Grasses for OverseedingBermudagrass FairwaysResults of a national trial demonstrate the consistentimprovement of perennial ryegrass cultivars.BY KEVIN N. MORRIS

It'strue that Americans love greengrass - especially when playinggolf. Uniform green grass to a golf

course superintendent, manager, orowner is akin to a perfectly round, red,luscious summer tomato to a farmer -the product sells itself. However, pro-ducing that perfect grass surface orsummer tomato is far from easy andnot always attainable.

For much of the southern half of theUnited States, overseeding bermuda-grass fairways is a common practiceused by golf courses to produce thatbeautiful green product that so manygolfers desire, especially those escapingthe winter blues of northern climates.It's not surprising, then, that green grasson greens, tees, and fairways adds to acourse's bottom line by increasingrounds in winter. And overseeding does

more for a golf course than add beauty,as actively growing turf in winter ismore tolerant of cart traffic, divots, andweed invasion than brown, dormantbermudagrass.

For these reasons, millions of poundsof seed are bought and sown each fall ongolf courses in this region. Golf courseowners, managers, and superintendentsseek grasses that establish quickly, exhibitexceptional playability, are aestheticallypleasing, and require less input. Conse-quently, a research project was developedand jointly sponsored by the UnitedStates Golf Association (USGA), theGolf Course Superintendents Associ-ation of America (GCSAA), and theNational Turfgrass Evaluation Program(NTEP) to evaluate cultivars, blends,and mixtures for use in overseedingbermudagrass fairways.

HOW THE TRIALS WERECARRIED OUTTen golf courses were chosen to hostthe on-site overseeding trials (Table 1).Because overseeding grasses provide atemporary playing surface for fall,winter, and spring, and are reseededeach year, cultivars were seeded in twoconsecutive years (fall 1999 and fall2000). Since speed, ease, and uniformityof transition from bermudagrass to theoverseeded grass in fall and back tobermudagrass in spring is one of thebiggest concerns when overseeding,entries were seeded in exactly the samelocation on each course for each of thetwo years. This allowed researchers toidentify entries that persisted over time.

NTEP solicited entries for the trialfrom sponsoring companies. Trials wereconducted with named cultivars and

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commercially available blends or mix-tures. In addition, experimental entriesthat were to be commercialized in theimmediate future (i.e., before the end ofthe testing cycle) also were permitted.Various species used in overseeding,such as perennial ryegrass and Foatrivialis were allowed. This led to thesubmission of many perennial rye grassentries as single cultivars or blends, andalso single cultivars of Foa trivia lis aswell as mixtures of perennial rye grassand Foa trivialis. In addition, two culti-vars of intermediate ryegrass and oneannual ryegrass cultivar were includedin the trial.

Annual ryegrass offers the advantageof less heat tolerance than perennialryegrass and thus a quicker transition inspring back to bermudagrass. However,annual ryegrass does not have the darkergreen color and finer leaf texture ofperennial ryegrass. Intermediate rye-grasses are developed by crossing annualand perennial ryegrass, then selectingplants that have the best traits of bothspecies. Companies have worked todevelop intermediate ryegrasses thatprovide a smooth spring transition backto bermudagrass, but also with a finerleaf texture and darker green color.

Trials were established on active playsites where golfers hit fairway golf shotsandlor drove golf carts. Plots were care-fully seeded by hand or by using a dropspreader. Since seeding rates varywidely from one region to another,

each location was consulted concerningtypical oversee ding rates in their area.Consequently, three seeding rates forthe ryegrasses (300,450, and 600 lbs.per acre), two rates for Foa trivia lis (100and 200 Ibs. per acre), and two rates formixtures (250 and 400 lbs. per acre)were developed. The most appropriaterate for each grass type was thenassigned to the locations (Table 2).• The experimental plot size was large(5 ft. X 20 ft.), replicated three times.A large plot size allowed for a greaterdistribution of traffic and divoting.Host courses provided the daily main-tenance of the fairway site. An advisorycommittee consisting of representativesfrom GCSAA, USGA, NTEp, univer-sities, and the turfgrass seed industryrecommended establishment and main-tenance procedures.

The researcher at the cooperatinguniversity was responsible for datacollection. The following data werecollected from each trial site:• Percent establishment rate (4-6 weeksafter seeding).• Turfgrass quality (monthly duringwinter and 2-4 times per month duringthe spring and fall transition period).• Plot color, genetic color (twice -late falll early winter and spring).• Rate or speed of transition frombermudagrass to overseeded grass in fall(2-4 times per month during fall).• Rate or speed of transition fromoverseeded grass to bermudagrass in

spring (2-4 times per month duringspring).• Environmental stress, traffic, and divotdamage, disease and insect damage, andother data deemed appropriate andfeasible by the research cooperator.

RESULTS OFTHETRIAL

FALL 1999 - SPRING 2000DATA COLLECTIONThe 42 entries in this trial (Table 3)were seeded in September or Octoberat the ten golf course sites. Establish-ment was good; no problems were seenwith any entries. Data collected fromfall 1999 through spring 2000 were com-piled, statistically analyzed, and reported.These data can be found in NTEPReport No. 00-13 and on the NTEPWeb site (www:ntep.org/onsite/ost.htm).

Following are general observationsconcerning the trials in fall 1999 -spring 2000:• The Foa trivia lis varieties were gen-erally slower to establish and developinto a dense stand than the perennialryegrasses. They also exhibit a lightergreen color than the perennial rye-grasses. The slow establishment mayprohibit the use of straight Foa trivia lisfor overseeding of fairways .• The Charlottesville, Virginia, site did .little to thin the bermudagrass on thefairways before overseeding. Overall,this resulted in a poor stand of the trial.Overseeding procedures at the other

18 GREEN SECTION RECORD

courses did not seem to affect trialestablishment.• Overall, placement of the tests(physical location on the course) wasvery good, with most being placedbetween the tee and the first landingarea. Traffic distribution and divotingappeared uniform at the sites visited .The Orlando, Florida, test was plantedat their golf academy (teaching facility)and received very little cart or foottraffic.

• Transition from overseeding grass tobermudagrass started early in most sites,as winter was mild and early spring waswarm in many locations. However, acool, wet April in the eastern portion ofthe U.S. slowed the transition by aidingthe overseeding grasses.• Generally, entries were consistent intheir performance from one location toanother. Several of the perennial rye-grasses were excellent in fall and winterthrough early spring. Transition back to

bermudagrass varied by location. Webelieve this was mainly due to differingweather patterns between locations.• In general, the perennial ryegrassesprovided the highest quality turf. Theexception was the high performance ofthe Poa trivialis varieties and perennialryegrass/ Paa trivia lis mixtures at theFlorida and Virginia locations. TheFlorida site had a severe annual blue-grass (Paa annua) invasion, which mayhave been less noticeable in the Paa

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Species or Composition

perennialry.rassperennial ryegrassPoa trivialisperennial ryegrassperennial ryegrassPoo trivia/is40% Windstar, 35% Sonata, 25% jet perennial ryegrass blendintermediate ryegrassinterm~diate ryegrass85% Paragon perennial ryegrass, 15%Stardust Poo ~perennial ryeg~perennial ryegrassperennial ryegrass85% Brightstar II perennial ryegrass. IS%Winterplay Poa trivialisperennial ryegrass

'!, 85% Citation III perennial ryegrass. 15%Winterstar Poo triviolisPoD trivia/isannual ryegrassperennial ryegrassperennial ryegrassperennial ryegrass33% Cutter perennial ryegrass. 33% Sunshine per:ennial ryegrass. .

33% Transist intermediate ryegrass25% jR-151. 25% jR'~142,25% jR-128. 25% JI\-265 perennial ryegrass b1~nd 'perennial ryegrass34% Pennant' II.33% Panther, 33% Seville II perennial ryegrassperennial ryegrassPoa trivia/isperennial ryegrass

I 33% Elfkin,33% MP58. 33% MP88 perennial ryegrass blendperennial ryegrass .perennial rye,grass .40% Pearl. 30% Pageant II,30% EP57 perennial ryegrass'blend4O%,EP56, 30% Pearl; 30% Academy perennial ryegrass blend .40% EP57.30% EP56,30% Flash perennial ryegrass blendperennial ryegrassperennial ryegrass33%Top Hat, 33% R2.33% Gator.II perennial ryegraSs blendPoa trivia/is34% Imagine, 33% Ice, 33% Lynx perennial ryegrass blend40% Palmer IU,20% Prelude III.20% Phantom perennial ryegrass,

I5% Laser Poo trivia/is ."perennial ryegraSs ..... Ie'50% Palmer 111,25% Prelude III.25% Phantom perennial ,.yegrass blend

Table 3On-Site Testing of GraSses for Overseeding of Bermudagrass Fairways

Entries and Sponsors li•.

Name

A1lsportLS-DEtProamBarlenniumPirouetteBarivieraProfessional's SelectTransistPick HRA-97First CutBrightstar "Charger IICitation IIIBrightstar II+WinterplayChargerCitation III +WinterstarWinterplayAxcella (ABT--99-3.268)ParagonPST--3BK-99Fiesta 3Futura 2500

MED-007CapriLeaderboardSeville IISnowbirdMP58Prime'ElfkinMPIIIMountain View Seed Blend J ,Mountain View Seed Blend 2Mountain View' Seed Blend 3 •Essence .Top HatCebeco Blend ISabreTourstarMarvelgreen + Laser

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JULY-AUGUST 2004 19

trivia/is plots. With the minimal pre-plant preparation at the Virginia site, thePaa trivia/is, being smaller seeded, had aneasier time falling through the bermuda-grass canopy and thus germinatedbetter.• At most locations, there was nostatistical difference in overall turf grassquality between the top 25-30 entries(out of a total of 42 in the trial). Wehave seen this happen in past overseed-ing trials. This may reflect the unusualnature of over:seeding. If an entry is verystrong in the beginning and receiveshigh quality ratings, it may receive lowratings during spring transition as it hascompeted too heavily with the ber-mudagrass, thus holding back thebermudagrass. Grasses that start slowlyand receive low ratings initially oftenbecome stronger later and receivehigher ratings during transition.

A major concern of overseeding ishaving a smooth transition from over-seeding grass back to bermudagrass inspring. In the first-year data from mostlocations, the annual ryegrass and inter-mediate rye grass entries transitionedmore quickly (going from 75% to 25%plot coverage in 3-4 weeks) than theperennial ryegrasses. At the Arizona andMississippi locations, Paa trivia/is entriesand perennial ryegrass/ Paa trivia lis mix-tures transitioned faster than perennialryegrass. However, at the California andFlorida sites, the opposite was true. Andin South Carolina and Texas sites, Paatrivia/is, intermediate ryegrass, andperennial ryegrasses transitioned in asimilar fashion. Again, we believe thesedifferences are weather and environ-ment-related.

FALL 2000 - SPRING 2001DATA COLLECTIONThe 42 entries seeded in fall 1999 wereseeded again in September or October2000 at the ten golf course sites. Thesame physical locations on the golfcourses were used with the followingtwo exceptions. Tucson Country Clubdecided to cease overseeding its fair-ways, so another test location was

20 G R E ENS E C T ION R E COR 0

needed. The cooperator decided onthe Country Club of Green Valley, siteof the on-site bentgrass and bermuda-grass trials, for the second year's over-seeding trial. Another fairway at theAtlanta Athletic Club was used in 2000due to lack of uniformity at theprevious site.

A progress report containing 2000-2001 data and management informationon this project was compiled and distrib-uted in November 2001. This report canalso be found on the NTEP Web site athttp://www.ntep.org/onsite/ost.htm.Following is a summary of the resultsfrom 2000 to 2001.

Data collected by cooperators on falland spring transition, percent groundcover of each species, color and turf-grass quality varied considerably fromlocation to location, as it did during fall1999 to spring 2000. Following aresome observations concerning thesecond year of this trial:• At five locations, the perennial rye-grass entries or blends of perennial rye-grasses were the best performers. Often,there was little or no statistical differenceamong the perennial ryegrasses foroverall quality, fall and spring transition.Following are the locations where alarge number of perennial ryegrassentries finished in the top statisticalgrouping for overall turfgrass quality:

Palm Desert, California (26 entries)Duluth, Georgia (28 entries)Starkville, Mississippi (19 entries)Crescent, Missouri (33 entries)Green Valley,Arizona (15 entries)

• At the Myrtle Beach, South Carolina,and Garland, Texas, locations, there wasno statistical difference among any ofthe 42 entries for overall turfgrassquality.• Paa trivia lis entries as a group finishedat the bottom of the trials listed aboveand at the top of the trials in Orlando,Florida; Houston, Texas; and Charlottes-ville, Virginia. Mixtures of perennialryegrass and Paa trivia lis performedclose to the top in the above locationsand close to the bottom at all otherlocations.

• At almost all locations, Paa trivia/isentries established significantly moreslowly than the perennial ryegrasses,taking until 30-40 days after seeding toestablish the same percentage groundcover as the perennial ryegrasses. Atsome locations (i.e., Green Valley,Arizona; Duluth, Georgia; Starkville,Mississippi), Paa trivia/is disappearedvery quickly in spring, leaving a plotwith only 30-40% green bermudagrass.Conversely, at the Houston, Texas, andOrlando, Florida, sites, Paa trivia lisentries transitioned more slowly andsmoothly than the perennial ryegrasses.• The intermediate rye grass entriesgenerally had lower quality ratings thanthe perennial ryegrasses, and they tran-sitioned more quickly. The two entriesTransist and Pick HR A-97 differ intheir appearance and performance.Transist appears to have more annualryegrass characteristics, which gives it alighter green color and causes it totransition more quickly. Pick HR A-97is darker green and behaves more like aperennial than an annual. The oneannual ryegrass entry, Axcella, finishedin the bottom third of all entries atmost locations.

SUMMARYSince seeding rates and maintenancelevels differed from one location to thenext, data were not summarized andaveraged across all locations. However,we can make the following generalconclusions concerning this trial:• Many perennial ryegrasses performwell in overseeding, and often there isno statistical difference among theentries. We have seen this same trend inother overseeding trials.• Paa trivialis may be useful in over-seeding fairways, though its performancemay be inconsistent. It is slower toestablish than perennial ryegrass, and itseems that when Paa trivialis is weakeneddue to heat or disease, it disappearsquickly. This leaves insufficient greenbermudagrass for acceptable quality.However, if the goal is little or nophysical disturbance of the bermuda

grass prior to overseeding, the smallseed size of Poa trivia lis allows it to siftthrough the bermudagrass canopy tomake soil contact. The result is a betterstand of Poa trivia lis compared toperennial ryegrass.• Perennial rye grass and Poa trivia lismixtures generally do not perform aswell as perennial ryegrass or Poa trivia liscultivars. The addition of Poa trivialisgenerally results in lower quality ratings,except where the Poa trivialis entriesperform exceptionally well. The mix-ture may hasten transition somewhat,

Green Valley,Arizona, and Palm Desert,California, intensively scalped andverticut their bermudagrass prior tooverseeding. This is a standard practicein the Desert Southwest and is probablymore beneficial to the perennialryegrasses.• Intermediate ryegrasses may be usefulin fairway overseeding if the goal is anearlier transition. However, this will alsodepend on whether the grass is closerto being a perennial than an annual.• Transition from the overseeding grassto bermudagrass in spring is rarely

The lower the quality of overseedingin fall, the less overseeding present inspring, often leading to a better springtransition. Use of a weaker cultivar orspecies may make for a better springtransition. However, if heat andhumidity come early, these weakergrasses may leave sooner than expected.

Overseeding bermudagrass fairwayshas definite benefits but also associatedrisks. An overseeding grass that is toostrong through the winter may lead toslower bermudagrass recovery in spring .Also, weather patterns can be quite

The National Turfgrass Evaluation Program (NTEP) jointly sponsored a project with the USGA and GCSAA to evaluate cultivars and mixtures used in over-seeding bermudagrass fairways.To test their performance, the trials were placed on ten golf courses where the research plots received golfer traffic and play.

but overall quality will most likelysuffer.• Since the performance of individualentries varied so much from location tolocation, management practices mustplaya big role in establishment andtransition. At the Orlando, Florida, site,the superintendent used chemical appli-cations (simazine) at light rates to hastentransition. This seemed to affect theperennial ryegrass more than the Poatrivialis. At the Charlottesville, Virginia,site, the superintendent did notphysically damage the bermudagrassbefore overseeding, resulting in betterestablishment and quality of the Poatrivia lis entries. Other locations, like

smooth. Weather patterns are importantin determining the ease of transitionfrom one species to another. In thecooler, northern sites, grasses that arestrong going into winter may not haveas much bermudagrass returning inspring. When the overseeding grass dies,there may not be sufficient bermuda-grass to provide adequate cover andquality.• There seems to be a balance betweenquality and cover of each species in falland spring. The higher the quality ofthe oversee ding early in fall, the moreoverseeding present in spring, alongwith reduced bermudagrass cover. Theresult is a more difficult spring transition.

variable from one season to the next, sooverseeding results can be dramaticallydifferent over time. Management prac-tices, including pre-plant preparation,maintenance practices during the winterseason, and management of springtransition, can significantly affect thequality of overseeding. Therefore, golfcourses that overseed fairways need tohave clear goals and objectives for thepractice as well as realistic expectationsof the outcome. Successful overseedingis still as much art as science.

KEVIN MORRIS is executive director of theNational Tuifgrass Evaluation Program,located in Beltsville, Maryland.

JULY-AUGUST 2004 21