Duke Energy to retard tree growth using chemicals

And Greensboro is going to be the lab rat:

Duke Energy chose Greensboro to be among three North Carolina cities where it will test a chemical product that slows tree growth, according to company leaders.

Rainbow Treecare will inject the “growth regulator” Cambistat into the ground near trees within Duke Energy’s rights of way, where branches can interfere with power lines. About 20 species of trees will be treated, including maples, elms, sweet gums and oaks, said Shawn Bernick, Rainbow’s vice president for research and development and technical support.

It's not surprising they would choose Greensboro as one of the test cities, as the Gate City has a very healthy canopy, at least in some of the older neighborhoods. It may be a first for Duke, but other utilities have used this approach to curb tree growth:

Several residents of the Homeland Neighborhood Association along Greenleaf Boulevard are resisting Indiana Michigan Power's effort to apply a herbicide to the trees to retard growth. Although the substance being used, Cambistat, is said to be safe, the neighbors are worried it will contaminate their well water.

Looking at a printout of Cambistat's label, Verna Brinson, who lives on Greenleaf, pointed to the ingredient listing. The active ingredient, paclobutrazol, comprises 22.3 percent of the product while the remaining 77.7 percent is identified only as "other ingredients." If it was just water, Brinson surmised, the makers would have put water on the label.

"I would rather they top the trees like that than put something into the ground," said Joanne Klopfenstein on Sundale Place. "The trees will grow out. They look funny for a year or so then they grow out."

Cambistat has been on the market since 2003 and is used by utilities and landscapers across the country, said Jim Neeser, national utility sales specialist at Rainbow Treecare Scientific Advancements, the company that makes Cambistat. The substance is ingested by the tree through its fine root system and then binds to the wood cell to stop the production of the growth hormone, gibberellic.

Neeser declined to disclose the additional chemicals. That is what makes Cambistat unique, he said, and publicizing those ingredients would be releasing proprietary information. However, he said, the U.S. Environmental Protection Agency knows the complete recipe and has tested and approved the product.

That "proprietary information" thing seems to be a common refrain from chemical companies. And as long as government lets them use it to conceal critical information from the public, they'll keep using it.


Pot growers ahead of the curve

The main chemical in this tree growth inhibitor has been marketed to cannabis growers for a few years, even though it's not supposed to be used on food crops:

Paclobutrazol is banned in most European countries while the US EPA lists it as “Moderately Hazardous” and states, “This substance has not undergone a complete evaluation and determination under US EPA’s IRIS program for evidence of human carcinogenic potential”. At this time it appears that Paclobutrazol has not been banned but has no food use registrations in the USA.

I encourage readers to investigate the use of PGRs in greater detail. It’s important to understand that these chemicals dramatically alter the natural behaviour of plants. PGR’s in comparable doses used different plant species can have very different effects. The exact biology of some of these complex hormone-like interactions is still under study. It’s possible that we will never fully understand the effects of PGRs on produce intended for consumption via combustion.

Not a "tree hugger"

I won't be chaining myself to trees, yet, but Duke just keeps giving me more reasons to despise them. They came through my neighborhood and just decimated the place. I'm 2 blocks from the interstate, and before, the street between me and the maelstrom of highway was a parklike, shaded, thickly treed wall of green. With no prior notice, they razed 2 to 3 foot round trees, buzzcut to the ground, for about a four block path, and now I have a lovely view of this bald scar and the highway beyond, and a substantial increase in the noise level. But hey, that pesky trimming cost won't cut into their profits any more. Tough shit that the city has gone to such lengths to get designated a "Tree City". Doesn't influence Duke's practices at all. Several friends in different areas complained of similar heavy handed butchering by Duke. They are both out of control and in control.

The timing is suspect

After our recent tribulations with power outages due to ice storms, I'm thinking Duke Energy saw an opportunity to ramp up their assault on trees, counting on a diminished public opposition to such behavior.

And they'll probably succeed.

Now we're going after tree cutting?

I am probably the biggest Duke Power basher on Earth. But, this discussion about Duke cutting tree limbs to keep people from losing power during bad storm periods is kind of ridiculous, in my view. If these same people lost power because the power company wasn't proactive in cutting away trees and limbs and even areas where future limbs would create power outages, they'd be hollering and screaming just as much as they are about cutting too many limbs and such.

"Assault on trees"? Why on Earth would Duke Power want to "assault" trees?

This looks more like just something to bitch and moan about for the sake of creating banter than anything.

Color me confused, I guess.

Color you a troll

And I have no problem with clear-cutting trolls off the BlueNC landscape.

Sorry folks. This should have been done some time ago, but it's not something to be done lightly, even if these things always turn out the same way.

Tree clearance

Duke Energy also uses contractors to do clearing of trees around power lines.

I have a friend in Greensboro who is a horticulturalist and came home a couple of weeks ago to find that a team of contractors for Duke Energy with Charlotte-based Aslundph had hacked an oak tree in his yard beyond recognition and tromped all over his flower beds. The guy on the Aslundph crew joked about "taking home some firewood".

My friend was incensed and called up Duke Energy about it. They were supposed to leave a notice that they would be working on his property and didn't. An inspector came out, apologized, and promised some kind of restitution.

My friend noted that they had been "hacking up" trees all around the neighborhood and doing real damage to them - it could have been done in ways that cleared the way for power lines and didn't damage the trees.

Duke Energy seems to be doing things on the cheap, getting cheap guys with chainsaws that really don't know what they're doing.

All the better to protect that massive shareholder profit, I suppose.

Big difference between pruning and butchering

Contrary to what the under-the-bridge dweller above was trying to claim, I have no problem with tree maintenance, if it's done right. But wholesale destruction and/or chemically inhibiting their growth is not "doing it right."

Roundup or its chemical relative

has been used for underbrush control for several years now. They used to cut the undergrowth but now they just hire third party chemical sprayers to kill everything. Disgusting to look at and can't be good for the environment.

Why don't they bury the lines underground? We have so many ice storms here and you can never tell which tree is going to take a line out.

As a practicing arborists,

As practicing arborists, our company has been responsibly using Cambistat on our clients properties for over a decade. Not only does it slow twig elongation, reducing the frequency Duke Energy needs to be in your yard pruning your trees, but it also induces positive physiological responses in the treated tree. These include; improved drought tolerance, greater fine root density, and an increase in a trees resistance to pests and diseases.

The product and application can sound scary out of context, but when applied correctly it can be good for trees. A little public outreach and education on the part of Duke would have gone a long way, seems like they fumbled the ball on this one.

Thanks for the information

A few questions:

1. Where are you "practicing" being an arborist? Does your company have a name?
2. Can you point us to studies confirming the field work you've witnessed?
3. What negative consequences have been associated with the product?

I'm not trying to be rude or skeptical, just looking for validation. We get all sorts of people around here claiming to be experts in this or that who often prove to be employed by companies with a financial stake in the issue.

In case Patrick doesn't come back,

it looks like this is where he works. Greensboro's Arborist made a similar comment about this treatment being healthy for trees, but I've yet to see anything about potential groundwater issues or any ill effects on local wildlife that may eat the seeds or the nectar from blooms and such.

Which is one problem with specialization: you tend to get a tight focus on your own bailiwick, and leave others to worry about areas outside your field. Not saying Patrick is doing that, but many who work in the agricultural field fall into that category.

It's time to go solar or wind....

These power companies can save big bucks by leasing solar cells or wind collectors. They could charge up to $200 per month for just maintenance. Knowing that the cost will be the same each month is good for the budget, going solar/wind will mean you still have power when the lines would normally go down! This will involve little tree trimming and they can stop using so much coal.

One thing that hasn't been mentioned in this thread

is the fact that inhibiting tree growth will lessen the carbon sequestration that trees do naturally. If trees don't grow they are not going to pull carbon from the environment. So in addition to the tons of carbon that Duke puts into the air generating power, they will now be limiting its removal through natural means. A lose-lose for the environment.

I actively oppose gerrymandering. Do you?

Please stop spreading mistruths.

I work for Rainbow Treecare - the company that is working with Duke to help make the pruned trees healthier. You need to go back and actually do research on this topic that you claim to be an expert on. Almost all of the facts you claim to be an expert on are mostly wrong and innaccurate. For instance - This product is widely used in the horticulture industry. It has more than 30 years of research. It is legally used in Europe on apples and other stone fruit. It is not toxic. In fact if you brush your teeth or use mouth wash - those compounds are more toxic. Hand soap? Dish Soap? and coffee are more toxic. Regarding your vegetable garden. Why would anyone apply this to their garden? It would NOT make the vegetables toxic. But would slow their growth down, increase their fibrous roots, increase the chlorophyll, and make more seeds or fruit in some cases. If you really want the truth - my recommendation is for you to CALL POISON CONTROL(704) 355-4000. Please stop spreading misinformation and creating fear in people. The facts are that this is very good for the trees and will help them be healthier and more resilient.

Regarding ground water - there is a lot of research on this and this tree health treatment does not move in the soil past where you put it more than a few Millimeters.

Speaking of mistruths:

...this tree health treatment does not move in the soil past where you put it more than a few Millimeters.

If you're going to flog your product here and accuse people of spreading misinformation, I'd suggest you try to avoid doing the same yourself:

Although characterized as moderately mobile in laboratory studies, no significant movement of
PBZ was detected in field studies in agricultural soils. In the orchard studies, PBZ residues
(parent plus degradate) were detected at 10% or less of total applied in soils with depths of 48
inches in the California study, 24 inches in West Virginia study, and 48 inches in the Florida
study. These depths are the maximum depths sampled at each study. No information was
provided on the nature or type of soils in the summary document. The PBZ ketone metabolite
was predominately detected in the subsurface soil layers, also at insignificant levels (U.S. EPA,

And it's not only leaching into the water table that concerns me. The streetside location of most of the proposed treatments means it's much more likely Cambistat will be introduced into our water resources via stormwater runoff, and these traits are bothersome to say the least:

PBZ is unlikely to volatilize to any significant extent owing to a low estimated vapor pressure.
The octanol-water partitioning coefficient (log KOW) of 3.2 indicates a potential for this chemical
to bioaccumulate in fish. A fish bioaccumulation study, which was only conducted for 14 days,
showed BCF factors of 20x for edible tissues (day 3), 248x for non edible tissues (day 3), and
44x for whole fish (day 10) (U.S. EPA, 2007B).

Laboratory studies indicated that PBZ is relatively stable to degradation by hydrolysis. More
than 94 percent of PBZ was still present after 30 d in pH 4, 7 and 9 solutions, respectively (U.S.
EPA, 2007B). PBZ did not undergo appreciable photolysis in water when exposed to light in pH
7 buffer. More than 96 percent of PBZ was still present after 10 d of exposure (U.S. EPA,
2007B). In the presence of light, degradation of PBZ in soil was slightly accelerated with a
calculated half-life of 188 d. It was concluded that soil photolysis is unlikely to be a significant
route of dissipation (EFSA, 2006).

Degradation in a water-sediment system was reported in EFSA (2006). The data indicate a low
degradation rate in both the water and the whole system. The half-life determined for the whole
system was 164 d, with most of the PBZ remaining in the water phase.

The research is mostly positive, with very low levels of toxicity. But that doesn't mean people have no reason for concern.

Yeah, and...

I also recall tales of product reps selling RoundUp who would drink shot glasses of the undiluted product to prove its safety about twenty years back when I spent a couple years in the nursery/landscaping business, The science now clearly indicates that Monsanto's flagship product is anything but safe. That might be an apples and oranges comparison, but it is what it is.

I would much rather see them in my yard every year trimming trees, even if it made my bill go up slightly, than have them come through like my local co-op did last year and spray herbicide everywhere, including in my pond.


"...the question is not whether we will be extremists, but what kind of extremists we will be."

Martin Luther King, Jr., Letter from Birmingham Jail