At the end of an already "rust-filled" day yesterday (9/7), Georgia officials reported finding Asian soybean rust on kudzu in three southwest Georgia counties -- all appear to be "new" infections after recent rains.

The samples, collected Sept. 5, put Grady and Thomas back as positive on the USDA observation map, filling in southwest Georgia with red again. These two counties last had rust on kudzu in early 2006, but were put back to green when those infections appeared to be destroyed, and no active rust was seen for months.

One new county, Seminole, has rust for the first time this year. Rust was found in the county on volunteer soybeans in 2005 -- the second U.S. find of 2005, but rust had not been found in this particular site since 2004, officials said.

There are now eight counties in Georgia positive for rust in 2006, all currently red (Grady was reinstated when rust appeared again in June 2006) and lined up above the rust-positive counties in Florida to the south. In 2005, Georgia ended up with 34 positive counties by year's end.

There are 41 counties and parishes that have been confirmed to have soybean rust in the United States in 2006. At this point in the season last year, the count was 55.

Georgia infections seem to be "new" after rains

According to the Georgia state commentary on, soybean rust was detected on kudzu samples collected Sept. 5 in Seminole, Grady and Thomas counties. These counties are located in southwest Georgia, bordering Florida.

"Rust was once detected in Grady and Thomas Counties during the winter months, but was believed to have been destroyed at that time," the commentary said. "These rust infections found this week seem to be 'new' infections -- possibly spores were brought in with the recent and frequent rain showers we've been having."

The rust find in Seminole County was on kudzu, and this is the first finding of rust in that site since 2004, according to the commentary.

"This is also believed to be a 'new' infection, with spores perhaps being brought in with the recent rain events. Rust was detected on all three samples with a dissection microscope on two or fewer leaves per sample (32-65 leaves per sample).

"With the recent rains and the detection of rust South Carolina, it is extremely important that everyone continues to scout their soybeans for possible rust and be prepared to spray if you have not done so already," the commentary concluded.

Most Georgia soybean sentinel plots (MG-IV an MG-VI) are at the R7+ growth stage as of 9/7/06. Commercial soybeans in the state range from about R6 to R7 stages.

Reports of rust finds, increasing infections more frequent

Four new rust-positive counties -- Colquitt and Seminole in Georgia; Jackson in Mississippi and Florence in South Carolina -- have been reported in the last three days. Florence County is the farthest north and east rust is known to have traveled and caused visible infection this year.

Also today (9/7), Texas and South Carolina reported additional finds and increased disease severity in already positive counties.

Texas reported that on Sept. 6, "another commercial field with soybean rust was detected in Liberty County. This 150-acre field is at R5 and has a high incidence of rust in leaves within the lower and mid canopy."

The field is 5 miles to the north of the commercial field where rust was detected in August. This field is about 8 miles to the northwest of the diseased kudzu in Liberty County. No rust was seen in nearby soybeans or in kudzu to the north. There was scattered rain and cooler temperatures earlier this week in the area, the report said.

For South Carolina, the Sept. 7 commentary announcing the Florence County rust also said, "Disease severity continues to increase at the Calhoun and Orangeburg County sites."

SOURCE: Article by editor Marilyn Cummins, based on Georgia, Texas and South Carolina commentaries on and on archives.