Virginia's Current Recommendation and U.S. Tracking Info

Geographic Movement of Asian Soybean Rust

Survival, Movement & Development of Asian Soybean Rust

Forecasting Plant Disease Epidemics

See the USDA-PIPE website  for national commentary and more information. 

  

 

 

The rust fungus, Phakopsora pachyrhizi, that causes Asian soybean rust has caused serious crop losses for decades in the eastern hemisphere. During the 1990’s Asian soybean rust was identified in Hawaii and Africa. In 2001 it was found on soybeans in Paraguay, South America. Later it was identified in Argentina, Bolivia, Brazil, Paraguay, and Uruguay. In November 2004 Asian soybean rust was identified from soybeans in a research plot in Louisiana. Subsequently that year Asian soybean rust was identified in Alabama, Arkansas, Georgia, Florida, Mississippi, Missouri, South Carolina and Tennessee. See the Virginia Soybean Rust and Aphid Monitoring Program page for more historic info on movement of the soybean rust fungus.

 

 

 

Asian soybean rust requires a living host for survival. This makes survival of the fungus in areas with temperatures below freezing unlikely. However overwintering in areas with freezing temperature is possible if the fungal host is located in a microclimate that is more protected. For example, overwintering of Asian soybean rust did occur during the winter of 2005/2006 in Georgia where the fungus was found on kudzu located in protected urban locations.

 

Fungal rusts, such as Asian soybean rust, have spores that are readily windborne and able to move long distances by wind currents. These spores are produced prolifically in multiple cycles during the growing season when environmental conditions are favorable. These qualitites contribute to Asian soybean rust's potential for epidemic disease development and allow long-distance movement into new areas despite the fact that rust is unlikely to overwinter where freezing temperatures occur.

 

Conditions optimal for disease progress are moisture on the leaf surface from periods of 6 to 12 hours and temperatures from 59° to 82°  F—conditions typically experienced in Virginia during the soybean growing season. 

 

 

 

Weather and climate are key factors in movement and survival of many fungal plant pathogens, such as Asian soybean rust. The North American Plant Disease Forecast Center at North Carolina State University uses the expertise of meteorological scientists and plant pathologists, along with disease reports from growers, to determine the potential for epidemic disease development. The North American Plant Disease Forecast Center has been forecasting disease epidemics of tobacco blue mold and cucurbit downy mildew since the late 1990's and these forecasts are widely used by plant pathologists and growers today. Forecasts for soybean rust will be generated  by the North American Plant Disease Forecast Center on Monday, Wednesday and Friday of each week from March through October. Specifics on how to read the soybean rust forecasts are detailed at their website.

 

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