'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 EFFECTIVENESS OF RESISTANCE TOWARDS SEPTORIA TRITICI BLOTCH (MYCOSPHAERELLA GRAMINICOLA) L. ERIKSEN, L. MUNK, H. +ANg-STERG+AMU-RD Plant Research Department, Ris+APg- National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark

The disease septoria tritici blotch, caused by the fungus Mycosphaerella graminicola, is among the most important diseases on wheat. The objective of this study was to describe changes in effectiveness of resistance to this disease over several years. To allow comparison of disease data collected on different locations over years, a linear regression of disease scores of individual cultivars on average disease scores of susceptible standards was performed. The coefficient of regression was used as a measure of the effectiveness of resistance. Field assessments from the Danish Observation Plots were analysed for the period 1996-2000. Among widely grown cultivars, ranging from susceptible to moderately resistant, no significant decrease in the effectiveness of resistance was observed.