Late blight is a potentially destructive disease of potato and tomato crops worldwide. While the disease has been studied by many for over a century, changes within the Phytophthora infestans pathogen population have required further in depth investigation for management. From 2009 to the current, a group of newly identified genotypes/clonal lineages/strains of the pathogen were identified, with US-23 becoming most predominant in both tomato and potato production areas of the continental U.S. This presentation will offer new information on the characterization of US-23 and other newer clonal lineages as it pertains to pathogen persistence and management. Further, a process for integrated late blight management, established for Wisconsin, will be shared to aid practitioners in understanding critical concepts of the pathogen and fungicides to enhance overall disease management.