Physiological Specialization of a Local Population of Pyrenophora teres f. sp. teres

Abstract

Net blotch of barley, induced by Pyrenophora teres f.sp. teres, has showed an important increase in the past years, due to the adoption of zero tillage practices without an adequate crop rotation and the use of cultivars with intermediate levels of genetic resistance. Integrated management of this disease should include the diversified use of cultivars with effective resistance. Knowledge of pathogen population structure allows obtaining effective cultivars with genetic resistance to that population. In this study forty three isolates were inoculated in twenty barley genotypes under controlled temperature and photoperiod conditions. Eighteen isolates induced maximum virulence levels on all barley genotypes. It was not found a single isolate completely avirulent and all barley genotypes were susceptible to these isolates, in varying degrees. The cultivar INIA Ceibo exhibited the best relative performance, whereas the most susceptible were Ackerman Madi and Danuta. It was not possible to identify different virulence group profiles nor barley genotypes with differential resistance. The high variability found in these P. teres f. sp. teres and barley samples, are indicative that more comprehensive studies will improve the knowledge on virulence profile composition and on the genetic resistance and therefore will contribute to obtain barley cultivars with more effective resistance.