Cercospora beticola is a hemibiotrophic fungus responsible for Cercospora leaf spot disease of sugar beet (Beta vulgaris). Plant pathogens such as C. beticola utilize “effector” molecules to aid in disease establishment. Effectors are generally small, secreted molecules that contribute to pathogen virulence. A culture filtrate infiltration study was conducted to identify potential effector molecules secreted by C. beticola. A variety of fungal growth conditions were pursued, one of which resulted in a necrotic phenotype when the culture filtrate was infiltrated into sugar beet leaves. The culture filtrate was fractioned using ion-exchange chromatography. Fractions were infiltrated to identify the protein responsible for necrosis. Five candidate necrosis-inducing effector proteins were identified through mass spectrometry analysis. Targeted gene disruption of these candidates and subsequent virulence assays revealed an increased virulence for Δ05663 strains compared to the inoculated wild-type. Full characterization of this candidate effector will shed light on the C. beticola-sugar beet interaction.