Investigations of changes in varietal resistance to Septoria tritici as a factor contributing to the increased national importance of this disease

Abstract

The aim of this investigation was to establish whether the increased importance of Septoria tritici as a disease of winter wheat during the 1980's was related to declining varietal resistance. Thirty two varieties, which had been widely grown between 1970 and 1989, were tested for resistance to S.tritici by inoculation and by exposure to natural infection. Results indicate a marked decrease in the resistance of the national wheat acreage during the late 1970's and early 1980's compared with earlier years. It is probable that this shift in varietal resistance contributed to the upsurge of S.tritici during the 1980's.