Pyrenophora teres is a fungal pathogen of barley and other closely related grass species. Two forms of the pathogen, P. teres f. teres and P. teres f. maculata, are the causative agents of net form net blotch and spot form net blotch of barley, respectively. Genetic and bioinformatic approaches were used to identify eight candidate effectors in the P. teres f. teres PttBee1 region. Genes were validated using CRISPR-Cas9 mediated gene disruptions. As no transformants displayed alterations in virulence, additional markers were implemented into a P. teres f. teres genetic map to refine the locus. As P. teres f. maculata has recently emerged as a pathogen of wheat, a quantitative trait loci analysis and genome wide association study were performed with this pathogen using a durum wheat biparental mapping population and a subset of the Global Durum Wheat Panel, respectively, both showing an association with resistance/susceptibility on chromosome 2A.