Going for the Gold withBermudagrass Greens: Part IIWhile the basics remain the same, tools have become available tohelp "fine-tune" the conditioning of bermudagrass putting surfaces.

by JOHN H. FOY

A faster rate of organic matter accumulation is a concern with the ultradwarfs. If not properly managed starting at establishment, aproblem can quickly develop. The accumulation in this photo developed in a little over six months.

GOING FOR THE GOLD withbermudagrass greens is cer-tainly achievable today. Over

the past several years, further refine-ments in management programs andnew techniques such as growth regu-lator treatments have become available~These updated management strategieshave made it possible to provide a levelof quality more in keeping with cur-rent demands and e?Cpectations. Withproper resources and good manage-ment, outstanding playing surfaces forregular and championship play can beprovided with bermudagrass greens.

New bermudagrass cultivars called"ultradwarfs" are also available now.These new bermudagrasses are furtherraising the standards of putting greenquality on golf courses throughout thehot, humid regions of the country.

Updated Management Strategiesfor Bermudagrass Greens

Spoon feeding fertilization: Relativeto other turfgrasses, the bermuda-grasses have a higher fertilization re-quirement to produce and maintain adense, green turf cover. The rule ofthumb with Tifdwarf and Tifgreen putt-ing surfaces has been to supply lIb. ofactual nitrogen per 1,000 sq. ft. permonth during the growing season.While not fully supported by universityresearch, the practice of nitrogen topotassium fertilization ratios in the 1:1to even 1:2 range has also been foundto produce the best results at mostcourses. To supply this amount ofnutrients, applications of granularfertilizers on a schedule of every 2 to 4weeks has been the standard regime for

many years. Yet at times, difficultieshave been encountered in trying tomaintain a constant shoot growth rateand consistent playability.

Spoon feeding, generally consistingof spray applications of low rates ofreadily available nutrients on a frequentbasis, has been a common practice withcool-season turfgrass putting greensfor many years. With bermudagrassputting greens in Florida, it took thepersistence of an abnormal and adverseweather pattern to produce a change infertilization practices. With the onsetof the EI Nino weather pattern and aprolonged period of excessive rain, itwas difficult to follow standard feitili-zation programs. Besides not being ableto apply and water-in granular fertilizermaterials, fertigation was not an optioneither because supplemental irrigation

NOVEMBER/DECEMBER 2000 1

At a growing number of courses around the state of Florida, conversion to one ofthe new ultradwarf bermuda cultivars has or will be made in the next few years.

was not needed. Thus, out of sheerdesperation, spray application fertili-zation programs were undertaken atcourses around Florida. It was quicklyrealized that spoon-feeding was aviable strategy for maintaining ber-mudagrass greens.

Along with being able to manageshoot growth rates more effectively,another positive aspect of spoon-feed-ing is that total annual fertilizationrates have been reduced. At a fewcourses, spoon-feeding programs arebeing practiced exclusive of all othermethods. However, some concerns doexist about being able to supply andmaintain adequate nutrient availabilitywith this approach and in turn sustain-ing uniform growth. A more commonand, in my opinion, safer strategy is tomaintain a nutrient base with once-a-month applications of a complete typegranular fertilizer that contains a slow-release nitrogen source. It is suggestedto supply O.5lbs. of actual nitrogen per1,000 sq. ft. with each application.Then, in between and on an every-5-to-10-days schedule, spoon feed 0.1 to0.25 lbs. of nitrogen per 1,000 sq. ft.per application. Regular soil and tissuenutrient testing should be performedto ensure that adequate and balancednutrition levels are maintained.

Double cutting and rolling: WithTifdwarf, and even more so with Tif-green putting greens, there are timeswhen an elevated height of cut mustbe maintained to ensure turf survival.

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In Florida during the summer rainyseason, sunlight intensity is reduceddue to the persistence of overcast skies.The bermudagrasses have a high sun-light requirement, and just a few daysof heavily overcast weather can nega-tively impact health and quality. If aheight of cut of 132"or less is beingmaintained, turf density and healthbegin to decline and rapid invasion ofalgae can be expected. Double cuttingand/or rolling are practices that cancompensate for a higher height of cutand continue to provide a smooth ballroll and medium to fast putting speed.

In the past, double cutting and/orrolling of putting surfaces were prac-tices that were reserved for tourna-ments or special events. However, in aneffort to accommodate golfer demandsfor fast to very fast putting speeds, thesepractices are being conducted on aroutine basis at more and more courses.At one club in Naples, Florida, doublecutting the greens is typically performedmore than 200 days a year. Obviously,this consumes a significant number ofadditional manpower hours and re-duces the life expectancy of the mow-ing units. More time also is required tocomplete course preparations eachmorning. The members, however, arevery supportive and accept the addi-tional cost incurred because they areprovided with top quality putting greenconditioning.

During the early to mid-1990s, roll-ing of putting surfaces increased in

popularity. In addition to increasingputting speeds, this practice producesa marked improvement in surfacesmoothness with bermudagrass greens.A concern with rolling putting greens,however, was the increase of soil com-paction and its effect on turf health overthe long term. In a study conducted atNorth Carolina State University, it wasfound that no change in compactionoccurred with high-sand-contentUSGA-type rootzone mixes, evenwhen daily rolling was conducted for70 consecutive days.2

It has been my experience that thebest results are achieved when ber-mudagrass greens are rolled two to fourtimes per week. Care does need to beexercised when the turf is not activelygrowing or is under stress because ofthe excessive wear that can occuraround the perimeters of the puttingsurfaces.

Topdressing: Sand topdressing ofputting surfaces is a basic managementpractice that goes back to the linkscourses of Scotland. Along with hav-ing an important role in rootzonemanagement, topdressing produces asmoother, more consistent surface andfaster putting speeds. In applying top-dressing, the rule of thumb is to try tomatch the frequency and amount ofmaterial with the growth rate of theturf. During the summertime, whenactive bermudagrass growth is occur-ring, topdressing every two to fourweeks has been the standard regimeused at most courses. However, be-cause of equipment limitations it wasdifficult to accomplish light applica-tions in a timely and efficient manner.Along with inconveniencing golfers, afew days were required for the sand towork down into the turf canopy and fora good playing surface to redevelop.

Improvements in application equip-ment have been made so that very lightdustings of sand can be made and allthe greens topdressed in a few hours.With these light applications, brushingor even overhead irrigation can be per-formed to work the sand down intothe turf so that most golfers can't tellthat a topdressing has been performed.Furthermore, the use of dry materialfacilitates application and incorpora-tion into the turf. At the courses wherepremium quality conditioning is beingmaintained, the putting surfaces aredusted on a 5-to-IO-day schedule. Withmore frequent topdressing, however,extra attention must be given to main-tenance of the mowing units to keepthem in precise operating condition.

Check the temperature of bermudagrass sprigs. If excessive temperatures build upin shipment, sprig viability and turf establishment will be affected.

Growth regulator treatments: Uni-form turf growth is needed to ensurethe persistence of good coverage andrecovery from traffic and wear damage.Excessive shoot growth rates, however,negatively affect playability and, in par-ticular, reduce putting speeds. Thatchaccumulation also is a concern withhigh growth rates. As mentionedearlier, spoon feeding fertilization pro-grams can help manage the growth rateof bermuda putting surfaces. However,during the summer months, difficultieswith rapid growth and inconsistentconditioning can occur. Especiallyduring the mid to late afternoon, anoticeable decline in putting speedscan be a problem. Conducting a secondmidday mowing of putting greens is notan option, nor is it a practical solutionat most courses.

In the early 1990s, the turfgrassgrowth regulator trinexapac-ethyl(Primo) rapidly gained popularity as amanagement tool for bermudagrassfairways and tee surfaces. Monthlytreatments slowed down shoot growthrates, mowing frequency was reduced,and there were less turf scalping andclipping accumulation problems. Addi-tional benefits of the trinexapac-ethyltreatment program are increased den-sity and a darker green color with re-duced fertilization. The use of a growthregulator on bermudagrass fairwayshas become widely accepted and isnow a standard practice at coursesthroughout Florida.

When discussions about using agrowth regulator on bermudagrassputting surfaces first started, I had anumber of reservations about thispractice. However, testing of low-rateapplications was undertaken and it wasfound that more consistent and fasterputting speeds could be maintained atthe same or even a slightly higherheight of cut. A "dwarfing" effect alsooccurs, such that turf density is in-creased. Trinexapac-ethyl treatmentsalso help mask off-type surface con-tamination. In 1996, a label revisionwas made that allows use of this growthregulator on Tifdwarf and Tifgreengreens.3 As with fairways, treatmentof bermuda putting surfaces withgrowth regulators has become a widelyaccepted practice. At the vast majorityof courses in Florida, treatments arebeing conducted on a regular basisthroughout the growing season and noadverse side effects have been noted.The ability to effectively manage growthhas had a significant positive impact onbeing able to produce and maintain

consistent conditioning of bermuda-grass putting surfaces.

Experiences with the UltradwarfBermudagrass CuItivars

There is simply no way around thefact that over the past 10 to 15 years,golfer expectations and demands haverisen dramatically. Even with theknowledge and management toolsavailable today, meeting these demandswith Tifgreen bermudagrass greens is

an almost impossible challenge. Tif-dwarf is also being pushed to its limits.Furthermore, while a degree of successhas been achieved in maintainingbentgrass putting greens in hot, humidregions, it is not an environmentallyand economically sound approach.Thus, there is lots of interest in newbermudagrass cultivars that have im-proved performance characteristicsand are better adapted for meetingcurrent demands.

Since the 1980s and continuingthrough the 1990s, efforts have beenunderway by turfgrass breeders, pro-ducers, and golf course superinten-dents to develop or select improvedbermudagrasses for putting greens. Thisresulted in the introduction of newcultivars that are now being commonlyreferred to as ultradwarfs. While thereare genetic and morphological differ-

ences between the cultivars, all theultradwarfs have a higher shoot densityand finer leaf blade relative to Tifdwarf.They also have exhibited excellenttolerance to a ~" height of cut forextended periods of time. At a. fewcourses, heights of cut of Y1.o" or evenless are being maintained. The im-proved performance characteristics ofthe ultradwarfs make it possible toprovide an extremely smooth ball rolland, when desired, fast to very fastputting speeds. Although additional

time is needed for thorough evaluationof these new cultivars, generally it isagreed that one or more of them willreplace Tifdwarf as the standard onputting greens in hot, humid regions.

Champion, FloraDwarf, and Tif-Eagle are the commercially availableultradwarfs, and the cultivar MiniVerdewas released recently. In 1997, the firstfull set of ultra dwarf (Champion) putt-ing greens was established in Florida onthe Cypress Course at Bonita Bay Eastin Bonita Springs. Since then, ultra-dwarfs have been used for replanting oron new greens at nearly 100 coursesaround the state. No doubt this numberwill increase rapidly over the next fewyears, given the number of courseswhere replanting is needed to addresssurface contamination problems andwith new construction continuing at afast pace.

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Concerning management of ultra-dwarf putting surfaces, they still are allbermudagrasses and, as such, a lot ofthe basics are similar to what is requiredto produce and maintain premiumquality conditioning with Tifdwarf. Yet,there are also some differences thathave been identified. The following isa summary of experiences with manag-ing ultra dwarf greens at several coursesaround Florida over the past two tothree years.

Planting and establishment: Thehybrid bermudas do not produce viableseed and thus must be established viavegetative means. Sprigging has beenand continues to be the standard plant-ing process~ While there is some debateover the exact size of a bushel, spriggingrates in the range of 20-30 bushels per1,000 sq. ft. typically have been usedwith the ultradwarfs. At a few courses,however, it was observed that theestablishment of full turf coverage wasslowed down significantly with a lowsprigging rate. It is being recommendedwith TifEagle that sufficient materialbe uniformly spread over the soilsurface so that there are no open voidsgreater than 3" .This is a good guidelinesince sprigging rates can be subjective,and after being mechanically cut in, itis very difficult to gauge the actualamount of material used. Full turfcoverage can be established in as littleas six to eight weeks with the ultra-dwarfs.

A major difference that has beennoted with the grow-in of ultra dwarfgreens is the need to start mowing at asignificantly lower height of cut. Aswith Tifdwarf, mowing the greens isinitiated 10 to 14 days after sprigging.However, instead of starting out atabout %", the mowers need to be setup in the range of %2" to 116". Then theheight of cut needs to be lowered pro-gressively to ~" and maintained at thisheight through the grow-in process. Forquite a few people, this has taken somegetting used to. Furthermore, the ultra-dwarfs need and respond to frequentverticutting, spiking, and topdressingduring grow-in.

Thatch/biomass management: Aconcern that was identified early onwith the ultradwarfs was their fasterrate of thatch/biomass accumulationrelative to Tifdwarf. While there issome debate over terminology, it is stilla fact that the ultradwarfs can producea distinct and significant organic matlayer between the turf surface androotzone mix. The bottom line is thatthis is an important management con-

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sideration, and from the start, programsneed to be geared to not allowing anexcessive organic matter accumulationto develop. Prevention is the key toensuring long-term successful resultswith the ultradwarfs.

Based on experiences at a numberof courses and on university research,nitrogen fertilization has a very impor-tant role in the management of thatch/biomass accumulation and turf quality.sWhile certainly not a new concept inturfgrass and putting green manage-ment, it has taken a little bit of timeto determine the best programs formaintaining good turf quality withoutcausing excessive growth and organicmatter accumulation. At this time, aprogram of supplying 0.5 to 1.0 lb. ofactual nitrogen per 1,000 sq. ft. permonth during the growing season issuggested. The frequency of applica-tions is as important as the amount ofnitrogen being supplied. Spoon feedingprograms are the standard approachbeing used at the vast majority ofcourses with ultradwarf putting sur-faces. While granular fertilizer applica-tions also are being made, the verydense turf cover of the ultra dwarfscan cause problems with getting thematerials down into the canopy. This istrue even with mini- or micro-blendformulations. As far as the other macro-and micronutrients are concerned,ultra dwarf requirements appear to befairly consistent with those of Tifdwarf.An increased incidence of leaf spot dis-ease activity has been observed on Tif-Eagle putting surfaces when adequatepotassium levels are not maintained.

Along with careful nitrogen fertili-zation, frequent and light verticutting/grooming and topdressing are neededwith the ultradwarfs to maintain opti-mum turf quality and prevent excessiveorganic matter accumulation. Duringthe growing season, these practicesneed to be conducted on a weeklybasis. Unlike Tifdwarf, severe verticut-ting or excessive topdressing rates canbe very detrimental to the ultradwarfs.As with granular fertilizer applications,some difficulties have also been en-countered with incorporation of top-dressing sand due to the very densecanopy of the ultradwarfs. Light verti-cutting or use of groomer attachmentsto open up the turf canopy prior totopdressing is a common and success-ful strategy being used at a number ofcourses. Another option that is gain-ing popularity is using rotary fertilizerspreaders to apply dried and baggedtopdressing sand. This approach allows

very light applications in an efficientand timely manner.

With astute fertilization and adher-ence to good topdressing and verticut-ting regimes, thatch/biomass accumu-lation with the ultra dwarfs can bemanaged effectively. Thus, additionalcoring, relative to what is routinelydone with Tifdwarf putting surfaces,has not been required. In the Centraland South Florida areas, three coringoperations during the growing seasonwith 'li" diameter or larger tines hasbeen adequate for management ofrootzone physical characteristics. Aswith Tifdwarf greens, however, caredoes need to be exercised during latesummer and early fall with mechanicaloperations. During this time, intenseenvironmental stress also occurs andrecovery from damage is delayed. Fur-thermore, as with Tifdwarf greens,periodic water injection cultivation(WIC) or small-diameter aerification isvery beneficial and encouraged.

Other considerations: In this articleit will not be possible to cover in detailevery aspect of managing ultra dwarfbermudagrass putting surfaces. In fact,we are still in the learning process withthese new cultivars. There are a fewother management factors to consider,though.

First, it is well established that ber-mudagrass has very poor shade toler-ance. Early on with the ultradwarfs,it was speculated that their increasedshoot density and finer leaf bladewould provide a degree of shade toler-ance. This has turned out not to be thecase. At several courses that have con-verted to one of the ultradwarfs, prob-lems have been experienced with main-taining a dense, good quality turf inall the same areas where shade was aproblem before. Full sunlight exposure,all day long, is an absolutely essentialingredient in maintaining top qualitybermudagrass putting surfaces. This istrue regardless of the cultivar. Further-more, the ultra dwarfs also are nega-tively impacted when sunlight intensityis reduced by heavy overcast condi-tions. Maintaining a slightly higherheight of cut during the rainy season isadvisable, but on the positive side, it isstill possible to provide a good qualityplaying surface.

Next, the ultradwarf cultivars Cham-pion, MiniVerde, and TifEagle all pos-sess improved cool-temperature colorretention and growth relative to Tif-dwarf. Thus, for courses in South andeven Central Florida, the need forwinter overseeding is further reduced.

More frequent light topdressing is another means of providing a smooth, true ball rolland medium to fast putting speeds.

When cold nighttime temperatures dooccur, some loss of green color results.However, with the return of mildertemperatures, it is possible to producea rapid greenup response. By nothaving to overseed, golfers do nothave to put up with the disruptionsand inconvenience of the fall establish-ment and spring transition operations.

For North Florida and the Southeast,a period of winter dormancy will stilloccur, and at facilities where moderateto heavy play is hosted during this time,interseeding/overseeding programs willstill be necessary. The increased densityof the ultradwarfs has been perceivedas an obstacle to oversee ding establish-ment, but successful results have beenachieved at a number of courses. It alsoshould be pointed out that at a coupleof courses, satisfactory results havebeen experienced by not overseeding,but covering the putting surfaces dur-

ing times when freezing temperaturesare expected.

Finally, an additional attribute thathas been noted with the ultradwarfs isincreased resistance to fairway/roughbermuda encroachment. Encroach-ment of coarse-textured bermudagrassinto the perimeters of Tifgreen andTifdwarf putting surfaces is an age-oldproblem that results in a progressiveloss of usable surface area. With thecombination of increased density andbeing maintained at lower heights ofcut, at least so far, encroachment prob-lems have not been experienced onultra dwarf greens.

As to the life expectancy of ultra-dwarf putting surfaces, only time willtell. Yet, it is reasonable to expect themto at least be equal to the 10- to 20-year life of Tifdwarf putting surfaces.With more control and emphasis beingplaced on production quality control

and turfgrass certification, we hope itwill also be possible to avoid or reducethe contamination problems that haveplagued bermudagrass courses in thepast.

SummaryMaintaining extremely fast putting

speeds at all courses with bermudagrassgreens is not being encouraged or con-doned. Yet, the standards of condition-ing and quality have been raised andthe benchmark continues to be set bybentgrass greens. For southern golfcourses with bermudagrass greens, pro-viding comparable conditioning hasalways been a challenge. With theknowledge and tools available today,however, it is possible to maintain asmooth, true ball roll and a consistentputting speed throughout the course.As discussed in this article, there arepractices that can be used to producefaster putting speeds if there is a com-mitment to providing the necessaryresources.

Furthermore, while it is still early inthe game, the new ultradwarfbermudasare providing a more level playing fieldfor southern golf courses. At thecourses where they have been used, thegolfers have been pleased with theimproved playing surfaces. It should bestressed that the ultra dwarfs do requireintensive management and thus maynot be suited for all courses. There isstill not a perfect grass, but at courseswhere premium quality putting greenconditioning is expected or demanded,the ultra dwarf bermudas are an optionthat merits strong consideration.

Literature Cited:1Foy, John H. (1991). Going for the Goldwith Bermudagrass Greens. USGA GreenSection Record. Vol. 29, No.4, pp. 1-4.2Hartwiger, Chris (1986). The Ups andDowns of Rolling Putting Greens. USGAGreen Section Record. Vol. 34, No.4, pp. 1-4.3DiPaola, Joe & Shepard, Dennis (2000).Regulate Growth and Improve Turf Qual-ity. Golf Course Management. March,2000, pp. 56-59.4Elsner, Earl & McWhorter, Doug (1999).Bermudagrass Sprig Heat Tolerance.USGA Green Section Record. Vol. 37, No.5, pp. 7-9.SWhite, Richard (1999). Unleash the FullPotential of New Bermudagrass Culti-vars. USGA Green Section Record. Vol. 37,No.5, pp. 16-18.

JOHN FOY is Director of the USGA GreenSection's Florida Region, where he visitsgolf courses throughout the state of Florida.

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