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Fungal resistant varieties boost wheat yields in Kenyas
November 10, 2013, 11:30 am

New richer yielding wheat varieties developed by scientists to resist the stem-rust disease, which has been devastating wheat crops in region for much of last decade, are proving a blessing for wheat farmers across Africa.

Known as Ug99, the fungal stem-rust disease thrives in warmer temperatures, and the spores can travel thousands of kilometers aided by wind, according to Peter Njau, a research scientist at the Kenya Agricultural Research Institute (KARI).

As the name suggests, Ug99 was discovered in Uganda in the year 1999. It has since spread through Kenya to Ethiopia, Sudan and Egypt, and across the Red Sea to Yemen and Iran, causing havoc for farmers along the way. There are fears the disease could reach India and other major wheat-producing countries in Asia.

Stem rust has been around in different forms since Roman times, and in the early part of the 20th century, it repeatedly destroyed more than 20 percent of the U.S. wheat harvest. However, by the 1970s, it was apparently extinct. But over the decades, the fungus that causes stem rust evolved and resulted in Ug99, a strain that has the potential to destroy 80 percent of the world's wheat production.

Wheat is an important cereal in Africa, and demand is growing faster than for any other food crop. According to the International Maize and Wheat Improvement Center (CIMMYT), the continent produces between 20 million and 25 million tonnes of wheat annually. But in 2010 - the latest year for which data is available - African countries imported around 38 million tonnes of wheat to help meet demand.

Scientists say Ug99 is the most virulent pathogen in the history of stem rust. When it attacks, the fungus absorbs nutrients that would otherwise be used for grain development. The disease also interferes with the plant's vascular tissue, leading to shriveled grains, said Sridhar Bhavani, a CIMMYT wheat pathologist and breeder who coordinates nurseries set up to screen stem rust in East Africa. The disease has the capacity to turn a healthy-looking crop, only weeks from harvest, into nothing. Losses due to the fungus have been recorded at between 70 and 100 percent.

Since 2006, CIMMYT scientists, with technical support from KARI, have been testing and crossbreeding thousands of wheat varieties sourced from all over the world to identify particular varieties that are resistant to Ug99. The research is funded by the Bill and Melinda Gates Foundation, Britain's Department for International Development (DFID) and USAID.

Bhavani said the CIMMYT-KARI collaboration has led to the development of eight wheat varieties that are resistant to the stem-rust disease and are also very high-yielding. So far, two of the Ug99-resistant wheat varieties — ‘Robin’ and ‘Eagle10’ — have been released and have become popular with the farmers.

The remaining six are still undergoing seed multiplication before being made available to farmers.

"I have never seen such a high-yielding variety since I started wheat farming 20 years ago," said Oliver Nightingale, a large-scale farmer from a family that has been growing wheat and barley in Kenya for the past 107 years under the name Sasumua Agriculture Ltd. In response, the Kenyan government is growing the new varieties for seed multiplication on 53 acres of land under a program backed by the World Bank. In addition, KARI expects to harvest 600 metric tonnes of seed to be supplied to farmers come next season.

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