Understanding how pathogens evolve is a fundamental component of learning how to protect ourselves and our world from pests and diseases. Yet we are constantly underestimating pathogen evolution, such as in the case of the COVID-19 pandemic, which some believed had been conquered until the arrival of the Delta variant. Similarly, we are often a step or two behind plant pathogens, which is why the question "How do pathogens evolve novel virulence activities?" was voted by scientists in the molecular plant-microbe interactions field as one of their Top 10 Unanswered Questions and explored in a review article recently published in the MPMI journal.
source https://phys.org/news/2021-09-pathogens-evolve-virulence.html