Share|When stripe rust disease  strikes a susceptible wheat crop, the results are usually devastating. The fungus can spread like wildfire, quickly transformin…

Winning the Battle Against Deadly Wheat Fungus

Photo credit: Thomas Lumpkin, CIMMYT
Wheat leaf infected with stripe rust, also known as yellow rust (Puccinia striiformis)

When stripe rust disease  strikes a susceptible wheat crop, the results are usually devastating. The fungus can spread like wildfire, quickly transforming fields of healthy wheat into yellow swathes of stunted grain. The disease results in fewer spikes, fewer grains per spike, and shriveled grains with reduced weight.

“You see very beautiful fields actually, yellow like a canola field in flower,” says Firdissa Eticha, the national wheat research program coordinator with the Ethiopian Institute of Agricultural Research (EIAR). “But for farmers, it is a very sad sight. Stripe rust can cause up to 100% yield loss.”

And Eticha should know. Ethiopia’s wheat crops became of one the casualties in the race against the disease in 2010, when a severe stripe rust epidemic struck the country, hitting many dominant wheat varieties. This threat was further compounded by climate change, with persistent gentle rains throughout the year, and prolonged dews and cool temperatures – perfect weather for stripe rust. There was little Ethiopia could do to prevent the epidemic. Imported fungicides controlled the disease when they were applied on time, but supplies were limited and expensive.

But Ethiopia was not alone. Many countries in Africa, the Middle East, and Asia, struggled to control the epidemic in 2009 and 2010. But even more alarming was the evolution of new races of stripe rust that are able to overcome a major wheat gene (Yr27) that was previously resistant to the disease.

CIMMYT’s Global Wheat Program

Although recent weather conditions have allowed the new rust races to thrive, the fungus first began to emerge more than a decade ago. As a result, CIMMYT’s Global Wheat Program, which tries to anticipate the next stripe rust threat, began selection for resistance to Yr27-virulent races in 1998.

“CIMMYT has a number of wheat lines that have shown good-to-excellent resistance to stripe rust without relying on Yr27, in screening in Mexico, Ecuador, and Kenya,” says Ravi Singh, a CIMMYT scientist and rust expert who leads the breeding effort in Mexico.

Seed multiplication of resistant CIMMYT varieties

Currently, CIMMYT is working with national programs to identify and promote the best resistant materials for individual environments — a process that was underway in Ethiopia when the epidemic struck. Indeed, newly released wheat varieties derived from international partnerships have proven to be resistant to the disease, and are now being multiplied for seed. In particular, two CIMMYT lines released in Ethiopia in 2010 have shown to be both high yielding and resistant to stripe rust in their target environments.

EIAR and the Ethiopian Seed Enterprise, a government company specializing in providing select seed, worked together to speed the multiplication of seed of these varieties, with financial support from the USAID Famine Fund. Two resistant lines from the International Center for Agricultural Research in the Dry Areas (ICARDA) were released in Ethiopia in 2011, and will add to the diversity for resistance.

Nine hundred farmers grew the new varieties on small on-farm demonstration plots in 2010, resulting in disease-resistant crops. More demonstration plots will be made available as more seed becomes available.

The importance of partnership

“The contribution of CIMMYT is immense for us,” says Eticha. “CIMMYT provides us with a wide range of germplasm that is almost finished technology — one can say ready materials that can be evaluated and released as varieties that can be used by farming communities.”

Bekele Abeyo, a CIMMYT senior scientist who works closely with national programs in Ethiopia, also emphasized the importance of partnership. “I think East Africa is colonized by rust,” he says. “Unless national programs work hard to overcome and contain disease pressure, wheat production is under great threat. It is very important that we continue to strengthen the national programs to overcome the rust problem in the region.”

With Yr27-virulent stripe rust varieties now widespread throughout the world, Ethiopia’s story is reflected in many CIMMYT partner countries. The challenge is to work quickly together to identify and replace susceptible varieties with the new, productive, resistant materials.

Read the full story: Resistant wheats and Ethiopian farmers battle deadly fungus
Find out more about CIMMYT’s Global Wheat Program

Photo credit: Thomas Lumpkin, CIMMYT

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