UNIVERSITY PARK, Pa. – With Few Sightings In The United States This Year, Asian Soybean Rust Is Spreading More Slowly Than Expected. But A Plant Pathologist In Penn State's College Of Agricultural Sciences Says This Is No Time To Lessen Vigilance Against The Disease.

First found in the United States in late 2004, Asian soybean rust is an aggressive fungus capable of inflicting multi-million-dollar losses on the nation's soybean crops. After an early appearance in Florida in late February, the disease has made surprisingly little progress, thanks to cool nights and dry daytime weather. But the risk to northern soybean production regions this season remains largely unpredictable, according to Erick De Wolf, assistant professor of plant pathology, who says it's crucial that farmers examine their fields closely for the next few months.

"The critical time for scouting is when the plants enter their reproductive stage -- when they're starting to flower," he says. "These growth stages are critical time for canopy closure and for disease development. In Pennsylvania, crops are probably reaching critical stages in late June or early July. Scouting should continue through July and a good part of August, and potentially in some areas of Pennsylvania into September."

If soybean rust is caught in its earliest stages, De Wolf says, the disease's advance can be slowed or halted by fungicide applications. So it's vital that farmers be out in their fields often, scouting for visual signs of the disease. An intensive routine can make the difference between a successful crop and devastating losses.

"The scouting procedures we're recommending would be at least every seven days," he says. "Growers should walk through the field in a zigzag or 'W' shape, covering as much area as they can and stopping at multiple places to assess groups of plants.

"In total, we'd suggest that they assess at least a hundred plants, looking for disease at all the different leaf levels within the canopy. They may have to pull the plant and look at the lower leaves in particular for signs of the disease."

A U.S. Department of Agriculture Web site, http://www.usda.gov/soybeanrust, features current updates on the location, extent and severity of rust outbreaks, provides soybean rust appearance forecasts, offers county-level tracking of disease status, connects growers to local extension offices for advice and links to other Web sites to give producers effective disease management options.

De Wolf says the Web site includes text-based narratives to help producers understand what the complex aerobiological forecasting models mean for their specific locations.

"The USDA has allowed the state specialists to provide information that's specific for their state," he says. "As the state specialist for Pennsylvania, I will be responsible for filtering the information provided by USDA researchers and synthesizing that into information that can be used by the growers here in Pennsylvania.

"I would suggest that farmers monitor the Web site for information being posted by the state specialist. That site can zoom down to your home state and offer information tailored to your state's disease forecast and weather conditions."

One tool De Wolf recommends for soybean growers this summer is a high-quality, hand-held lens or loupe, available from scientific supply outlets or photo supply stores. He says every producer needs one with at least 20X magnification to see Asian soybean rust during in-field inspections.

###

Writer-Editor: Gary AbdullahOffice 814-863-2708 FAX 814-863-9877