June 15, 2006
From: ProMED-mail<promed@promedmail.org>
Source: stopsoybeanrust.com and sbrusa.net [edited]
<http://www.stopsoybeanrust.com/viewStory.asp?StoryID=852>


Florida officials have confirmed Asian soybean rust in 3 maturity groups of soybeans in a sentinel plot in Martin County. This is the first occurrence of soybean rust on soybeans planted this season anywhere in the U.S.

Carrie Harmon of the University of Florida told <www.StopSoybeanRust.com> there was a 29 percent incidence of rust in the plot, with the oldest infection being in the Group III soybeans.
She said it then spread to the Group V and then the Group VII in a pattern similar to that seen in plots in 2005.

The samples were collected by a scout yesterday in the sentinel plot near Jupiter, Florida, and, since this is the first time for rust in this southeastern Florida county, the spores were confirmed by PCR testing -- both conventional and real-time, Harmon said.

While she said this infection is not going to have a major impact on inoculum levels in the state, given how much lower those levels are compared to 2005 at this time -- this is the first positive rust find in the United States since rust was found on 2 Mar 2006, in Miller County, Georgia. That rust, on kudzu, was found to be growing again yesterday, also.

Harmon said she was not sure how much rain Tropical Storm Alberto dumped on Martin County, but she said there was an average of 3 inches of rain across the state during the storm. That still leaves a moisture deficit of 6 to 8 inches for the year, she said.

"The ground is saturated now, so we're having heavy fog and dew,"
she said. "That could lead to rust development, but it takes at least
7 days" for the resulting infection to be visible. Scouts are and will be out looking across the state.

The county, which is 3 counties north of Miami-Dade, where rust was found on kudzu on 13 Feb 2006, is now red on the USDA rust observation map, and an alert e-mail went out at 4:10 p.m. CDT. The official state commentary is not yet posted on the site.

Source: Interview with Carrie Harmon of the Southern Plant Diagnostic Network and the Department of Plant Pathology, University of Florida, Institute of Food and Agricultural Sciences; and <http://www.sbrusa.net.>

[Byline: Marilyn Cummins]

--
ProMED-mail
<promed@promedmail.org>

[Asian soybean rust(ASR) is a plant disease caused by the fungus _Phakopsora pachyrhizi_ and was introduced into the USA in 2004. In addition to the crop plant soybean (_Glycine max_), cowpeas, green beans, and other edible legumes can be affected by the ASR pathogen, which causes defoliation and yield reduction. Kudzu (_Pueraria lobata_, a.k.a. Japanese arrowroot) is an important alternate host for the pathogen in southern states of the USA.

This posting requires little comment, since it is the awaited first report of ASR on soybean in the USA 2006 crop season. Not too surprisingly, it is in Florida. The PCR testing noted in the previous post in this series was used to confirm the diagnosis. It is noted that wet storm-related weather is favorable for spread of ASR.

Only one "See also:" is given below, but please check it for broader context for 2006 and before.

Maps:
Asian soybean rust outbreaks 2006
<http://www.sbrusa.net>

The wheat rust corridor
<http://ars.usda.gov/images/docs/9757_9951/puccini_path.gif>

Pictures:
<http://www.dtnsoybeanrustcenter.com/index.cfm?show=65&mid=60&page=ALL>

Diagnosis cards (broadband best)
<http://www.aphis.usda.gov/lpa/issues/sbr/SBR_IDcard_11-04.pdf>

Links:
<http://www.sbrusa.net>

National commentary, updates from states, maps, chronology.
<http://www.stopsoybeanrust.com/mc_home.asp>

Latest news, articles, maps and tracking information.
<http://www.dtnsoybeanrustcenter.com/index.cfm?show=10&mid=31>

Latest news, articles and other information.
<http://www.stopsoybeanrust.com/mc_resources.asp>
- Mod JAD]

[see also in the archive:
Soybean rust, Asian strain update 2006 (05): USA 20060612.1642]