Virulence Spectrum to Barley in Some Isolates of Pyrenophora teres from the Mediterranean Region. Moncef Harrabi, Professor, INAT, 43 Ave. Charles Nicolle, 1002 Tunis, Tunisia. Ahmed Kamel, International Center for Agricultural Research in the Dry Areas (ICARDA), Tunis Office, BP84, 2049 Ariana, Tunisia. Plant Dis. 74:230-232. Accepted for publication 18 August 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0230.

Thirty-three isolates of Pyrenophora teres, the causal agent of net blotch of barley (Hordeum vulgare), were collected from Tunisia, Algeria, Morocco, Egypt, and Cyprus. Their virulence spectra were determined using 10 differential barley cultivars. A cluster analysis indicated that the isolates belonged to four groups. The North African isolates had a higher mean virulence and a low variance across all cultivars; these isolates can be considered as complex races. All isolates were virulent on cultivar Martin, which is widely grown in Tunisia. None of the cultivars tested were highly resistant to all isolates investigated.