AA ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases

In this report on the Ug99 strain of wheat stem rust:
[1] Scientists warn of new form of stem rust
[2] Dangerous wheat disease jumps Red Sea

[1] Scientists warn of new form of stem rust
Date: 16 Jan 2007
From: ProMED-mail <promed@promedmail.org>
Source: United Press International [edited]
<http://www.upi.com/NewsTrack/view.php?StoryID=20070116-103756-4197r>

US-based scientists say a new form of stem rust has moved from eastern Africa into Yemen and the Arabian Peninsula. Researchers with the Global Rust Initiative and the Agricultural Research Service of the United States Department of Agriculture say there's also evidence the disease has spread into Sudan, but more tests are needed to confirm the finding. Until the new findings, the strain of stem rust known as Ug99 had only been seen in Uganda, Kenya, and Ethiopia. The last major epidemic of stem rust occurred in North America during the early 1950s and destroyed as much as 40 per cent of the continent's spring wheat crop. Scientists plotting the probable trajectory of the new fungus say its spores can be carried over long distances by winds. Models predict that if the fungus crossed from eastern Africa to the Arabian Peninsula, it could easily spread to the vast wheat-growing areas of North Africa, the Middle East, Pakistan, and India.
According to the Food and Agriculture Organization of the United Nations, countries in the predicted, immediate pathway grow about 25 per cent of the Earth's wheat.

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

[2] Dangerous wheat disease jumps Red Sea
Date: 16 Jan 2007
From: ProMED-mail <promed@promedmail.org>
Source: Seedquest.com [edited]
<http://www.seedquest.com/News/releases/2007/january/18117.htm>

A new form of stem rust, a virulent wheat disease, has jumped from eastern Africa and is now infecting wheat in Yemen in the Arabian Peninsula.
Researchers with the Global Rust Initiative (GRI) and the Agricultural Research Service of the United States Department of Agriculture (USDA-ARS) have confirmed conclusively the existence of the disease in Yemen. There is also evidence that the disease has spread into Sudan, but more tests are needed to confirm the finding. Until this discovery, this new strain of stem rust, known as Ug99, had only been seen in Uganda, Kenya, and Ethiopia.

The last major epidemic of stem rust occurred in North America in the early 1950s, when a strain of stem rust destroyed as much as 40 per cent of the continent's spring wheat crop. Out of this crisis came a new form of international cooperation among wheat scientists worldwide, spearheaded by Nobel laureate wheat scientist Norman Borlaug. This international alliance of scientists led to the development of wheat varieties which resisted the onslaught of stem rust for more than 4 decades. But in 1999, a new strain of stem rust was discovered in Uganda and Kenya capable of destroying most previously disease-resistant wheat varieties.

A year and a half ago, geographic information systems specialists working at CIMMYT plotted the probable trajectory of the fungus, whose spores can travel large distances on the wind. The wind models predicted that if the fungus crossed from eastern Africa to the Arabian Peninsula, it could easily spread to the vast wheat-growing areas of North Africa, the Middle East, Pakistan, and India.

There is precedence for this, from a virulent strain of another wheat disease, called yellow rust, which emerged in eastern Africa in the late 1980s. Once it appeared in Yemen, it took just 4 years to reach wheat fields of South Asia. On its way, this new strain of yellow rust caused major wheat losses in Egypt, Syria, Turkey, Iran, Iraq, Afghanistan, and Pakistan, exceeding USD one billion in value.

There is every reason to believe the new Ug99 strain of stem rust represents a much greater risk to world wheat production. Annual losses of as much as USD 3 billion in Africa, the Middle East, and south Asia alone are possible. According to the Food and Agriculture Organization of the United Nations (FAO), countries in the predicted, immediate pathway grow more than 65 million hectares of wheat, accounting for 25 per cent of the global wheat harvest. "If we don't control this stem rust threat," says ME Tusneem, chairman of Pakistan's Agriculture Research Council, "it will have a major impact on food security, especially since global wheat stocks are at a historic low."

Experiments conducted over the past 2 years by international researchers in the Global Rust Initiative in Kenya and Ethiopia demonstrate clearly that most of the world's wheat varieties are susceptible to the new Ug99 strain of stem rust. "This is a problem that goes far beyond wheat production in developing countries," warns Borlaug. "The rust pathogen needs no passport to cross national boundaries. Sooner or later, Ug99 will be found throughout the world, including in North America, Europe, Australia, and South America."

GRI scientists have already identified promising experimental wheat materials with resistance to Ug99. But from the 1st breeding trials to growing new, rust-resistant varieties in farmers' fields on millions of hectares takes time and a massive effort. "If we fail to contain Ug99, it could bring calamity to tens of millions of farmers and hundreds of millions of consumers," says Nobel Laureate Borlaug. "We know what to do and how to do it. All we need are the financial resources, scientific cooperation and political will to contain this threat to world food security."

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

[The cereal crop plant wheat (bread wheat, _Triticum aestivum_ and durum wheat, _Triticum turgidum_) develops symptoms of stem rust when infected with the fungus _Puccinia graminis f.sp. tritici_. Severe losses due to wheat stem rust have been held at bay worldwide due to effective resistance breeding.

A strain of stem rust, now called Ug99, was found in Uganda in 1999, and it has since spread to Kenya and Ethiopia. It is thought to have the potential to seriously damage wheat production there and elsewhere. This is because it can overcome resistance in wheat offered by the commonly deployed Sr31 gene.

The 2 reports in this posting document the spread of Ug99 across the Red Sea to Yemen and possibly Sudan, and the consequences of that are spelled out in the 2nd report, which is well written and is included as a substitute for annotations I would have made here, so please read it carefully. The information was obtained from a press release from the Global Rust Initiative, and a link to their pdf file is in the 2nd item in "Links" below. This new outbreak of a major pathogen of a major food crop has to be seen as a very serious plant disease alert.

This posting provides an opportunity to point out that a reported find of Ug99 in 2006 in the coastal areas of Sindh, Pakistan (20060514.1366) was never confirmed to the best of my knowledge. The current report provides new information that would strengthen the prediction that reports from Pakistan may be possible in the future.

Map: <http://bbsnews.net/images/yemen_map.jpg>
Pictures:
Stem symptoms
<http://www.gov.mb.ca/agriculture/crops/diseases/images/fac15s01.jpg>
Ug99, Kenya
<http://www.cimmyt.org/english/wps/news/2005/sept/images/stem2.jpg>
Links:
<http://www.globalrust.org/>
<http://www.globalrust.org/images/IR2007_002_GRI.pdf>
<article in Farm Futures>

<http://www.cimmyt.org/english/wps/news/2005/sept/griMeeting.htm>
<http://www.apsnet.org/education/LessonsPlantPath/StemRustWheat/>.  - Mod.JAD]

[see also in the archive:
2006
---
Wheat stem rust, strain Ug99 - Pakistan: susp., 1st report 20060514.1366 Wheat stem rust, Ug99, new strain - East Africa 20050928.2849]