After a wet spring, poison ivy is “growing like crazy,” says former Ann Arbor parks planner Gerry Clark. Besides the rain, some believe that nature’s three-leaved pest has been multiplying for reasons that range from global warming to less frequent mowing. Since the U-M Arboretum went from mowing every couple of weeks to once or twice a year, says director Bob Grese, “we definitely see it crop up in new places.”
While the Arb’s motivation is ecological, the city is mowing less as a cost-cutting measure. “I can’t think of a park that doesn’t have poison ivy,” says parks staffer Jason Tallant. There’s a particularly fine crop along the Border-to-Border Trail just below Argo Dam–anyone stepping off the path there is asking for an itchy encounter.