During 2007 an Asian soybean rust spore monitoring project was implemented by researchers at Virginia Tech. Spores are passively collected in traps during rainfall events. These traps were place at a total of 5 locations:  Eastern Shore Agricultural Research and Extension Center (AREC), Tidewater AREC, Eastern Virginia AREC, Northern Piedmont AREC) and the Virginia Tech Kentland Farm in Montgomery County. A real-time PCR (polymerase chain reaction) assay was used that can detect as few as 1 to 2 soybean rust spores on collected rain trap filters. This protocol was developed by Charlie Barnes, University of Minnesota, and Les Szabo, USDA-ASR and was a modification of a PCR assay developed by Frederick et al., 2002 (Frederick, R. D., snyder, C. L., Peterson, G. L., and Bonder, M. R. 2002. Polymerase chain reaction assays for the detection and discrimination of the soybean rust pathogens Phakopsora pachyrhizi and P. meibomiae. Phytopathology 92: 217-227).

 

A national soybean rust spore monitoring effort was already underway during 2006 and was expanded in 2007. During 2007 particpants included research groups from USDA-ARS Cereal Disease lab; NADP, Illinois Water Survey, University of Illinois; University of Arkansas; University of Minnesota; Ontario Ministry of Agriculture; and Virginia Tech.  

 

The following image shows locations of positive Asian soybean rust spore trapping results from 8/7/07 through 9/25/07, during which time all of the Virginia 2007 positive trap results occurred. Several types of spore collectors were used throughout the U.S. and Canada. (green squares=passive rain traps, red triangles= active rain traps, black circles=passive air traps). Results from the passive and active rain traps can be interpreted with more confidence, however, since spores are identified by real-time PCR, whereas spores collected by the air passive traps are identified only by their morphology. Spores collected on traps may or may not be viable (i.e. able to germinate and cause disease).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Asian soybean rust spores were identified from passive rain traps at the Eastern Virginia AREC on 8/6/07 and 8/27/07 and at the Tidewater AREC on 8/7/07. Spore monitoring from the five passive rain traps in Virginia ended in early October 2007. Soybean rust was first identified in Virginia in 2007 in Isle of Wight County on October 19, 2007 after the crop was no longer at risk of yield loss.