Late blight is a potentially destructive disease of potato and tomato crops worldwide. While the disease has been studied by many researchers for more than a century, changes within the Phytophthora infestans pathogen population have required further in-depth investigation for management. Since 2009, a group of newly identified genotypes/clonal lineages/strains of the pathogen have been identified, and US-23 has become the most predominant in both tomato and potato production areas of the continental United States. 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.