Abstract only

In west Asia, Central Asia and the Caucasus (CAC), and North African (CWANA) countries, wheat stands out for high value of production under irrigation, in higher rainfall and moderate rainfall agro-ecological areas. Monoculture of high yielding varieties is rapidly replacing the traditional lower yielding landrace cultivars. In CWANA countries, wheat yellow rust (Puccinia graminis fsp tritici) is among the diseases that present a clear danger to wheat production under irrigation and in the high rainfall areas. Annual yield losses have been recorded in one or more countries and in certain areas have reached epidemic levels. Yield losses of 20 to 80% have been recorded almost annually. Application of fungicides has become a common practice in many countries. Since 1970?s yellow has become sporadic due the exploitation of effective resistance genes in different forms and combination. Durable resistance has been linked to a number of genes such Yr18 and some very effective major effective genes such as Yr 9, Yr27; Yr1 that were associated with good parental lines and hence were extensively used by breeding programs globally. As Borlaug said: ?rust does not sleep? early 1980?s Virulent race affecting the Yr9 resistance gene occurred in East Africa and spread eastward through. Resistance genes Yr27, Yr18, and other Yr-Genes have effectively reduced the impact of yellow rust for over a decade. Recent virulence on Yr27 has been detected in rust trap nurseries. The spread of this new virulence is a typical example of potential risk of wheat rusts. The potential of wheat rust epidemics from new emerging virulent rust races remains a real threat to most wheat producing countries in the world.

Global Wheat Program

English

INT3065|INT3301|INT0610

CIMMYT Staff Publications Collection