Right-Sizing Stem-Rust Research

Stem rust caused by Puccinia graminis f. sp. tritici is a potentially devastating fungal disease that can kill wheat plants and small grain cereals but more typically reduces foliage, root growth, and grain yields [e.g., ( 1 , 2 )]. After years of success in keeping the disease at bay, new virulent races (collectively referred to as “Ug99”) have emerged, with the potential to infect much of the world's wheat ( 3 ). Despite, or because of, the success of past research, these programs saw an eventual rundown in support ( 4 ). We estimate global wheat losses over the past 50 years absent investments in research to limit impacts of stem rust and discuss how this can inform decisions about “right-sizing” research investments.