All's fair in love and war.

that causes blast disease. First seen in Brazil, wheat blast last year caused devastating crop losses in Bangladesh. Inoue et al. tracked down the shifting genetics that have allowed the emergence of this potentially global threat to wheat crops (see the Perspective by Maekawa and Schulze-Lefert). Wheat varieties with a disabled resistance gene were susceptible to pathogen strains that affected oat and ryegrass crops. Subsequent genetic changes in the pathogen amped up the virulence in wheat. —PJH