A Duke Energy experiment with using chemicals to keep tree limbs away from power lines has spurred complaints from homeowners concerned about environmental hazards and the health of their trees.
Workers are sweeping through Myers Park, Dilworth, Plaza Midwood and other leafy neighborhoods, injecting the soil surrounding trees with Cambistat, a product that stunts the growth of limbs.
Duke and the Minnesota-based manufacturer, Rainbow Treecare, insist that the product poses no threat to humans or pets. In fact, they say, it makes trees stronger.
But some residents are angry that workers showed up in their yards in recent weeks without warning. They contend that chemicals put into the soil could leach into groundwater or harm nearby plants and vegetable gardens.
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Jane Burts of Myers Park said she was startled when she saw a Duke Energy contractor inspecting a tree in her yard.
When she confronted the man, Burts said he told her that the chemical injection would slow the growth of trees and nearby plants. He also said that as a precaution, he would keep children and dogs from digging around the trees for a few days, Burts said.
“It doesn’t feel good,” said Burts, who refused to allow the worker to inject Cambistat. “There seems to be a lot of questions.”
Duke Energy spokeswoman Paige Layne acknowledged that the company made a mistake when it did not warn property owners that workers would come onto their property.
“The only thing I can do is apologize,” Layne said.
Asked about safety concerns, Layne said Cambistat has been approved by the U.S. Environmental Protection Agency.
Layne stressed that homeowners can decline to have the product used on trees on their property, saying Duke will consider discontinuing the injections if too many people opt out.
But workers do not need permission from residents to inject soil in the public right of way.
How Cambistat works
Charlotte is ranked among the top cities in the nation for urban forests, which experts say improve aesthetics, increase property values and save energy. Nearly half of the city has tree cover, and the City Council has set a goal to increase that number.
However, tall, mature trees threaten Duke Energy’s ability to deliver power to homes. The company sends workers to prune tree limbs that interfere with power lines, often enduring criticism from residents and high costs.
In response, the company has contracted with Rainbow Treecare to see whether chemical injections can reduce tree trimming in Charlotte, Greensboro and Durham, Layne said.
In Charlotte, she said, crews will inject soil in the Dilworth, Myers Park, Sedgefield and Plaza Midwood neighborhoods and along Park Road in south Charlotte.
Workers inject Cambistat into soil at the tree’s base, where it can be absorbed into the roots. Cambistat slows branch growth by 40 percent to 70 percent by altering a tree’s hormones, according to Duke and Rainbow Treecare.
Cambistat has been used safely across the country for more than a decade, said Tom Prosser, CEO and founder of Rainbow Treecare.
Prosser said the product is popular with arborists, who use it to heal unhealthy trees. Cambistat makes trees more tolerant of extreme heat and drought, he said.
Charlotte arborist Don McSween said city officials agreed last month to allow chemical injections on trees in the public right of way. McSween said he raised no objections since Cambistat was tested near the streets in west Charlotte several years ago.
But McSween said he might have more concerns about using the product on private property because plants near treated soil could have their growth stunted.
A Duke official recently spoke at a Freedom Park Neighborhood Association meeting to allay fears, said Mary Lou Buck, a board member.
Buck said the dozen or so people who attended the meeting were not convinced the chemical injection was safe.
“They are very frustrated about how it was handled,” because they felt Rainbow Tree couldn’t answer their questions, Buck said.
‘The right tree in the right place’
State environmental groups said they were unaware that Duke had launched the experiment.
Fawn Pattison, a senior advocate for Raleigh-based Toxic Free NC, said she is worried for Charlotte’s trees, which already suffer from the city’s poor air quality.
Told about claims that Cambistat makes trees strong and poses no threat to humans, Pattison said she is skeptical.
Dave Cable, director of TreesCharlotte, which promotes the city’s goal to have 50 percent tree coverage by 2050, said Duke is in a difficult position.
“The arborist rule is ‘the right tree in the right place,’ ” Cable said. “Unfortunately, we’ve got a lot of trees not abiding by that golden rule. Duke’s kind of up against the wall.”