the Fate of Field Paspalum Control - The Paginator

GREEN LIGHT ON GOLF
Managing Summer
Decline
in a Creeping
Bentgrass Green
By Peter H. Dernoeden, Ph.D., and C. P. Ryan, Dept. of Plant Science and Landscape Architecture, University of Maryland
Previous studies have documented
improved summer performance
of creeping bentgrass (Agrostis
stolonifera) putting greens treated with
selected fungicides even in the absence
of disease. Chipco Signature, especially
when tank-mixed with either Daconil
or Fore Rainshield, has been associated
with color enhancement and
improved cover and quality. Mancozeb
was shown to mitigate scalping in
“puffy” putting green turf in summer
(Dernoeden and Fu, 2008). Other
studies have demonstrated the superior
ability of spoonfeeding with urea to
improve summer quality of putting
greens, when compared to biostimulants,
chelated iron and micronutrient
products (Settle and Dernoeden, 2009).
The non-disease-related benefits
provided by some fungicides and urea
are said to reduce summer decline.
Summer decline of creeping bentgrass
greens normally occurs in response
to high-temperature stress combined
with mechanical injury and sometimes
diseases. Additional information
regarding summer decline management
with other products is warranted.
The objective of this study was to
assess various fungicides, as well as
Super Stimulant (organic peat humates;
6% humic acid) and Nano Argentum
(elemental silver in osmotized water
applied at 41 ml/acre), applied alone
and/or tank-mixed with another compound,
for their ability to improve the
summer quality of a creeping bentgrass
putting green turf. Urea was applied in
a spoonfeeding program and served
as the standard for comparison.
Our research methods
This field study at the University
of Maryland Paint Branch Turfgrass
Research Facility in College Park
was conducted on an 80/20 sand/
sphagnum peat moss (v/v) creeping
bentgrass putting green constructed to
USGA specifications. The area was a
mature stand of ‘Declaration’ creeping
bentgrass. The study area was fertilized
with 2.5 lbs. N/1,000 ft 2 from mostly
20-20-20 between September 20 and
November 11, 2009. The bentgrass
received an additional 0.5 lb. N/1,000
ft 2 from 20-20-20 in April and May
2010. Thereafter, the study area
received no additional nitrogen, except
for that provided by the urea spoonfeeding
treatment.
The turf was mowed five times
weekly to a height of 0.150 inches and
otherwise was maintained as a putting
green. To induce mechanical stress,
lower mowing heights were imposed
on three dates in July, as described
below. During the study period, daytime
high temperatures generally
exceeded 90ºF, and nighttime temperatures
seldom fell below 68ºF. The
site was irrigated to prevent drought
stress and was syringed as needed.
Treatments were applied three times
on a two-week interval on June 15,
June 29 and July 13, 2010. Turfgrass
quality was rated visually on a 0 to
10 scale, where 0 = brown or dead
26 MTC TURF NEWS