ABSTRACT
Scald (leaf blotch) is a common disease of barley (Hordeum vulgare; Fig. 1). It is caused by the fungal pathogen Rhynchosporium commune, which occurs worldwide due to its high genetic variability and climatic adaptability (Stefansson et al. 2013), but develops best in barley-growing regions with longer periods of cool, semi-humid weather. R. commune is a member of a fungal genus, of which five species with differing host specificities have been described to date (Caldwell 1937, Zaffarano et al. 2011; King et al. 2013). A previous review article (Shipton et al. 1974) mentioned yield losses of up to 40%, a number which, since then, has been cited frequently. However, the average yield losses in Europe and North America are rather closer to 5-10%, even if the frequency of symptom occurrence is higher. Nevertheless, regional losses as high as 65% can occur locally in epidemic years (Beigi et al. 2013). Furthermore, from areas where barley is continuously grown virtually without crop rotation such as in some parts of North Africa (Tunisia, Morocco, Eritrea and Ethiopia; Bouajila et al. 2006), South America (Peru, Colombia, Bolivia and Ecuador) and Central and Western Asia (Turkey, Syria and Iran; Bouajila et al. 2006; Arabi et al. 2008; Beigi et al. 2013), yield losses close to 100% have been reported (Abang et al. 2006).
