Poison ivy: double the size, double the trouble
Poison ivy on steroids? It’s serious science, but the weed wags are having a field day. Even the plant physiologist who predicts a greener, meaner and bigger breed of the three-leafed hazard jokes: “Soon it will be knocking on your bedroom windows.”
The scientist, Lewis Ziska, grew up in East Falmouth and remembers the aftereffects of an encounter with the infamous plant as a childhood rite of passage. He now works for the U.S. Department of Agriculture in Beltsville, Md. In a new study with Duke University recently published in Weed Science, Ziska and colleagues confirmed earlier predictions that poison ivy plants have doubled in size since the 1950s because of rising carbon dioxide levels. The ivy’s rash-producing oil is also more toxic. And if environmental trends continue, it will just get nastier.
Over the past 50 years, Ziska said, carbon dioxide levels have increased and poison ivy appears to have thrived. “It got bigger, faster,” he said.
Other plants like dandelions and honeysuckle have also bulked up with extra carbon dioxide, but poison ivy has enjoyed the biggest power boost so far. The plant’s vines became sturdier, the leaves larger and their oily residue more virulent. Rashes and blisters appear on the skin, and even swollen eyes can linger for weeks in the most sensitive people.
“What we did was look at records of the carbon dioxide levels going back to the 1950s,” Ziska said. “A relatively small increase of 100 parts per million – from 300 particles in the 1950s to 400 in recent samples – was a bonanza for the poison ivy plants. The leaves doubled in size with that relatively small change.”
By 2050, carbon dioxide levels are expected to increase another 100 ppm, to 500 ppm, and the leaves likely will become significantly larger, he said. Climate scientists also cite increasing amounts of carbon dioxide as a principal driver of global warming.
South Shore residents already have their hands full – or not, if they’re smart – with poison ivy. “It’s summer and it is everywhere,” said Wendy Fox, spokesman for the state Department of Conservation and Recreation.
Stephen and Deborah Little bought their home on Bunker Hill Lane on the edge of the Blue Hills Reservation in Quincy five years ago. They soon found their property, secluded and surrounded by woods, came with both deer, which they like, and poison ivy, which they spray, as it creeps up to their backyard borders and around the driveway.
“It’s literally everywhere,” said Stephen Little, a house painter. “You just live with it. I get a very itchy rash – it usually lasts up to 14 days.” He and his wife walk their dog in the woods and while he gets the rash, his wife Deborah said, “I’ve never had it, I must be immune.”
About 80 to 90 percent of the population is allergic to poison ivy, which causes an immune reaction in which white blood cells attack skin cells, causing the rash.
At Wompatuck State Park in Hingham, seasonal park supervisor Lucas Recore, 26, is very familiar with the wily weed.
Recore carries small yellow packets of a chemical skin protector in his pockets when he goes into the woods. He also gives them to others. The product claims to prevent or ease the rash after someone has been exposed and Recore says it works. On the bulletin board at the campground check-in office is a flier with illustrations and tips on of what the plant looks like.
“It’s all along the borders, you see it around the edges of the paths and roads, and we had one man come in to the office complaining about a really bad case,” he said. “We warn people to look for it.”
A quick trip around the campground recently turned up one couple who had been volunteer host campers for three-months. They had successfully avoided poison ivy during their visit. Another, younger couple said they wouldn’t know what it looks like.
Even though poison ivy is bad on the South Shore, it’s worse elsewhere.
“It’s nothing here like what I saw in the South,” said Recore, a Rhode Island native who has worked for the U.S. Forest Service all over the Southeast. “I’ve seen poison ivy vines so big they stand up by themselves, like trees – vines that are two inches around – but I’ve never seen it that bad here.”
The state tries to keep the hearty ivy at bay.
“It’s in all our parks and we try to control it in areas that are heavily used, like picnic tables and paths to the bathrooms,” Fox said. “The workers used to pull it out by the roots, but they were getting the rash, even with gloves, so now we spray it with a mild pesticide that has the chemical glycosate.
“That gets to the roots, and you have to spray the roots because if just the leaves and vines are cut off, it grows back,” she added. “It’s a survivor.”
Sue Scheible may be reached firstname.lastname@example.org.