The residual effect of rolling on green speed is not always clear cut. Several research studies report a measurable residual effect up to 48 hours after rolling,while others report the increase lasts not more than one day.

Research You Can L]se

More Light onLightweight RollingResearch is shedding light on rollingas a season-long maintenance practice.BY THOMAS A. NIKOLAI

In1901 Walter Travis wrote, "FromMay until October each greenshould be rolled daily with a light

roller, rather than once or twice a weekwith a heavy one."ll For the nextquarter century the debate over rollerfrequency and weight was waged innumerous publications. Before the issuewas resolved, however, most turf grassmanagers lost interest in rolling puttinggreens as the effects of soil compactionon turfgrass rooting became clearer. 2

In the early 1990s, the practice ofrolling greens was reinitiated due to the

JANUARY-FEBRUARY 2002 9

demand for faster green speeds.4 Withits resurrection came articles praising itfor tournament preparation whilewarning of negative effects if overusedfor regular play. Golf course superin-tendents searched for advice aboutroller use, but found little research re-garding rolling. Specifically, informationwas needed concerning the use ofrollers in a season-long program.1

Recognizing this need, a handful ofturfgrass researchers initiated studies oflightweight green rolling.

Researchers at Michigan State Uni-versity (MSU) rolled USGA and nativesoil bentgrass greens three times perweek. However, those treatmentsresulted in no significant change in turfquality, soil compaction, or water infil-tration from unrolled putting greenplots.7 At North Carolina State Univer-sity, bentgrass greens were rolled zero,one four, and seven times per week.Once again, plots rolled once per weekresulted in no reduction in turf grassquality.

and seven times per week were notimmediate. The reduction in turfgrassquality at those frequencies took threeto four weeks to become apparent.

GREEN SPEEDANDGOLFER PERCEPTIONMost rolling studies have considered theimmediate and residual effects that roll-ing has on green speed. All studies con-cluded that rolling noticeably increasesgreen speed on the day rolling isapplied. The amount of increase varied

One side observation was that rolling impacted dollar spot symptoms on the turf plots. The plot onthe right was rolled three times per week and showed few dollar spot lesions, while the left plot wasnot rolled and was heavily impacted by the disease.

FREQUENCY ANDCOMPACTIONOver the past decade three studies con-sidered the impact of season-long greenrolling on soil compaction. Penn StateUniversity researchers compared plotshaving both USGA-recommendedsand or native soil rootzones. Plots wererolled once or twice per week, but nochanges in turfgrass quality, soil bulkdensity, or water infiltration were foundin rolled plots versus plots that were notrolled. 3

10 GFtEEN SECTION FtECOFtD

Rolling four and seven times perweek decreased turfgrass quality onplots growing on both USGA-recom-mended sand rootzones and plots hav-ing native soil rootzones.4 Furthermore,compaction increased on the native soilgreens rolled four and seven times perweek during the first year of the study.It is noteworthy that the loss in qualityattributed to lightweight rolling four

from day to day, but rolled plots weregenerally one foot faster than non-rolled plots on the day they were rolled.

The residual effect that rolling has ongreen speed is not as clear-cut. Severalstudies report a measurable residualeffect up to 48 hours after rolling, whileother studies report the increase lastsnot more than one day. Some of theapparent discrepancy may be due to the

- -- ------------------'--"""'"-- -------------

Effect of rolling on Dollar Spot 1996

10

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Research plots at Michigan State University were rolled over a five-year period to study the effects ofthis maintenance practice when used in a season-long program.

L

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I = 0I Z 14-Jun 24-Jun.' 7-Aug 22-Augt. *, ** Significant at 0.05 and 0.01 probability lev~ls, respectively.

way the data are reported. Althoughstudies reported a statistically significantincrease in green speed up to 48 hoursafter rolling, the residual increases areusually three inches or less.9 Golfer sur-veys indicate that most golfers cannotdetect differences in green speed of sixinches or less.s Thus, the three-inchdifference is valid scientific reporting,but from a real-world aspect the greenswould not be noticeably faster to thegolfer two days after rolling.

The fact that most golfers cannotdetect differences in green speed of sixinches or less adds credence to theargument that posting green speedsmay be more bother than it's worth.Often, golfers argue over half-foot dif-ferences in green speeds, while surveysshow that even low handicappers can-not detect differences in green speedsthat accurately.

ROLLER WEIGHT AND TYPERoller weight and type appear to belinked together. It would seem logicalthat heavier rolling machines wouldresult in greater increases in green speedfor a longer period of time. However,.results from a Michigan State Univer-sity study indicate roller type must beconsidered in an evaluation of the effectof roller weight.

In the MSU study, a triplex attach-ment roller (single roller per attach-ment) weighing approximately 1,300pounds and a sidewinder roller (threerollers traversing the same area) weigh-ing about 950 pounds were included inthe study. Both increased green speedapproximately one foot on the day theywere applied compared to non-rolledplots. The day after rolling, however, thetriplex-rolled plots averaged threeinches faster than the non-rolled checkplot, while the sidewinder-rolled plotsaveraged six inches faster than thecheck.7

ROLLlNGYERSUS MOWINGRolling frequency and duration (lengthof time using the same roller schedule)have an effect on residual green speed,

too. This is most apparent when com-paring mowing height green speedstudies performed at the University ofArizona and again at Michigan StateUniversity. Both universities investi-gated whether it may be possible toraise mowing height and still retainputting speeds by incorporating rollingas a routine maintenance practice.

The two studies differed slightly inthat the roller frequencies differed, butthe difference in mowing heights wasidentical (0.03 inch).The University ofArizona study rolled two times perweek, while the MSU study rolledthree times per week. In the Universityof Arizona study, rolling was not aseffective in increasing green speed aslower mowing. In other words, thenon-rolled, low-cut turf was still fasterthan the rolled, higher-cut bentgrass.6

In the Michigan State study, the non-rolled, low-cut turf plots also wereinitially faster than the rolled high-cutplots. However, after two weeks ofrolling, the higher-cut plots retained thesame green speed as the non-rolled,low-cut turf on the day the greens wererolled and the day after rollingtreatments were applied.7

ROLLING ANDPEST OUTBREAKSGolf course superintendents have beenjustifiably concerned that rolling maylead to diseased turf. Dollar spot is aturfgrass disease that can be spread bymaintenance equipment that carriesfungal mycelium and infected planttissue from green to green. 10 Because ofthis, it may be reasonable to assume thatrolling would increase the severity ofthis disease. However, dollar spotseverity decreased on research greens atMichigan State University that wererolled three times per week for fivestraight years.

These positive results were obtainedbecause of the timing of the mowingand rolling. Similarly to most golfcourses, the research greens weremowed at dawn and rolled within anhour after mowing. This timing isbelieved to be important because earlymorning mowing may exacerbate therelease of guttation droplets forming atthe tips of the cut leaf blades. Theseguttation droplets are used as a nutrientsupply by fungal pathogens. Rollingwithin an hour after an early morningmowing may disperse concentrated

JANUARY-FEBRUARY 2002 II

guttation water, thus reducing thepathogen's ability to infect other plants.

Rolling also may affect the ability ofturfgrass insects to infect and populatean area. In 1998, Dr. Dan Potter fromthe University of Kentucky reportedthat black cutworm moths lay nearly alltheir eggs on the tips of leaf blades andthat many eggs survive passage throughthe mower blades and will later hatch.8

On a green rolling research site atMSU, bird activity highly coincidedwith numerous black cutworms beingobserved on the site.Whileno attempt wasmade toquantify thenumberof

cutwormson the site,significantly lessbird activity wasobserved on greens that wererolled.7 Considering debris adheres togreen rollers and is transported to thewash pad, it is conceivable that rollingcould have decreased the amount ofcutworms per green by removing eggswith the excess debris.

CONCLUSIONSAlthough the effect of roller weight isdependent on the type of roller used,results indicate it is safe to operate asidewinder roller (with three rollers)

12 GREEN SECTION RECORD

weighing up to 960 pounds three timesper week in a season-long program.Triplex attachment rollers can weighmore because there is less weight beingapplied on each roller. However, itis important that when a specific rollingprogram is adopted, the total number ofrounds and other factors impartingstress on the greens be kept in mind.

Research also suggests that rollingthree times per week increases greenspeed significantly, and the increase inspeed is still apparent up to six days

after rolling. This fre-quency may also

allow thesupenn-

tendentthe

flexibilityof raising the

cutting heightup to 0.03 inch

during the heat of summerand retain the same green speeds as thenon-rolled shorter height of cut.

Although the MSU studies suggestthat rolling after an early morningmowing decreases dollar spot severityand may pick up excess turfgrass leaflitter, resulting in fewer black cutworms,further research is needed. If additionalresearch can corroborate these obser-vations, rolling greens may prove to bemore important than just being a meansto increase green speed.

ACKNOWLEDGMENTSThe author would like to thank GeorgeHamilton, Chris Hartwiger, and DavidKopec for their correspondence duringthe writing of this article and theUSGA for five years of funding greenrolling research at Michigan StateUniversity.

REFERENCES1 Beard,]. B. 1994.Turf rolling. Grounds

Maintenance 29(1): 44-52.

2 DiPaola,]. M., and C. R. Hartwiger. 1994.Green speed, rolling, and soil compaction.Golf Course Management 62(9):49-51,78.

3 Hamilton, G.W,Jr., nw Livingston, andA. E. Grover. 1994.The effects of lightweightrolling on putting greens. Science and Golf II,pp.425-430.

4 Hartwiger, C. 1996.The ups and downs ofrolling putting greens. USGA Green SectionRecord 34(4):1-4.

5 Karcher, n E., T A. Nikolai, and R. N.Calhoun. 2000. Green speed:What do golfersknow? Australian Tuifirass Management2(4):30-32.

6 Kopec, n M., J. Long, n Kerr, and].]. Gilbert.1997.Initial investigations of mowing heightand greens rolling on ball roll of Penncrosscreeping bentgrass. 1997Turfgrass andOrnamentals Research Summary, pp. 41-48.

7 Nikolai,TA., P. E. Rieke,]. N. Rogers III,B.E. Leach, and M. Smucker. 1997.Some prettycool things about lightweight green rolling.In: Proc. 67th Michigan Turfgrass Conf., vol.26, Lansing, Mich., 20-24, 1997.

8 Potter, n A. 1998.Destructive TurfgrassInsects: Biology, Diagnosis, and Control. AnnArbor Press, Chelsea, Mich.

9 Rieke, P. E.,TA. Nikolai, M.A. Smucker, P.Grow, and n Roth. 1995.Turfgrass soilmanagement research report -1995. In:Proc. 66th Michigan Turfgrass Conf., vol. 25,Lansing, Mich., 15-18,Jan. 1996.

10 Smiley,R.W 1983. Compendium of Turf-grass Diseases.American PhytopathologicalSociety. St. Paul, Minn.

11 Travis,W]. 1901.Practical Golf. Harper &Brothers, New York, N.Y

THOMAS A. NIKOLAI is the tuifgrassacademic specialist at Michigan StateUniversity. He has ten years if experience ona golf course and ten years if experience as atuifgrass research technician.