Tree Growth Regulators

Learn about how we maintain the health and safety of trees to improve service and safety for PGE customers

We’re fortunate to live in such a lush and green area, but did you know that fallen tree branches pose a risk to unplanned power interruptions?

To strengthen the energy grid and ensure safe, reliable service, we’re performing regular tree maintenance in your neighborhood across our service area.

You may see our contractor, T&S Growth Solutions, perform regular maintenance on trees within the power line rights of way. This work ensures the health and safety of the trees, helps keep you safe and improves the reliability of our power lines.

What are the benefits of TGRs?

Our licensed contractor may apply a product to a tree located in the power line rights of way called Cambistat to safely slow tree growth. TGRs help in reducing pruning needs and improves tree health, extending the life of the trees.

Trees treated with Cambistat vs. untreated trees are typically more tolerant to heat or drought, have deeper roots and greener foliage, which protects them from disease.


Photo credit: Rainbow Tree Company - Tree growth regulator - non-treated


Photo credit - Rainbow Tree Company: TGR - treated tree

What is Cambistat and how does it work?

  • Cambistat (Paclobutrazol), is a tree growth regulator approved for use by the Environmental Protection Agency.
  • Cambistat is applied to soil 4 to 6 inches beneath the ground at the base of the tree, allowing for optimal absorption. It is then transported to branch tips, where it works to slow the growth of twigs and branches, and redirect nutrients to the roots. Treated trees become more resistant to drought and disease. They also produce a greater amount of chlorophyll, resulting in darker green leaves.

What risk does Cambistat pose to groundwater?

The product has undergone extensive testing required by the Environmental Protection Agency and state agencies. It has been shown to have limited mobility in all soil types and stays bound to the soil until absorbed by the tree.

Can I use treated leaves for mulch?

Yes, leaves from treated trees can be used as mulch, bagged for disposal or composted.

Does Cambistat pose a risk to people, pets or wildlife?

Research shows that there is minimal risk when the product is applied as directed by licensed professionals.

Can I opt out of treatment?

Yes, the treatment is completely voluntary. If you wish to opt out or have additional questions, please call our contractor T&S Growth Solutions at 855-922-3810 or visit

Thank you for your patience as we improve reliable energy service for you.