February 6, 2017

Stem rust could evolve to "largest outbreak" to hit Europe's wheat, scientist warns

Wheat in Europe - the world's biggest producer of the crop - lies in the threat of a newly discovered and devastating strain of fungus, weekly science journal Nature reported.

The first infection involving the TTTTF stem rust fungus happened in Sicily in 2016, and is prognosticated to become the "largest outbreak" in the region in many years, according to Chris Gilligan, an epidemiologist at the University of Cambridge, UK, who leads a team that modelled the probable spread of the fungus's spores.

The fungus is so named for the characteristic brownish stain it creates as it destroys wheat leaves and stems. In Sicily, TTTTF has adversely affected tens of thousands hectares of crops, and could infect dozens of laboratory-grown strains of wheat, including varieties with strong tolerance against diseases, researchers said. 

In addition, the Global Rust Reference Center (GRRC) and the International Maize and Wheat Improvement Center (CIMMYT) reveal two new strains of the wheat disease, yellow rust, which for the first time have been seen over large areas in Europe, North Africa, East Africa and Central Asia. While the impact of yellow rust remains unknown, the pathogens appear to be intimately connected to virulent strains previously reported in North America and Afghanistan. 

In the meantime, the Food and Agriculture Organization of the United Nations (FAO) has issued alerts about the three diseases on February 3. It is hoped that the early warnings could prepare farmers to apply protective measures such as field monitoring, the use of fungicide and production of resistant variety plants.

In the 1990s and 2000s, the stem rust type, Ug99, hit Africa and parts of the Middle East, sparking off international panic as more than 90% of wheat crops were vulnerable to the pathogen. Europe, along with China and North America, managed to remain unaffected by the disease, and had not seen stem rust epidemics since the 1950s, Mogens Hovmøller, the leader of a GRRC testing team, said.

Gilligan's team at Cambridge University together with CIMMYT and the UK's Met Office in Exeter, found that stem-rust spores released during the Sicilian outbreak could have been deposited throughout the Mediterranean region. Although the development does not confirms the spread of the infection since spores may not have survived the winter, its seriousness warranted a timely warning from the scientific community.

- Nature