Although discovered in the United States only seven years ago, tar spot has wreaked havoc on corn yield—resulting in an estimated 1.2-billion-dollar loss in 2021 alone. The miscreant behind this devastating plant disease, Phyllachora maydis, is an emergent fungal pathogen whose biology remains obscure. This lack of understanding significantly limits disease management strategies, and no corn germplasm is completely resistant to the pathogen.