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Managing Ultradwarf Bermudagrasses
James J.
Camberato, S. Bruce Martin, and Shane Parker
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TifEagle and Champion bermudagrasses have become popular in the
Carolinas as an alternative to TifDwarf. In the few years that these
ultradwarfs have been cultured, it has become apparent that best
practices for consistent success have not been determined. Some of our
ongoing research projects to ascertain these best management practices
are summarized below.
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Wetting Agents Reduce Localized Dry Spot and Improve Turf Quality of TifEagle |
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Ultradwarf bermudagrasses have higher shoot density and produce more thatch than TifDwarf. Managing water infiltration and movement into the root zone to avoid localized dry spot (LDS) is especially critical with the ultradwarfs. Localized dry spot occurs more frequently when greens are allowed to dry substantially between irrigations – precisely the watering schedule necessary to produce a high quality putting surface.
We examined the impact of rate and frequency of three Precision
Laboratories Incorporated wetting agents on the occurrence of LDS,
turf quality, and turf color. Treatments were surfactant A, B, and C
at 4 oz/1000 sq. ft. every 30 days, A, B, and C at 8 oz./1000 sq. ft.
every 60 days, A and C at 8 oz./1000 sq. ft. twice 10 days apart, and
an untreated control. Treatments were initiated on May 10, 2002 and
continued through September 2002. Turf LDS, quality, and color were
visually rated. Localized dry spot was rated as the percent of plot
area affected. Turf quality was rated on a scale of 1 to 9 with 1=bare
soil and 9=a dense, fine-bladed, and uniform turf. Turf color was
rated on a scale of 1 to 9 with 1=yellow and 9=dark green.
Wetting agents first enhanced turf quality and color, in comparison to
the untreated control, 42 days after initiating the experiment. Turf
quality averaged 6.5 for the seven treatments receiving a surfactant
treatment, but only 5.9 for the untreated control. Localized dry spot
affected 39% of the turf surface without a wetting agent application,
but less than 1% of the turf surface where a wetting agent had been
applied
(Photo 1). Turf
quality was higher with wetting agent treatments on 4 of 7 rating
dates over the next 40 days. Better turf quality, about 0.6 rating
units, and darker green turf color occurred with wetting agents even
when LDS was not evident.
Irrigation water infiltration rate into the turf was slow without
wetting agent (Photo 2).
Turf quality was lower where wetting agents A and C were applied
twice 10 days apart, than where these wetting agents were applied
on a 30 or 60 day interval. However, these differences in turf
quality were not detected until 66 days after the second
application in the twice only treatment, suggesting that the 8
oz./1000 sq. ft. application rate on a 60 day interval is
appropriate for optimum turf quality and LDS avoidance.
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Understanding the Impact of Fore+Chipco Signature on Ultradwarf Turf
Quality – |
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In previous research we found that an application of the fungicides Fore+Signature (pigmented formulations of mancozeb and fosetyl-Al) on overseeded bermudagrass in late March or early April substantially increased turf quality of the bermudagrass after transition. This improvement was documented in research consistently over the past 3 years. We wanted to know if we could obtain the same turf quality improvement with direct application to the bermudagrass in mid-summer. We also desired to determine how Fore+Signature increased bermudagrass turf quality. Potential factors affecting turf quality are disease control due to the fungicidal active ingredients, nutritional enhancement due to the manganese (Mn), zinc (Zn), or phosphite-phosphorus (P) coincidentally applied in the fungicides, or undetermined impacts due to the pigment included in the fungicide formulations.
In hope of separating out the effects of these three factors we
applied treatments of Zn, Mn, mancozeb and fosetyl-Al with pigment
(Fore+Signature) and without pigment (Pentathlon+Aliette), other
non-pigmented fungicides [Cleary 3336 (thiophanate methyl) and
Subdue Maxx (mefanoxam)] and an untreated control to Champion
bermudagrass on July 25, 2002. Nutrient application rates
corresponded to those applied in the fungicides - Mn at 0.08
lb/1000 sq. ft., Zn at 0.01 lb/1000 sq. ft., and P at 0.0657
lb/1000 sq. ft. mancozeb and fosetyl-Al containing fungicides were
applied at 8 and 4 oz/1000 sq. ft., respectively. Cleary 3336 was
applied at 6 oz/1000 sq. ft. and Subdue Maxx at 1 oz/1000 sq. ft.
All applications were allowed to dry on the turf surface except
Cleary 3336 which was watered in immediately after application.
Turf quality was rated on a scale of 1 to 9 with 1=bare soil and
9=a dense, fine-bladed, and uniform turf, three times in a 2 week
period after application.
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The turf exhibited symptoms of bermudagrass decline prior to treatment applications. Seven of the eight treatments producing the highest turf quality contained a pigmented fungicide, either Fore or Chipco Signature (Figure 1, Photo 3). These treatments typically had statistically better turf quality than the untreated control and effects were evident as early as 3 days after application. The improvement in turf quality was due to a greener, denser, and more uniform turf, not to simply a ‘paint’ effect of the pigment. The non-pigmented fungicides containing only mancozeb or fosetyl-Al, Pentathlon or Aliette, had no impact on turf quality. Application of Zn, Mn, and P at the same rate as applied in Fore and Signature also did not increase turf quality in comparison to the untreated control. Only one pigmented fungicide was necessary to optimize turf quality. Thus the impact of Fore and Signature on bermudagrass turf quality does not appear to be related to their fungicidal activity or nutritional content, but to the inclusion of pigment in the formulation. |
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Cleary 3336 was the only other treatment to substantially enhance turf
quality. Cleary 3336 is non-pigmented and does not have a significant
nutrient content. Perhaps the effects of Cleary 3336 were related to its
fungicidal properties. Cleary 3336 has been utilized for bermudagrass
decline management, previously. |
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Optimizing Root Zone Mixes –Under Construction |
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An 18,000 sq. ft. putting green will be built this fall at the Pee Dee REC in Florence to determine the optimum putting green root zone mix for establishment and maintenance of TifEagle and Mini-Verde bermudagrasses. Root zone mixes will vary in initial infiltration rate from 10 to 25 inches/hour and will be evaluated for 3 years after construction under high management conditions. Construction is underway and sprigging is expected in the spring of 2003. The Carolinas Golf Association is partially funding this research. Look forward to results at next year’s field day in Florence. Poster presentation at the Clemson University
Turfgrass Field Day, Sept. 10, 2002 |
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Highlights from Turfgrass Field Day 2002 Disease Management Bermudagrass Soil Amendments and Wetting Agents |
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