Relative virulence of 15 Stagonospora (Septoria) nodorum (SNB) monopycnidiospore isolates and their mixture was studied under field conditions on a differential set of triticale and bread wheat cultivars. The isolates originated from diseased triticale and wheat plants sampled in diverse geographical regions of Poland. Significant effects of isolates, cultivars, and cultivar by isolate interactions were detected. The interaction between S. nodorum isolates and wheat and triticale genotypes appeared to be to a great extent a statistical interaction, rather than a well defined physiological specialization. The detection of the interaction was influenced by the amount of disease inflicted by the pathogen isolates on selected host genotypes and the effect of environmental conditions on disease development, as well as by the tools and precision with which the host was examined. Nonetheless, since the isolate by cultivar interaction was significant in most cases, the term virulence is used. The mixture of isolates was classified among isolates showing intermediate virulence on the cultivars tested. In comparison to single isolates, the differential capacity of the isolate mixture was also reduced. Relationships between mean isolate virulences and cultivar variances of SNB reactions were not significant for leaves (moderate SNB level) and significant for heads (low SNB level). A single pathogenic isolate used for screening breeding materials may provide reliable information on their SNB resistance.

English

9910|AGRIS 0001

Jose Juan Caballero

CIMMYT Publications Collection