extension Service; the Risk Management Agency; and the Agricultural Research Service,” he says. “These agencies partnered with soybean industry organizations, state departments of agriculture, and many in the research and scientific communities.”

Isard also led a team of scientists from Penn State and the National Soybean Research Laboratory in Urbana, Illinois, that traveled to Paraguay this winter to study the disease. “This is the first time in history that the USDA had this kind of foresight and invested in sending a research team offshore to understand a disease before it appeared in this country,” he says. “Trying to anticipate invasive species is a new paradigm. It’s important to recognize the USDA’s proactive efforts. There was a certain amount of risk on their part if soybean rust didn’t show up, but their foresight has been vindicated.”

—Gary Abdullah