Initially developed for turf and floriculture, tree growth regulators (TGRs) were later adopted in utility arboriculture to reduce how often pruning is required.
Using Tree Growth Regulators to Enhance Tree Health and Worker Safety in Arboriculture Managing Urban Trees with TGRs By Patrick Anderson and Dane Buell
Tree growth regulators (TGRs) have quiet- ly become one of the most adaptable tools in the arborist’s kit. Originally developed for turf and floriculture, they later gained traction in utility arboriculture as a way to reduce pruning frequency. Today, they are widely used in landscape manage- ment, where arborists continue to expand the ways these products support healthier, more resilient trees in the urban and subur- ban environment. WHAT ARE TREE GROWTH REGULATORS? Modern TGRs, such as those containing paclobutrazol, work by modifying hormone production in the plant. Their primary ef- fect is blocking the synthesis of gibberellin – the hormone responsible for cell elonga- tion and expansion. When gibberellin pro- duction is suppressed, both primary growth (twig elongation) and secondary growth (trunk diameter) slow dramatically. Importantly, cell division continues. The plant still produces the same number of
cells, but they are smaller, resulting in a measurable reduction in growth. For many species – excluding certain members of the Pinaceae family – this can mean 30 to 70 percent less twig and diameter growth for two to three growing seasons.
Cambistat® by Rainbow ECOSCIENCE is a tree growth regulator that slows the vegetative growth of trees.
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