A devastating cotton virus lurked undetected in U.S. fields for nearly 20 years

A damaging cotton virus thought to be a recent invader has actually been hiding in U.S. fields for nearly two decades. New research shows cotton leafroll dwarf virus was present as early as 2006, quietly spreading across major cotton-growing states long before it was officially identified. By reanalyzing old genetic data with modern tools, scientists uncovered a hidden history of the virus’s spread—including its first confirmed appearance in California and even traces in animal feed.