Page 11 - February 2022 Newsletter

C O U R S E U P D A T E

F R O M D I R E C T O R Y

O F A G R O N O M Y

N O A H G E S S L E R

Turfgrass Growth Regulators and Poa Control

There are two major classifications of turfgrass, warm season and cool season.
Creeping bentgrass and perennial ryegrass are both cool season grasses that do well in
our desert climate under the right conditions and management practices. A third cool
season grass can also be present in both bentgrass and ryegrass, but it not desirable.
Poa annua, or annual bluegrass, can invade both bentgrass and ryerass and
necessitate control.

The physiology of all cool season grasses is the same and therefore controlling one
growing within the others is limited primarily to different growth regulators. Growth
regulators limit or manipulate the growth of turfgrass by affecting how they produce
and use energy. Some are stronger than others and some can even cause negative
effects on warm season turfgrass varieties, such as bermudagrass.

We typically use three different growth regulators to control poa in bentgrass and
ryegrass, and they can even be mixed in the same application and at different rates
depending on the amount of poa present and the relative strength of the desirable
turfgrass. These growth regulators have an impact on both the poa and the bentgrass
or ryegrass. Control can gradually be achieved as the product regulates the growth of
the poa more than the others, and the desirable turf can slowly gain a competitive
edge. Another advantage of certain products is that they can limit the development of
seed head production in the poa, which can help control future populations.

After overseeding we can apply one particular product to control all the turf growth,
but we must wait until the bermudagrass reaches a fully dormant state until we can
apply a second product. The use of this product must also be stopped as soil
temperatures warm up in the spring to avoid causing problems for the bermudagrass
as it begins to wake from dormancy.

Bermudagrass in and around bentgrass greens is not desired, and so we are able to
apply multiple products to greens throughout the year. In recent years this has helped
greatly reduce the amount of poa in our greens. The significantly smaller acreage of
greens on the course in relation fairways and roughs also makes it much easier to treat
at this frequency.

Poa is a highly adaptable turfgrass that can be present in different amounts each year.
Weather plays a key factor in the establishment of poa in relation to the overseeded
ryegrass. Different control strategies need to be looked at each year to work to control
poa. Over time, the turfgrass industry continues to see changes to the products on the
market available for control.

Thank you,
Noah Gessler
Director of Agronomy
ngessler@gcdovemtn.com