Field Science
18 SportsTurf | March 2015 www.sportsturfonline.com
the concept and found it to be highly
effective. The sale of glyphosate tolerant
creeping bentgrass is still under review by
regulators in the US federal government
and to date, it has not been released.
This process is not without draw backs.
For instance, Poa annuacould develop
resistance to the glyphosate over time.
However, this remains the most promis-
ing technology that I have worked with
in my career and hopefully it will be
released in the future.
Scotts is currently developing gly-
phosate tolerant Kentucky bluegrass.
These cultivars are still under develop-
ment, but they may provide one of the
best opportunities for the selective con-
trol of Poa in Kentucky bluegrass sports
turf areas that have been available to date.
It is likely to be a few years before these
cultivars are ready for the market.
A potential 'non-chemical" method
that can offer some relief to the prob-
lem in Kentucky bluegrass fields is fraze
mowing, which quickly removes the
upper layer of soil, including Poa annua
seed, followed by reestablishment with
Kentucky bluegrass seed (Fig. 6). In 2014,
CSFM Tim Van Loo performed a success-
ful test of this procedure on one of Iowa
State's practice fields. While the objective
of this was not to control Poa, it is appar-
ent that this procedure can potentially be
used on older Poa-infested fields.
It is apparent that the removal of
Poa annua from any turf area is a very
complex issue. The solution varies with
a series of factors, including the primary
grass species on the field, climate, weather,
soil type, and location. There is no single
solution. The solution may require some
experimentation by the sports turf man-
ager to find the right solution for their
particular situation. ■
ST
Dr. Nick Christians is a professor of
horticulture at Iowa State University. His
area of research interest is in the develop-
ment of naturally occurring herbicides for
the turf industry. He also conducts research
on reducing the pesticide and fertilizer
input for the management of quality turf
in sportsturf, golf and lawn care industries.
For a list of citations for this article, visit
www.sportsturfonline.com.
T
Fig.6. Fraze mower used to remove grass
and the upper layer of soil from practice sports
field at Iowa State.
