Cercospora Leaf Spot (CLS), caused by the hemibiotrophic fungus Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. During infection, C. beticola secretes effectors into the host to manipulate host physiology and establish disease. However, the effector repertoire of Cercospora beticola is mainly unexplored. This thesis aimed to identify and characterize novel C. beticola effectors as well as deepen our knowledge on previously-established C. beticola effectors. We found that the fungus utilizes proteinaceous and secondary metabolite effectors during infection. Interestingly, the fungus is equipped with specific effectors for host-necrosis induction in dark and light conditions. Moreover, the light-activated, non-host specific C. beticola toxin cercosporin that has previously been thought to be exclusively produced by Cercospora species was discovered to be also synthesized by other pathogenic fungi outside of the Cercospora genus.