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Improvement of the Spring Transition of Overseeded Bermudagrass

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					Improvement of the Spring Transition of
Overseeded Bermudagrass Putting Greens
        in the Coachella Valley



R. Green, G. Klein, F. Merino, J. Evans, M. Henry, S. Cockerham

                      in cooperation with

                Lane Stave and Will Friedner
                Desert Horizons Country Club



A research project conducted for the Hi-Lo Desert Golf
         Course Superintendents' Association


                    September 1996 to July 1998




                                                             UCR
                                                             TURF
                  ACKNOWLEDGMENT
A   ppreciation is given to the Hi-Lo Desert GCSA for funding this
research. Thanks also are given to Lane Stave and Will Friedner for
their willingness to provide a site and manage the turfgrass for this
research. The seed donated by Hi-Tech Irrigation and the fertilizer
donated by J.R. Simplot is also greatly appreciated. Thanks also to the
Agricultural Operations Department at the University of California,
Riverside for designing and building the putting green traffic simulator.




                                     1
                                                            INTRODUCTIONz

The spring transition of overseeded bermudagrass putting greens back to a monostand of bermudagrass is
a concern and a challenge for golf course superintendents in the Coachella Valley. Actually, the spring
transition is a common concern of golf course superintendents across the southern region of the United States.


Numerous articles concerning the overseeding of warm-season turfgrasses have been published in technical
and trade journals. A review of selected reports, including a brief description of the work and the findings
is presented in Table 1. General comments concerning the information in this review are listed below.


1. A strong, healthy bermudagrass is essential for a rapid spring transition. Healthy rhizomes, roots, and
      bud tissue associated with the crown are characteristic of a healthy bermudagrass prior to spring growth.
      Freezing, traffic, and extremely low mowing heights are examples of the numerous factors attributed to

      plant stress which can result in weak bermudagrass prior to spring growth. It should be noted that
      freezing stress may not be a dominant plant stress factor in the Coachella Valley and that relatively low

      mowing heights may be the standard for this region. Maintaining a strong, healthy bermudagrass in late
      summer and fall is recommended to help provide for a strong, healthy bermudagrass in the following

      spring. Recommendations for maintaining a strong, healthy bermudagrass in the fall normally involve
      good nutrition, higher heights of cut, and the least disruptive renovation practices.


2. Spring transition occurs when air and soil temperatures favor the growth of bermudagrass and discourage
      the growth of the cool-season overseed turfgrass. One paper reported that spring transition naturally
      occurs when soil and air temperatures are above 80ºF, when ryegrass roots begin to decline; while a
      second paper reported that competitive bermudagrass growth is associated with air and soil temperatures
      at about 90ºF.         A third paper recommended that mowing heights should be lowered when night
      temperatures approach 60ºF. Though mowing heights are relatively low in the Coachella Valley, there
      is the possibility of coordinating the timing of other practices which hasten the spring transition to a
      threshold nighttime temperature.                 Cultural practices would then be employed when air and soil
      temperatures favor the growth of bermudagrass and discourage the growth of the cool-season overseed
      turfgrass.


z
    From: Progress Report: Improvement of the spring transition of overseeded bermudagrass putting greens in the Coachella Valley.

February 10, 1998. Also, a revised edition of the review was published in Turf Tales Magazine, Vol. 5 No. 3 (Summer 1998).


                                                                        2
3. There have been numerous studies employing spring-applied treatments to hasten the bermudagrass
    transition.   Unfortunately, the majority of the findings from these studies are not consistent.       The
    treatments that have been tested include: core cultivation; vertical mowing; topdressing; scalping; vertical
    mowing and scalping; applications of nitrogen; applications of herbicides; and applications of plant growth
    regulators. No doubt, successful and consistent adoption of spring-applied treatments to hasten the
    bermudagrass transition will require timing based on soil and air temperatures.


4. Genetic variation for spring/summer persistence among overseed turfgrass has been reported.             It is
    probable that there is genetic variation among cultivars of poa trivialis.


Recently, there has been a trend in the Coachella Valley towards a less severe fall renovation and
overseeding of bermudagrass putting greens. The expectation is that these practices will result in a more
rapid spring transition. Techniques being used to reduce the severity of fall renovation and overseeding
include: applying Primo plant growth regulator to reduce bermudagrass growth in the fall; using higher
scalping rates and therefore leaving more green stubble; not applying diquat on putting greens; and withholding
irrigation for a shorter duration of time.


Due to the current interest of reducing the severity of fall renovation and overseeding to hasten the spring
transition, a two-year study was developed to test treatments related to fall renovation and overseeding that
would result in the fastest bermudagrass green coverage during the following spring and summer season.




                                                        3
                       OBJECTIVE

To test factors related to fall renovation and overseeding that
would result in the fastest bermudagrass green coverage
during the following spring and summer season.


                      HYPOTHESIS
The less severe the bermudagrass renovation in the fall, the
more rapid the bermudagrass green coverage should be in
the following spring and summer season.




                               4
                       Research Site

Location: Desert Horizons Country Club, Indian Wells, CA
Cultivar: Tifgreen bermudagrass (nursery plot)
Establishment: July 1989 (from stolons)
Root zone:   Six-inch imported sand placed over native soil
             (imported sand was a topdressing mixture that
             was within USGA specifications). No drain tile
             was installed.
Soil analyses (0- to 4-inch depth, taken on 7-22-98):
Sand:   88%             ECe:       0.78 dS? -1 (500 TDS)
                                           m
Silt:   11%             CEC:       4.5 meq/100g
Clay:   1%              SAR:       1.5
OM:     0.56%           ESP:       1%
pH:     7.7




                               5
Treatment Factors, Associated with Fall Renovation, that
  were Tested for Their Effect on Bermudagrass Green
 Coverage During the Following Spring/Summer Season

                               Treatment application date
Treatment factor
                                1996-97         1997-98
1. Chemical application         Sep. 27         Sep. 22
2. Scalping level               Oct. 04         Sep. 29
3. Seed rate                    Oct. 12         Oct. 10




                           6
                               Chemical Treatments

Applied to 6 x 10 ft subplots†:
1. Check (no chemical applied)
2. Reward (1 qt/acre)
3. Primo 1 EC (0.75 oz/1000 ft2)
4. Primo 1 EC (0.25 oz/1000 ft2)
†
    Finish spray volume = 2.0 gallons/1000 ft2.




                                                  7
                  Scalping Level Treatments

Applied to 10 x 24 ft main plots:

1. "Stubble"   (41% average bermudagrass green coverage on day of scalping
   in 1997).
   •   Verticut 3 passes, triplex, 0.125 inch bench ht.
   •   Sweep
   •   Mow, triplex, 0.110 inch bench ht.
   •   Verticut, triplex 0.125 inch bench ht.
   •   Sweep

2. "Dirt"   (2% average bermudagrass green coverage on day of scalping in
   1997).
   •   Verticut 3 passes, triplex, 0.125 inch bench ht.
   •   Sweep
   •   Mow, triplex, 0.110 inch bench ht.
   •   Verticut, triplex 0.125 inch bench ht.
   •   Sweep
   •   Mow, walk-behind, 0.100 inch bench ht.
   •   Sweep
   •   Mow, walk-behind, 0.100 inch bench ht.




                                    8
                             Seed Rate Treatments

Applied to 5 x 6 ft sub-subplots:
   1. HIGH SEED RATE
                                                                   Pure Live Seed
   Year       Cultivar / species               Actual seed rate
                                                                     (PLS) rate
              Seville perennial ryegrass             40.0                35.8
   1996-97
              Sabre poa trivialis                    10.0                9.4
              Seville perennial ryegrass             40.0                35.8
   1997-98
              Sabre poa trivialis                    12.6                9.4


   2. LOW SEED RATE
                                                                   Pure Live Seed
   Year       Cultivar / species            Actual seed rate
                                                                     (PLS) rate
              Seville perennial ryegrass            25.0                22.3
   1996-97
              Sabre poa trivialis                   10.0                 9.4
              Seville perennial ryegrass            25.0                22.3
   1997-98
              Sabre poa trivialis                   12.6                 9.4


Note: Plots topdressed before and after seeding to a depth of approx. 3/32 inch.




                                           9
Research plot plan for the improvement of the spring transition of overseeded bermudagrass putting greens in
the Coachella Valley at Desert Horizons Country Club, Indian Wells, CA.
                                                                                                                                                                                                                    N
                                    I                                                   II                                                   III                                            IV
                   Scalp: Dirt           Scalp: Stubble               Scalp: Dirt            Scalp: Stubble                  Scalp: Dirt           Scalp: Stubble        Scalp: Stubble           Scalp: Dirt

                    A         B               A         B              B           A             A        B                   A         B            A       B                A         B            B         A
         6'




              1          2               3         4              5           6              7        8                  9         10          11         12             13        14           15        16
                    A         B               A         B              B           A             A        B                   A         B            B         A              A         B            A         B
         6'
   24'




              17         18              19        20             21          22         23           24                 25        26          27         28             29        30           31        32
                    B         A               B         A              A           B             B         A                  A         B            A         B              A         B            B         A
         6'




              33         34              35        36             37         38          39           40                 41        42          43         44             45        46           47        48
                    B         A               B         A              A           B             A        B                   B         A            A       B                B         A            B         A
      6'




              49         50              51        52             53          54         55           56                 57        58          59         60             61        62           63        64
                                    1'                                                  1'                                                    1'
                5'            5'              5'        5'             5'          5'            5'        5'                 5'        5'           5'        5'             5'        5' 1'        5'        5'

                                   21'                       3'                                                     3'                       21'                    3'                      21'
                                                                                                                93'

 Scalping level treatments                                                        Chemical treatments                                                                      Seed rate treatments
  (24 ft x 10 ft main plots)                                                      (6 ft x 10 ft subplots)                                                                (6 ft x 5 ft sub-subplots)
         • Dirt                                                             Reward                                       Primo 0.75                        A: (35.8 lb PLS perennial ryegrass +
         • Stubble                                                                                                                                            9.4 lb PLS P o a tr ivia lis )/1000 ft²
                                                                            Primo 0.25                                   Check                             B: (22.3 lb PLS perennial ryegrass +
                                                                                                                                                              9.4 PLS lb P o a tr ivia lis )/1000 ft²
                                                                                                               10
                    Plot Management Protocol

Mowing:       Daily mowing with walk-behind greens mower set at
              heights ranging from 0.312 to 0.085 inches, and usually
              set at about 0.115 inches (less than 1/8 inch).
Fertilization: 0.3 lb N/1000 ft² per 3 weeks, using Microgreen 15-5-8.
Irrigation:   Irrigated to avoid drought stress and overwatering;
              irrigation source was well water.
Pesticides:   Pesticides were applied as needed (included Subdue 2G,
              Merit 75WP, and Dursban 50W).

Traffic:      Traffic was applied with a specially-constructed traffic
              simulator.

              The amount of traffic was visually estimated to be
              similar to the amount of foot traffic on the putting greens
              located at the GC.

              Normally, traffic was applied at a rate of 1 pass/day,
              3 days/week.




                                   11
                           Measurements

1. Percent Bermudagrass Green Coverage:
Ratings taken with two, 4 x 4 inch, subsamples from representative
portions of each sub-subplot. Percent of openness within the subsample
was also noted as necessary. Ratings taken every 3 weeks.

2. Putting Green Visual Quality for an Overseeded Bermudagrass:
Ratings taken on a 1-9 scale, with 9 = best, 5 = minimally acceptable,
and 1 = worst putting green quality. Ratings taken every 6 to 10 weeks.

3. Air Temperatures:
On-site air temperatures were taken hourly with a data micrologger pro-
tected from the direct light of the sun.

4. Soil Temperatures:
On-site soil temperatures were taken hourly with a data micrologger
sensor installed 2 inches below the soil surface of the research plot.

5. NOAA/National Weather Service Air Temperatures:
Historical 30-year (1961-1990) averages air temperatures were obtained
from the National Weather Service in Indio, CA.




                                  12
                    Calendar of Major Activities
DATE             ACTIVITY
                                            SEASON 1

Sep. 27, 1996    Chemical treatments applied.
Oct. 4, 1996     Scalping treatments applied.
Oct. 12, 1996    Seed treatments applied.
Oct. 20, 1996    Initial mowing: 0.312 inches (5/16 inches).
Oct. 23, 1996    Initial fertilization. Fertility regime set to 0.3 lb N/1000 ft2 with Microgreen 15-5-8 every
                 three weeks.
Nov. 8, 1996     Desert Horizons Country Club opens its course for play
                 Mowing height: 0.141 inches.
Dec. 20, 1996    Initial traffic applied. Traffic regime set to 1 pass/day, 3 days/week.
Feb. 20, 1997    Initial rating for percent bermudagrass green coverage. Ratings subsequently taken every
                 three weeks. Mowing height: 0.110 inches.
July 7, 1997     Traffic regime halted.
                 Final application of Microgreen fertilizer.
July 29, 1997    Final ratings for percent bermudagrass green coverage.

                                            SEASON 2
Sep. 22, 1997    Chemical treatments applied.
Sep. 29, 1997    Scalping treatments applied.
Oct. 10, 1997    Seed treatments applied.
Oct. 18, 1997    Initial mowing: 0.312 inches (5/16 inches).
Oct. 24, 1997    Initial fertilization. Fertility regime set to 0.3 lb N/1000 ft2 with Microgreen 15-5-8 every
                 three weeks.
Nov. 1, 1997     Desert Horizons Country Club opens its course for play.
                 Mowing height: 0.140 inches.
Nov. 11, 1997    Initial rating for percent bermudagrass green coverage. Ratings subsequently taken every
                 three weeks. Mowing height: 0.125 inches.
Nov. 17, 1997    Initial traffic applied. Traffic regime set to 1 pass/day, 3 days/week.
Dec. 2, 1997     Initial rating for putting green visual quality. Ratings subsequently taken every 6 to 10
                 weeks.
June/July 1998   Traffic regime halted.
July 1, 1998     Final rating for putting green visual quality.
                 Final application of Microgreen fertilizer.
July 22, 1998    Final ratings for percent bermudagrass green coverage.

                                                    13
           RESULTS:
Improvement of the Spring Transition of
Overseeded Bermudagrass Putting Greens
        in the Coachella Valley




                   14
Percent bermudagrass green coverage from 2-20-97 to 7-07-97 for four chemical treatments,
two scalping level treatments, and two seed rate treatments that were applied to a Tifgreen
bermudagrass nursery during fall 1996.
                                 100
                                                                                        CHEMICAL TREATMENTS, applied 9-27-96
                                                                                      (averaged over scalping level and seed rate treatments)
   % bermuda green coverage




                                 80


                                 60


                                 40
                                                                                                                                                                                                              Check
                                                                                                                                                                                                              Primo 0.25
                                 20                                                                                                                                   *                                       Primo 0.75
                                                                                                                                                                                                              Reward
                                  0

                                 100
                                                                            SCALPING LEVEL TREATMENTS, applied 10-04-96
    % bermuda green coverage




                                                                                             (averaged over chemical and seed rate treatments)
                                  80
                                                                                                                                                                                                                                     **
                                  60


                                  40


                                  20                                                                                                                                                                                        Dirt
                                                                                                                                                                                                                            Stubble
                                   0
                                 100
                                                                                    SEED RATE TREATMENTS, applied 10-12-96
      % bermuda green coverage




                                                                                    (averaged over chemical and scalping level treatments)
                                  80


                                  60


                                  40

                                                                                                                                                                                 25 lb rye /10 lb poa
                                  20
                                                                                                                                                                                 40 lb rye /10 lb poa

                                   0
                                                                                              09-Jan
                                                                                                       21-Jan
                                                                                                                02-Feb
                                                                                                                         14-Feb
                                                                                                                                  26-Feb




                                                                                                                                                                                                          02-Jun
                                                                                                                                                                                                                   14-Jun
                                                                                                                                                                                                                            26-Jun
                                                                  04-Dec
                                                                           16-Dec
                                                                                    28-Dec




                                                                                                                                           10-Mar
                                                                                                                                                    22-Mar
                                                                                                                                                             03-Apr
                                                                                                                                                                      15-Apr
                                                                                                                                                                               27-Apr
                                                                                                                                                                                        09-May
                                                                                                                                                                                                 21-May
                                       29-Oct




                                                                                                                                                                                                                                     08-Jul
                                                                                                                                                                                                                                              20-Jul
                                                10-Nov
                                                         22-Nov




                                                                                                                         Date (1996-1997)

*, **, *** Significant at P ≤ 0.05, 0.01, and 0.001, respectively.
                                                                                                                                   15
Percent bermudagrass green coverage from 11-11-97 to 7-22-98 for four chemical treatments,
two scalping level treatments, and two seed rate treatments that were applied to a Tifgreen
bermudagrass nursery during fall 1997.
                                 100
                                                                                        CHEMICAL TREATMENTS, applied 9-22-97
                                                                                       (averaged over scalping level and seed rate treatments)
     % bermuda green coverage




                                  80


                                  60


                                  40
                                                                                                                                                                                                                   Check
                                                                                                                                                                                                                   Primo 0.25
                                  20
                                                                                                                                                                                                                   Primo 0.75
                                                                                                                                                                                                                   Reward
                                   0
                                 100
                                                                              SCALPING LEVEL TREATMENTS, applied 9-29-97
   % bermuda green coverage




                                                                                             (averaged over chemical and seed rate treatments)
                                 80


                                 60


                                 40


                                 20                                                                                                                                                                                           Dirt
                                                                                                                                                                                                                              Stubble
                                  0
                                 100
                                                                                    SEED RATE TREATMENTS, applied 10/10/97
      % bermuda green coverage




                                                                                    (averaged over chemical and scalping level treatments)
                                  80


                                  60


                                  40


                                  20                                                                                                                                              25 lb rye /10 lb poa
                                                **                                                                                                                                40 lb rye /10 lb poa

                                   0                                                           **
                                                                                              09-Jan
                                                                                                       21-Jan
                                                                                                                02-Feb
                                                                                                                         14-Feb
                                                                                                                                  26-Feb




                                                                                                                                                                                                          02-Jun
                                                                                                                                                                                                                   14-Jun
                                                                                                                                                                                                                            26-Jun
                                                                  04-Dec
                                                                           16-Dec
                                                                                    28-Dec




                                                                                                                                           10-Mar
                                                                                                                                                    22-Mar
                                                                                                                                                             03-Apr
                                                                                                                                                                      15-Apr
                                                                                                                                                                               27-Apr
                                                                                                                                                                                        09-May
                                                                                                                                                                                                 21-May
                                       29-Oct




                                                                                                                                                                                                                                     08-Jul
                                                                                                                                                                                                                                              20-Jul
                                                10-Nov
                                                         22-Nov




                                                                                                                         Date (1997-1998)

*, **, *** Significant at P ≤ 0.05, 0.01, and 0.001, respectively.
                                                                                                                                   16
Putting green visual quality from 12-02-97 to 7-01-98 for four chemical treatments, two
scalping level treatments, and two seed rate treatments that were applied to a Tifgreen
bermudagrass nursery during fall 1997.
                                                                            9

                                                                            8
  Putting green visual quality
                                  Scale 1-9, 9=best putting green quality




                                                                            7

                                                                            6

                                                                            5

                                                                            4                                                                                                                                                                            Check
                                                                                                                                                                                                                                                         Primo 0.25
                                                                            3
                                                                                                                                                                                                                                                         Primo 0.75
                                                                                                   CHEMICAL TREATMENTS, applied 9-22-97
                                                                            2                     (averaged over scalping level and seed rate treatments)                                                                                                Reward

                                                                            1

                                                                            9

                                                                            8
 Putting green visual quality
                                 Scale 1-9, 9=best putting green quality




                                                                            7

                                                                            6

                                                                            5

                                                                            4

                                                                            3
                                                                                         SCALPING LEVEL TREATMENTS, applied 9-29-97                                                                                                                                   Dirt
                                                                            2                       (averaged over chemical and seed rate treatments)                                                                                                                 Stubble
                                                                            1

                                                                            9

                                                                            8
  Putting green visual quality
                                  Scale 1-9, 9=best putting green quality




                                                                            7

                                                                            6

                                                                            5

                                                                            4

                                                                            3
                                                                                                                                                                                                                                 25 lb rye /10 lb poa
                                                                                              SEED RATE TREATMENTS, applied 10/10/97
                                                                            2                                                                                                                                                    40 lb rye /10 lb poa
                                                                                                  (averaged over chemical and scalping level treatments)
                                                                            1
                                                                                                                                       09-Jan
                                                                                                                                                21-Jan
                                                                                                                                                         02-Feb
                                                                                                                                                                  14-Feb
                                                                                                                                                                           26-Feb




                                                                                                                                                                                                                                                    02-Jun
                                                                                                                                                                                                                                                             14-Jun
                                                                                                                                                                                                                                                                      26-Jun
                                                                                                            04-Dec
                                                                                                                     16-Dec
                                                                                                                              28-Dec




                                                                                                                                                                                    10-Mar
                                                                                                                                                                                             22-Mar
                                                                                                                                                                                                      03-Apr
                                                                                                                                                                                                               15-Apr
                                                                                                                                                                                                                        27-Apr
                                                                                                                                                                                                                                  09-May
                                                                                                                                                                                                                                           21-May
                                                                                29-Oct




                                                                                                                                                                                                                                                                               08-Jul
                                                                                                                                                                                                                                                                                        20-Jul
                                                                                         10-Nov
                                                                                                   22-Nov




                                                                                                                                                                  Date (1997-1998)


*, **, *** Significant at P ≤ 0.05, 0.01, and 0.001, respectively.
                                                                                                                                                                               17
Highest monthly air temperatures on-site at Desert Horizons Country Clubvs. 30-year average highest
monthly temperatures in Indio, CA.
                                      120
   Highest monthly temperature (ºF)




                                      110

                                      100

                                      90

                                      80

                                      70
                                                                                                                                                                                                  On-site
                                      60
                                                                                                                                                                                                  30-yr norm
                                      50
                                              Mar-97

                                                          Apr-97



                                                                                  Jun-97



                                                                                                        Aug-97

                                                                                                                   Sep-97

                                                                                                                              Oct-97
                                                                      May-97




                                                                                                                                                   Dec-97

                                                                                                                                                             Jan-98

                                                                                                                                                                       Feb-98

                                                                                                                                                                                Mar-98

                                                                                                                                                                                         Apr-98

                                                                                                                                                                                                  May-98

                                                                                                                                                                                                           Jun-98
                                                                                             Jul-97




                                                                                                                                                                                                                    Jul-98
                                                                                                                                         Nov-97


                                                                                                                                       Date




Lowest monthly air temperatures on-site at Desert Horizons Country Club Cvs. 30-year lowest highest
monthly temperatures in Indio, CA.
                                      80
   Lowest monthly temperature (ºF)




                                      70
                                      60
                                      50
                                      40
                                      30
                                      20
                                                                                                                                                                                                  On-site
                                      10                                                                                                                                                          30-yr norm
                                      0
                                           Mar-97

                                                       Apr-97



                                                                               Jun-97



                                                                                                      Aug-97

                                                                                                                 Sep-97

                                                                                                                            Oct-97
                                                                   May-97




                                                                                                                                                  Dec-97

                                                                                                                                                            Jan-98

                                                                                                                                                                      Feb-98

                                                                                                                                                                                Mar-98

                                                                                                                                                                                         Apr-98

                                                                                                                                                                                                  May-98

                                                                                                                                                                                                           Jun-98
                                                                                           Jul-97




                                                                                                                                                                                                                    Jul-98
                                                                                                                                        Nov-97




                                                                                                                                       Date




                                                                                                                                             18
Weekly mean warm (12 noon to 4 p.m.) and cool (2 a.m. to 6 a.m.) air temperatures on-site
at Desert Horizons Country Club, Indian Wells, CA and average percent bermudagrass
green coverage of all treatments from 2/20/97 to 8/02/97.

                       120                                                                                                                                                        100
                                               Warm                                                                                                                               90




                                                                                                                                                                                        % bermuda green coverage
                       110
                                               Cool                                                                                                                               80
                       100                     % Bermuda
    Temperature (ºF)




                                                                                                                                                                                  70
                       90                                                                                                                                                         60
                       80                                                                                                                                                         50
                       70                                                                                                                                                         40
                                                                                                                                                                                  30
                       60
                                                                                                                                                                                  20
                       50                                                                                                                                                         10
                       40                                                                                                                                                         0
                             15-Sep




                                                                                   19-Jan

                                                                                            09-Feb




                                                                                                                                                       15-Jun
                                                                 08-Dec

                                                                          29-Dec




                                                                                                          02-Mar

                                                                                                                   23-Mar

                                                                                                                            13-Apr

                                                                                                                                     04-May

                                                                                                                                              25-May
                                      06-Oct

                                               27-Oct




                                                                                                                                                                06-Jul

                                                                                                                                                                         27-Jul
                                                        17-Nov




                                                                                                 Date



Weekly mean warm (12 noon to 4 p.m.) and cool (2 a.m. to 6 a.m.) soil temperatures on-site
(2-inch depth) at Desert Horizons Country Club, Indian Wells, CA and average percent
bermudagrass green coverage of all treatments from 02/16/97 to 08/02/97.

                       120                                                                                                                                                        100
                                               Warm
                                                                                                                                                                                         % bermuda green coverage
                       110                                                                                                                                                        90
                                               Cool                                                                                                                               80
                       100
    Temperature (ºF)




                                               % Bermuda                                                                                                                          70
                       90                                                                                                                                                         60
                       80                                                                                                                                                         50
                       70                                                                                                                                                         40
                                                                                                                                                                                  30
                       60
                                                                                                                                                                                  20
                       50                                                                                                                                                         10
                       40                                                                                                                                                         0
                             15-Sep




                                                                                   19-Jan

                                                                                            09-Feb




                                                                                                                                                       15-Jun
                                                                 08-Dec

                                                                          29-Dec




                                                                                                          02-Mar

                                                                                                                   23-Mar

                                                                                                                            13-Apr

                                                                                                                                     04-May

                                                                                                                                              25-May
                                      06-Oct

                                               27-Oct




                                                                                                                                                                06-Jul

                                                                                                                                                                         27-Jul
                                                        17-Nov




                                                                                                 Date



                                                                                                     19
Weekly mean warm (12 noon to 4 p.m.) and cool (2 a.m. to 6 a.m.) air temperatures on-site
at Desert Horizons Country Club, Indian Wells, CA and average percent bermudagrass green
coverage of all treatments from 9/22/97 to 7/22/98.

                       120                                                                                                                                                      100
                                                                 Warm                                                                                                           90




                                                                                                                                                                                       % bermuda green coverage
                       110
                                                                 Cool                                                                                                           80
                       100
    Temperature (ºF)




                                                                 % Bermuda                                                                                                      70
                       90                                                                                                                                                       60
                       80                                                                                                                                                       50
                       70                                                                                                                                                       40
                                                                                                                                                                                30
                       60
                                                                                                                                                                                20
                       50                                                                                                                                                       10
                       40                                                                                                                                                       0
                             15-Sep




                                                                                     19-Jan

                                                                                              09-Feb




                                                                                                                                                     15-Jun
                                                                   08-Dec

                                                                            29-Dec




                                                                                                        02-Mar

                                                                                                                 23-Mar

                                                                                                                          13-Apr

                                                                                                                                   04-May

                                                                                                                                            25-May
                                      06-Oct

                                               27-Oct




                                                                                                                                                              06-Jul

                                                                                                                                                                       27-Jul
                                                        17-Nov




                                                                                                       Date



Weekly mean warm (12 noon to 4 p.m.) and cool (2 a.m. to 6 a.m.) soil temperatures on-site
(2-inch depth) at Desert Horizons Country Club, Indian Wells, CA and average percent
bermudagrass green coverage of all treatments from 9/22/97 to 7/22/98.

                       120                                                                                                                                                      100
                                                                 Warm
                                                                                                                                                                                      % bermuda green coverage
                       110                                                                                                                                                      90
                                                                 Cool                                                                                                           80
                       100
    Temperature (ºF)




                                                                 % Bermuda                                                                                                      70
                       90                                                                                                                                                       60
                       80                                                                                                                                                       50
                       70                                                                                                                                                       40
                                                                                                                                                                                30
                       60
                                                                                                                                                                                20
                       50                                                                                                                                                       10
                       40                                                                                                                                                       0
                             15-Sep




                                                                                     19-Jan

                                                                                              09-Feb




                                                                                                                                                     15-Jun
                                                                   08-Dec

                                                                            29-Dec




                                                                                                        02-Mar

                                                                                                                 23-Mar

                                                                                                                          13-Apr

                                                                                                                                   04-May

                                                                                                                                            25-May
                                      06-Oct

                                               27-Oct




                                                                                                                                                              06-Jul

                                                                                                                                                                       27-Jul
                                                        17-Nov




                                                                                                       Date



                                                                                                       20
         Air and Soil Temperatures at Different Phases of
      Bermudagrass Green-Up on Overseeded Putting Greens
                                               Season One                   Season Two
    INITIAL GREEN-UP                          Start    End                 Start    End
    Approximate dates:                      2/16/97      3/29/97         2/22/98     3/21/98
    % bermudagrass green coverage:            12.7         31.2            13.2        37.1
                                             Warm          Cool           Warm         Cool
    Average air temperature (ºF)z:           86.4          53.2            —            —
    Average soil temperature (ºF):           75.4          50.3            —            —

    LAG GREEN-UP                              Start        End             Start        End
    Approximate dates:                      3/29/97      5/10/97         3/21/98     5/23/98
    % bermudagrass green coverage:            33.7         33.1            35.9        40.1
                                             Warm          Cool           Warm         Cool
    Average air temperature (ºF):            86.1          59.3           79.7         55.3
    Average soil temperature (ºF):           82.0          58.9           89.4         68.4

    BERMUDA TRANSITION                        Start        End             Start        End
    Approximate dates:                      5/10/97      7/12/97         5/23/98     7/25/98
    % bermudagrass green coverage:            45.8         88.8            53.3        94.9
                                             Warm          Cool           Warm         Cool
    Average air temperature (ºF):            98.3          69.8           94.2         68.2
    Average soil temperature (ºF):           91.9          70.2           96.8         74.2

z
 Temperatures are the average of the daily warm (12 noon to 4 p.m.) or cool (2 a.m. to 6 a.m.)
temperatures for the time period specified.



                                               21
   Summary: Fall-Applied Treatment Effects on the Spring
       Transition of Bermudagrass Putting Greens

1. During two consecutive years, fall-applied treatments associated
with the renovation and overseeding of a Tifgreen putting green nursery
did not affect the amount of bermudagrass green coverage in the
following spring and summer.

2. During the second year, these treatments also did not affect the
visual turfgrass quality for an overseeed bermudagrass putting green.

3. One probable explanation why the treatments were not significant
is that fall and winter temperatures were relatively mild, resulting in
little if any freezing plant stress to act as a synergist with plant stress
related to renovation and overseeding treatments. Actually, fall and
winters are relatively mild in the Coachella Valley.

4. Under the conditions of this study, poa trivialis, was the dominant
component of the mature overseeding and it persisted for a longer time
during the summer than perennial ryegrass.




                                    22
  Summary: The Influence of Air and Soil Temperatures on
   the Spring Transition of a Bermudagrass Putting Green

Based on the two seasons of data from this study, the following
observations can be made:

1. Initial bermudagrass green-up occurred in mid to late February
when warm (12 noon to 4 p.m.) air temperatures were in the 80's (ºF).

2. Bermudagrass transition initiated during mid to late May and
completed mid to late July. During this period, cool (2 a.m. to 6 a.m.)
soil temperatures were in the 70ºF range.


     Summary: Can Information Concerning the Spring
  Transition of Bermudagrass Putting Greens Also Apply to
     the Spring Transition of Bermudagrass Fairways?

1. It would not be unexpected to find that the growth response of
common bermudagrass to air and soil temperatures during the spring
and summer is similar to the growth response of hybrid bermudagrass.

2. However, it would not be surprising to learn that the spring
transition of a common bermudagrass fairway, overseeded with
perennial ryegrass, has a different rate than a hybrid bermudagrass
putting green basically overseeded with poa trivialis.



                                  23

				
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