ASSESSMENT OF CULTIVAR PERFORMANCE AND DISEASE IMPACT ON CEREALS IN MOROCCO

Lines and cultivars of barley, bread, and durum wheats were seeded at nine sites in 1984 and 12 sites in 1985 and 1986 in all cereal-growing regions of Morocco to build a data base on regional performance and disease effects. Disease assessments were made four times annually at each site at the same growth stage. Area under the disease progress curve (AUDPC) values were calculated for foliar and root diseases, viruses, and barley stripe. Barley and bread wheat yield losses were most severe along the Atlantic coast (Rharb and Sidi Allal Tazi). All barley and all bread wheat cultivars except Tegey 32 had severe disease loss in at least one location. No yield loss occurred with durums. There were significant cultivar effects for AUDPC by severity among barleys and bread wheats but not among durums. Some barley lines had good resistance to net blotch, the most prevalent disease, but were susceptible to spot blotch. Conversely, all barley cultivars were susceptible to net blotch, but Rabat 071 and895 were resistant to spot blotch development. Bread wheat line 1723 and cvs. Jouda, Tegey 32, and Merchouch 8 had lower total AUDPC values (by severity) than the popular cvs. Nesma and Siete Cerros. Generally, breeding lines were more resistant than cultivars to leaf rust, but all were equally susceptible to Septoria leaf blotch. AUDPC values for durum wheats were consistently lower than values for bread wheats to all diseases except bacterial leaf streak, which was observed only on durums. Disease was much less at Merchouch, the principal site for cultivar selection, than at Rharb and Sidi Allal Tazi. Selection for resistance to wheat leaf rust and to Septoria leaf blotch could be made at Tangier and Sidi Allal Tazi, respectively, without severe interference from other foliar diseases.