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[1] Soybean rust update and outlook - USA
[2] Detecting soybean rust by satellite - South Africa, USA
[3] Federal probe of soybean rust report - USA (IA)
 

[1] Soybean rust update and outlook - USA
Date: Mon 11 June 2007
Source: Iowa State University Integrated Crop Management via StopSoybeanRust.com [edited] <http://www.stopsoybeanrust.com/viewStory.asp?StoryID=1051>

For the past 2 years, we used a computer model to predict the risk of seasonal outbreaks for soybean rust during a growing season. This year [2007], we improved the model and are making predictions using this model together with information from sentinel plot data. Below is an update of the occurrence of soybean rust and our seasonal outlook.

Situation in the southeastern region

The source regions of soybean rust this year [2007], are in 3 areas along the Gulf Coast: Texas, Louisiana, and the southeastern region, including Florida and Georgia. For the eastern region, which has the largest source area, the weather in Florida has been dry for the entire month of May [2007], and that greatly slowed soybean rust development. Spore movement has been limited to areas east of the Appalachian Mountains.

In Louisiana, soybean rust was found in an area west of New Orleans.
Detection was 51 days earlier than in the previous 2 years. However, computer modeling indicates little spore movement northward from that source. No disease has been found anywhere north of New Orleans, although local expansion has been observed. For the rest of June [2007], computer models predict limited northward movement of this disease from known Louisiana sources because the predicted weather seems less favorable to the disease.

In Texas, a new occurrence of the disease was found along the Gulf of Mexico north of Houston. No disease was found in areas where the disease was 1st detected in winter. There were abundant rains in Texas in the past few weeks, which were favorable to the occurrence of soybean rust. However, predicted favorability for soybean rust occurrence for Texas in June [2007] is less than 20 percent.

Like last year [2006], a system to monitor spores has been established in the soybean production region by university scientists with support from Syngenta. So far, the northernmost detection of soybean rust spores was in South Carolina during the last week of May. No disease has been found yet. The detection in South Carolina was consistent with predicted spore movement. However, that finding does not pose a significant threat to the North Central Region because the disease normally does not move westward over the Appalachian Mountains.

Future outlook

To determine the risk of soybean rust in the North Central Region, what happens in the Gulf Coast states before the end of June [2007] is critical.

Getting into July [2007], the weather will be too hot for soybean rust to develop. For the period of May through the 1st week of June [2007], there has been abundant rainfall in the Mississippi Basin and the Great Plains Region, including Texas. Such weather is ideal for soybean rust development, if spores and hosts are available. Luckily, soybean plants were just planted. Arrival of spores was not predicted by computer models. The possibility of having the disease occur in areas beyond northern Louisiana into Arkansas and Kentucky and go undetected is not high.

Our computer forecast shows that the month of June is less favorable to the establishment of soybean rust in the entire soybean production area because of less rain. The predicted spore movement from known sources of soybean rust is also limited in the eastern region. We are using a newly reported area in Texas for our next forecast. Since the critical stage in the Gulf Coast Region is not over yet, we will continue to watch what happens there. Disease occurrence in mid-Mississippi is what we need to watch before the end of June [2007].

Besides computer modeling and spore monitoring, we have another safeguard system, sentinel plots, to protect us from any surprises.
In Iowa, all the sentinel plots have been planted.

[Byline: XB Yang, Iowa State University, Zaitao Pan, St. Louis University]

--
Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator <dodds@ucr.edu>

[2] Detecting soybean rust by satellite - South Africa, USA
Date: Thu 14 June 2007
Source: Wisconsin Ag Connection [edited]
<http://www.wisconsinagconnection.com/story-national.php?Id=1378&yr=2007>

Iowa State University (ISU) researchers have developed a way to use satellite images to find Asian soybean rust. "What we did on the ground 10 to 15 years ago, we can do now with satellites," said Forrest Nutter, professor of plant pathology.

Using remote sensing, Global Positioning System (GPS), and Geographical Information System technologies, scientists can measure the green leaf area of soybeans to detect and identify diseases down to the area of a square meter, about 1.2 square yards. "Plant pathogens and pests impact the green leaf area index of crop canopies in different ways and those changes can be detected and quantified using remote sensing," Nutter said. The footprints of early soybean rust infection are oval-shaped. The way it spreads over time in a field helps identify it from other diseases.

Nutter envisions the technology being used to narrow the search for soybean rust or other diseases. Plant disease detection using satellites would provide the GPS coordinates for spotters on the ground to pinpoint locations to collect disease diagnostic field samples. The samples would then be taken in for laboratory tests to confirm the identity of the plant disease at that location.

Tests conducted last year [2006] in South Africa demonstrated the technology. Nutter has been working on the project with plant pathologist Neil van Rij of Cedara, South Africa; John Basart, Iowa State engineering professor; and Khalil Ahmad, engineering graduate student. Nutter said the USDA (US Department of Agriculture) and the Department of Homeland Security are interested in using the technology to alert officials to a soybean rust infection during the crop season. Being able to monitor the movement of soybean rust could help reduce the impact of the devastating disease.

--
Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator <dodds@ucr.edu>

[3] Federal probe of soybean rust report - USA (IA)
Date: Tue 29 May 2007
Source: Agri News [edited]
<http://webstar.postbulletin.com/agrinews/293805652974493.bsp>


Federal investigators are looking into how and why a single leaf infected with Asian soybean rust was found in Iowa in March [2007].
Officials with the Iowa Department of Agriculture (IDA) and Land Stewardship and Iowa State University (ISU) haven't found additional evidence of the Asian rust in the field where the leaf was reported to have come from or in neighboring fields. "We did verify that one leaf submitted in a plant sample was infected with Asian soybean rust, but how it got into Iowa still needs to be determined," said Bill Northey, Iowa Secretary of Agriculture. "After careful examination of the materials collected to date, we believe no Asian soybean rust infection occurred during the 2006 growing season in Iowa."

Iowa officials determined the situation warranted additional investigation by the USDA's (US Department of Agriculture) Office of Inspector General. Paul Feeney, with the Office of Inspector General, had no comment on whether there was or wasn't an ongoing investigation.

On March 8 [2007], a sample was submitted to ISU's Plant Disease Clinic. The sample was made up of soybean seeds and pieces of pods, stems, and a leaf. The sample was reportedly taken from a bin of soybeans harvested in Mahaska County in 2006. ISU's testing revealed Asian soybean rust. On March 12 [2007], the USDA lab in Beltsville, Maryland, confirmed that the single leaf in the sample was infected.

IDA and ISU personnel then collected additional samples from bins at the location where the sample was allegedly collected. They found no symptoms or signs of rust, said Greg Tylka, ISU plant pathologist.
Next they extensively collected leaves from the field where the sample reportedly was harvested and from adjacent fields. Tylka said a sentinel plot 15 miles (about 24 km) from the farm showed no evidence of rust. An extensive statewide plant disease survey also came up empty. "Other than that one leaf, we saw nothing," Tylka said.

The Iowa Soybean Rust Team pointed out in March [2007], that rust didn't pose a risk for the 2007 growing season. The fungus and spores that cause the disease can't survive an Iowa winter, said Tylka. As in previous years, producers need to continue to be vigilant and monitor conditions that favor rust, Tylka said.

[Byline: Jean Caspers-Simmet]

--
Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator <dodds@ucr.edu>

[Asian soybean rust, caused by the fungus _Phakopsora pachyrhizi_, is a major soybean disease 1st detected in Japan in 1902. It can cause premature defoliation, with yield losses of up to 70 percent reported in farms in Asia. The disease was discovered for the 1st time in the continental USA in 2004. It has for some years been active in Asia and Australia, causing periodic epidemic outbreaks in some regions, and has in recent years spread to Hawaii and Puerto Rico. Data are lacking concerning its establishment in Europe but it has been placed on the European [and Mediterranean] Plant Protection Organization (EPPO) alert list. New strains with increased virulence are emerging. Kudzu (_Pueraria lobata_), an introduced weed species, can serve as a pathogen reservoir. _P. meibomiae_ is a less-virulent related species found in South America where it also causes soybean rust.

Maps
US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>
Current distribution of soybean rust in the US:
<http://www.sbrusa.net/>
Worldwide distribution up until December 2005:
<http://www.eppo.org/QUARANTINE/Alert_List/fungi/maps/PHAKPA_map.htm>
Pictures of soybean rust symptoms
<http://soybeanrust.unl.edu/soybean/siteImages/plantdate.gif> and <http://soyrust.cropsci.uiuc.edu/images/blight1.jpg>
Links
Information on soybean rust:
<http://www.aphis.usda.gov/plant_health/plant_pest_info/soybean_rust/background.shtml>
Diagnostic fact sheet:
<http://nt.ars-grin.gov/taxadescriptions/factsheets/index.cfm?thisapp=Phakopsorapachyrhizi>
_P. pachyrhizi_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=121037>
_P. meibomiae_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=102469>
Rust background, tracking, and current information:
<http://www.stopsoybeanrust.com/> and
<http://www.sbrusa.net/>
EPPO alert list:
<http://www.eppo.org/QUARANTINE/Alert_List/fungi/PHAKPA.htm>. - Mod.DHA]

[see also in the archive:
Asian soybean rust, kudzu - US (LA) 20070517.1567 Asian soybean rust, plant tissue - USA (IA) 20070410.1214 Soybean rust, Asian strain, update 2007 - USA 20070318.0952 Soybean rust, Asian strain, update 2006 - USA 20070317.0942
2006
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Soybean rust, Asian strain, soybean - USA (KY): 1st report 20061017.2985 Soybean rust, Asian strain - USA (IL): 1st report 20061014.2948
2005
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Soybean rust, Asian strain - USA: 2005 disease summary 20051228.3694 Soybean rust, Asian strain, kudzu control 20051006.2914
2004
----
Soybean rust - USA: 1st report 20041110.3043]

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