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ALERT: Rust found in Sunbelt Expo plot in Colquitt County, GA
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7/26/2005 -- 11:10 p.m. CDT; updated 7/27 9 a.m. -- Asian soybean rust was confirmed today on two leaves out of a 100-leaf sample at the Georgia sentinel plots at the Sunbelt Expo in Colquitt County, Ga. The county is directly southwest of Tift County, where rust was found in a sentinel plot on July 18.
Bob Kemerait. assistant professor and Extension specialist, University of Georgia, turned the county red on USDA rust site at about 10:40 p.m. on 77/26. The Sunbelt Agricultural Exposition is held at Moultrie, Ga., which is the Colquitt county seat in the center of the county. This year's Sunbelt Expo, an annual event, is set for October 18-20, 2005.
This find brings the 2005 infected Georgia county count to four: Colquitt, Decatur, Seminole and Tift. (See census map for all Georgia counties.) There are now 14 U.S. counties overall found to have rust this year -- either on soybeans, volunteer soybeans or on kudzu.
Update with more details from Kemerait on 7/27
In an e-mail to the IPM soy rust listserv of his colleagues across the country, Kemerait these details, which go beyond the state commentary on the Web (reported later in this story):
Several pustules, each with profuse sporulation, were found on the two positive leaves of the 100 collected by Layla Sconyers
Kemerait traveled with Glen Hartman across the SW portion of GA on Tuesday, stopping along the way to scout commercial soybean fields and/or kudzu patches in a number of counties. We did find additional kudzu leaves in the known infected patch in Decatur County just north of Quincy, FL, that
contained pustules and abundant sporulation.
Kemerait said in another e-mail that "It is evident that the high
temperatures in south Georgia lately have not eliminated profuse sporulation
at this site (of kudzu in Decatur County."
HOWEVER, although careful observations with
a dissecting microscope are not complete, we have not found further
evidence of rust in Worth, Lee, Terrell, Calhoun, Early, Seminole, or
Mitchell counties in GA. At the very least, spread of rust seems to be slow in
the Coastal Plain of Georgia at this point.
Georgia state commentary for July 26, 2005
Here is Kemerait's full report from the USDA site, which also recaps prior finds and the USDA mobile team update:
Observations: Georgia state report from 26 July 2005: Soybean rust was confirmed on two leaves from 100 leaves collected at the Georgia Sentinel Plots at the Sunbelt Expo (Sunbelt Agricultural Exposition) in Colquitt County. Colquitt County is directly southwest of Tift County.
Also on 26 July, the USDA mobile team made a broad sweep through Worth, Lee, Terrell, Calhoun, Early, Seminole, Decatur and Mitchell Counties scouting commercial soybean fields and also kudzu patches for rust. While we did find additional rust in the previously reported kudzu patch in Decatur County, additional rust sites were not found. The samples will continue to be evaluated over the next two days.
As of 26 July, it seems that soybean rust is still quite limited in Georgia and, where it does occur, is very limited in abundance.
Report from 22 July 2005: Asiatic soybean rust was confirmed morphologically today from a soybean leaf collected on 21 July in the sentinel plots at the Attapulgus Research Station in Decatur County. This sentinel plot is approximately 2 miles north of the kudzu patch where rust was found on 21 July. Rust pustules and copious spores were found on only one leaf from the sample of 100 collected.
Report from 21 July 2005: Soybean rust was confirmed this afternoon on kudzu growing in extreme southern Decatur County, near the Florida border. The patch of kudzu was first scouted last week and no rust was found. The patch, approximately 2 miles south of the Georgia sentinel plot in Attapulgus, was scouted again today and numerous pustules and copious spores were found on one leaf.
Report from 20 July 2005: In the past 10 days, the disease diagnostic clinic in Tifton has received numerous soybean samples and additional kudzu samples to examine for soybean rust. At this time, no additional rust has been found beyond that reported from the Lang Farm, Tift County, on 18 July. Downy mildew is fairly common across the Coastal Plain of Georgia.
Report from 18 July 2005: Dr. Layla Sconyers, research associate in the Department of Plant Pathology today found approximately a half-dozen pustules of soybean rust on a single leaf (from a sample of 100 collected on 15 July). The diagnosis was confirmed morphologically by diagnostician Jason Brock and Dr. Bob Kemerait based upon presence of pustules and characteristic spores. The sample was collected at the Lang Research Farm on the Coastal Plain Experiment Station in Tifton, GA, in one of our sentinel plots.
Growth Stages: Growth stage of most mature soybeans in the Colquitt County sentinel plots on 25 July are R4-R5. Growth stage of sentinel plots in Attapulgus on 21 July from which leaf sample collected: R4-R5. Growth stage of sentinel plots in Tifton where rust was confirmed as of 18 July: R5.
Management: Based on the USDA Mobile Team travel on 26 July, soybean growers in southwest Georgia should feel confident that soybean rust is still quite limited in distribution in the state.
As of 21 July: The finding of rust on kudzu in Decatur County further strengthens our belief that rust has spread to some degree in the state. Growers in the Coastal Plain are advised to begin a fungicide program as the crop enters reproductive growth, and reassess the spread of disease before making additional applications.
As of 20 July: Growers in the Coastal Plain of Georgia whose crop is at or beyond first bloom are encouraged to consider application of some fungicide to protect the crop. They should then reassess the situation in 2-3 weeks to find any further treatment is warranted. Growers may be able to tank-mix a fungicide with another product (e.g. boron or dimilin) and save a trip across the field.
As of 18 July: With the discovery by Dr. Sconyers of initial infection by soybean rust in sentinel plots in Tifton, GA, growers in the Coastal Plain will be advised to initiate fungicide programs as their crop reaches first bloom. Growers who are beyond this stage will be advised to make fungicide applications.
Forecast Outlook: Typical summer thunderstorms have continued over much of Georgia. Conditions seem quite favorable for spread of soybean rust, though high temperatures may slow the spread somewhat?
Scouting Recommendations and Techniques: Scouting of fields should intensify immediately. With rust found in Florida, Alabama and Georgia, it seems very likely that the disease will spread.
We advise growers, consultants and scouts to carefully examine multiple leaves from the upper, middle, and lower parts of the canopy in commercial fields to watch for appearance of rust. NOTE: Soybean rust pustules are much smaller than other rusts with which you may have greater experience, such as corn rust and common bean rust. Detection in earliest stages will take careful observations.
Source: Georgia state report from July 26 on www.sbrusa.net, supplemented with Sunbelt Expo and Colquitt County information on the Web and an additional e-mail circulated by Bob Kemerait of UGA.
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