Chapter 28 - Septoria nodorum – a possible yield-limiting factor of barley in Ireland?

Abstract

Septoria nodorum is a limiting factor to yield in wheat in Ireland, but has recently appeared on barley. Cross-infections could be responsible for interchange of inoculum. To test this hypothesis wheat and barley single-spore isolates were passaged through their opposite hosts. Disease assessment and yield data showed that the passaged wheat isolate remained largely unaltered; however, the barley isolate responded after the third wheat passage by causing significantly less disease and significantly higher yields in barley than the unpassaged isolate with the converse occurring on wheat after the second wheat passage. Data obtained are discussed in the context of cultural observations made on colony morphology during host passage sequences and possible genetic mechanisms responsible.