Wheat rusts: Renewed push by FAO and partners to combat crop disease

Activity by the Food and Agriculture Organization of the United Nation (FAO) and partner groups is being ramped up to combat the threat of wheat rusts.

A fungal plant disease, wheat rust can turn “a healthy looking crop, only weeks away from harvest, into nothing more than a tangle of yellow leaves or black stems and shriveled grain”, said the FAO.

The disease can travel by wind and be highly mobile, with yellow and stem rusts spreading widely in recent years.

"Under conducive conditions, up to 80% of a farmer's yield can be lost due to rust infections, so building countries' capacity to detect them and better understand the ways the various strains of the disease spread is crucial to preventing epidemics and limiting losses," said FAO plant protection officer Fazil Dusunceli.

Ug99 detected in Egypt

One highly potent stem rust is Ug99, which has the potential to affect the majority of wheat varieties grown worldwide. It was first detected in Uganda in 1999 and has since spread to 13 countries, most recently being detected in Egypt, one of the Middle East's key wheat producers.

The FAO is also concerned about a new strain of yellow rust, called Warrior, that has traveled from northern Europe to Turkey.

In order to help study, detect and prevent the threat of wheat rusts, the FAO is expanding its partnership with the International Center for Agricultural Research in the Dry Areas (ICARDA) and the University of Aarhus' Global Rust Reference Centre to provide training on surveillance, resistance and management. Country surveys and sample analysis are also planned to better understand and manage the spread of the diseases.

Success of vigilance and early action

The FAO said the value of surveillance programs had been in highlighted in Egypt, where vigilance and early action had prevented the spread of Ug99.

ICARDA, the FAO and Turkey's General Directorate of Agricultural Research (GDAR) are collaborating with the International Maize and Wheat Improvement Center (CIMMYT), the University of Aarhus and the Borlaug Global Rust Initiative (BGRI) to train plant protection officers at a 10-day workshop in Izmir, Turkey. Twenty-two officers from Central Asian and Near East countries with known cases of wheat rusts will be trained on rust surveillance, resistance and management during the workshop.

In addition to Central Asia and the Middle East, FAO is also engaging with countries in Eastern Africa as new strains of stem rust have been detected in Ethiopia and Kenya.

New type of yellow rust found in UK

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UK crop scientists and breeders have been told high yellow rust levels were further evidence of the diversification of the UK pathogen.

A unique yellow rust pathotype not observed before in the UK had been identified in samples taken from sites with unexpected levels of yellow rust in Essex, North Yorkshire and Scotland in 2015, the UK Cereal Pathogen Virulence Survey (UKCPVS) told delegates at a UK event last month.

It’s too early to tell if this new pathotype caused the high yellow rust levels but our adult plant tests this summer will help provide an answer,” said UKCPVS project manager Dr Sarah Holdgate.

Warrior-type rusts had accounted for 70% of samples tested, she added.

When it was detected in 2011, Warrior 1 was dominant. Since 2012, the Warrior 4 group has increased in frequency.”

Lower brown rust levels

Although lower levels of brown rust were reported in 2015, UKCPVS reported that the wheat brown rust population has changed over the past few years with tests showing isolates are becoming more complex.

The ability of populations to change rapidly does mean the season can throw up surprises,” said Dr Jenna Watts, research manager at the AHDB. “As a result, it is really important to monitor all crops for disease and alert UKCPVS to any unexpected observations.”

Delegates were told yellow and brown rust had been active in crops during the autumn and winter, creating the potential for a “significant epidemic” development this spring.