RESUMEN
Net blotch, caused by the phytopathogen Drechslera teres, is a common disease of barley (Hordeum vulgare L) and is responsible for large economic losses in some barley growing areas. In this study the morphology and genetic variability of eight D. teres isolates from different regions of the Brazilian state of Rio Grande do Sul were investigated. Colony morphology was studied on potato-dextrose-agar (PDA) and genetic variability investigated using the random amplified polymorphic-DNA (RAPD) technique. 27 commercially available primers were tested of which 16 were selected for use in polymorphic analysis due to their good resolution and reproducibility. Similarity coefficients were used to construct dendrograms based on colony morphology and RAPD data showing the relationship between the eight isolates studied. Colony morphology showed variability between the isolates while RAPD assays showed high similarity coefficients, but grouping of the isolates according to the geographic origins of the seeds from which they were isolated was not possible