PLANT HEALTH CARE
32 May/June 2016 Landscape and Irrigation www.landscapeirrigation.com
What's your type?
First, let's step back and revisit the science of how these products
work to understand the uses or benefits that they can provide.
At the time of my inaugural summer of scientific employment,
plant growth regulators (PGRs) had been around for quite some
time. In fact, plant physiologists had already classified PGRs into
two main categories based on how they accomplished growth
control. The first group was known as Type I growth regulators.
Normally, as a plant grows, it increases its total number of
cells by dividing them through the process of mitosis. One cell
becomes two, two cells become four, and so on. Type I regulators
(mefluidide, maleic hydrazide, and others) work by essentially
blocking this process. This technology proved very useful in
certain applications, particularly in places such as fruit tree
orchards, where they are frequently used to prevent sucker twig
growth off a grafted rootstock.
Although they are very useful in agriculture, they have some
issues when utilized in ornamental landscapes. Preventing
mitosis can cause irregular growth patterns in the new tissue as it
develops. This was not an issue for orchard use; but in landscape
settings, where aesthetics are paramount, clients have been
■ BY BRANDON GALLAGHER WATSON
Just over a decade ago, I got my first job in the science of
arboriculture. Sure, it was a lowly internship as a research
assistant, but it got me out in the field, setting up trials and
doing treatment evaluations. That first summer, my company
was doing extensive rate development trials for a shrub growth
regulator. The company had already found success developing a
product for predictably reducing tree growth, and was interested
in expanding that technology to shrubs. At the time, the focus was
on better understanding the science behind how these treatments
worked and why certain shrub species were responding strongly
to the treatments while others seemed unfazed.
Now, more than a decade later, the functionality of growth
regulation is well understood, and predictable rates have been
determined for hundreds of different species. As a result, much
of the focus on shrub growth regulators has shifted from a
scientific inquiry to a business inquiry. How can this technology
be used by landscape maintenance professionals in ways that
either add up to savings for service providers or a benefit to the
clients? We'll take a look at three different ways companies are
implementing growth regulators and finding new uses everyday.
Three Ways Growth Regulators
Can Change Your Shrub Game
This hedge row was trimmed
and then treated with PGR,
and still held its shape more
than a month later.
