USDA research shows that climate change is making poison ivy bigger and badder than ever.
Since the 1960s, poison ivy, Toxicodendron radicans, has both doubled in potency and average leaf size. The tiniest amount of urushiol, the oil inside poison ivy’s shiny green leaves, causes unbearable itching as the oil penetrates the skin and, as the chemistry of the oil changes, the likelihood of developing an allergic rash has greatly increased. It seems that the oil is in the leaf as a water repelling adaptation rather than a poison – no consolation for the poor sap who touches the sap!
Woodland trees will also be more susceptible to choking by rampant ivy growth, as poison ivy trials show it thrives in high CO2 environments. Research in South Carolina has also found that poison ivy is one of the few native plants there to be increasing its range.
Quick and thorough washing with special soaps or detergents is the only way to remove the urushiol from the skin before a wildly itchy and painful rash develops, often lasting for several weeks. Gardeners are particularly vulnerable. Chemists at the University of Californai Santa Cruz are developing a fluorescent compound that can attach to the oil so it can be seen on the skin under black light.