The first-ever soybean rust in Virginia was confirmed in Chesapeake and Suffolk counties in the southeast part of the state today. And with rust in five more Arkansas counties, the U.S. total is 163 positive counties and parishes in 15 states.



According to the Virginia state commentary on www.sbrusa.net,



"Asian soybean rust was detected from samples collected on Oct. 10 from a commercial field in Chesapeake and from the Suffolk sentinel plot. After incubating the leaves for three days in moisture chambers, Pat Phipps examined the leaves under a stereoscope on Saturday, Oct. 14."



The USDA confirmed this first find of the disease in the state this morning, as is required in the soybean rust monitoring program.



"The Chesapeake sample of 100+ leaflets showed only seven leaflets with pustules, ranging from one per leaflet up to 7 or 8 per leaflet. Most (in the Chesapeake sample) had either one or two pustules. The Suffolk sample of 100+ leaflets had pustules on only two leaflets; two on one leaflet and one on another leaflet. Samples from Southampton County were negative for soybean rust."



"Soybeans in the R6 development stage (full-sized seeds in the pods) will probably mature normally before rust affects a significant amount of the leaf surface. Full-season soybeans in Virginia are now being harvested; unharvested soybeans are in the R7 (physiological maturity) or R8 (mature) stages. All double-cropped soybeans have reached the R6 stage. Therefore, the likelihood of soybean rust reducing yield in Virginia in 2006 is very low.



"Although Virginia is no longer at risk to soybean rust, we will continue to scout and track the movement of the disease through the Commonwealth."



Reasons to keep scouting



"There is still much to learn about this disease. Ideally, we would like to be able to predict where the disease will occur and how severe it will be," said Erik Stromberg, Virginia Tech plant pathologist located at Virginia Tech in Blacksburg, in a commentary on the Virginia Asian Soybean Rust Home page. Models are currently being developed to do just this, and the data provided by Virginia and other states will be used to validate the accuracy of those models.



"Our goal in the few remaining weeks will be to sample double-cropped soybeans for rust in other counties to determine the scope of incidence," Phipps said. "These data, along with hourly environmental data from our weather network, should be very helpful in understanding the epidemiology of soybean rust this year and developing predictive models for the future."



Arkansas reports a dozen counties on first day of rust



This afternoon, Arkansas added five more positive rust counties to its list: Arkansas, Drew, Lawrence, Monroe and St. Francis. Arkansas total is now 12 positive counties in 2006. The only other rust in the state was found in late November, 2004, in Crittendon County.



[Editor's note: No state commentary has yet been posted on www.sbrusa.net for Arkansas. We will provide it when it becomes available.]



SOURCE: Article on StopSoybeanRust.com based on state commentaries and maps on www.sbrusa.net; Virginia Asian Soybean Rust Home page.