Williams roams Connecticut's woods armed with a propane torch to incinerate clumps of Japanese barberry, an invasive plant species that chokes off native vegetation and provides a favorite habitat for ticks.

WSJ: This Season's Ticking Bomb

But new research found that, like stem rust, stripe rust increases its genetic variability by reproducing sexually on the leaves of another host plant (the barberry), making itself more adaptable and more deadly.

ECONOMIST: Wheat rust and world farming