LESCO, Inc., 20005 Lake Road, Rocky River. Ohio 44116 (216) 333-9250 Manufacturers, Formulators and Distributors for the Green Industr~ Measurable Increases in Fairway Bentgrass Populations Associated with Lightweight Mowing Randy Kane, U of I/CDGA Turfgrass Advisor • Dave Ward, Supt., Olympia Fields CC Randy Wahler, Supt., Knollwood Club Since the late 1970's and early 80's, increased attention has been focused on maintenance practices to improve manageabili- ty, playability, and aesthetics of fairways. These newer manage- ment strategies, the cornerstone of which is "1ightweight" mow- ing, not only increases the quality of the playing surface, but also appears to favor bentgrass competitiveness over Poa an- nua. Dramatic increases in percentages of bentgrass in fairways have been reported after only one or two seasons of lightweight mowing. Much discussion and experimentation among area super- intendents has insued, especially in regard to: which types of mowers should be used; whether to collect clippings; timing and amounts of irrigation, fertilization, and aerification; use and abuse of growth retardants; and other issues that may impact Poa annua survival, seed production, and competitiveness with the desired bentgrass. The consensus at this time is that you can indeed see increases in bentgrass with changes in management. But how much of an increase in bentgrass can you get? And, how soon can you get it? In order to try to answer these two questions, we began a study in early 1986 to measure increases in bentgrass popula- tions in fairways that were previously mowed in gang mowers, . but were subsequently mowed with lighter weight units (triplex • or pentaplex), Methods Two Chicago-area country clubs were chosen where mixtures of bentgrass and Poa annua were indigenous in fairways, and where superintendents had recently (1983-86) introduced lightweight mowing and other management strategies to reduce Poa competition. Also, the clubs were selected to represent two different environmental and geographical areas. To the north lies the Knollwood Club in Lake Forest, which is near the lake shore and exposed to cooler temperatures at various times of the year, At Knollwood, superintendent Ran- dy Wahler has converted a number of fairways using Roundup, and has been on lightweight mowing of all fairways since 1983 or '84 (Jake HF-5's). Certain fairways at Knollwood have received treatments of Cutless and TGR as well. On the south side, superintendent Dave Ward then at Ravisloe CC began lightweight mowing of fairways (GM 3's) on par 3s and decks in 1982. He added a few full fairways in 1984 and all fairways were used on the fairways during the study, as well as little or no N. Two separate methods were used to assess the increase in ben- tgrass in fairways over the next two seasons. First, a visual assessment of percentage bent vs. Poa was made on large scale areas of fairways. Several candidate fairways were selected at each club, than % bent was estimated on rectangular segments (plots) of fairway delineated by sprinkler head locations. Most • plots were 6-8000 sq. ft. Ratings were made in spring of '86 and again in spring of ' 88. The second method used was to map and measure individual patches of bentgrass within certain defined, relatively small plot (cont'd. page 6) • Equipment • Replacement Parts • Golf Course Accessories • Safety Products (800) 825-3726 LESCO Has It! Everything you need for professional turf management. • Fertilizers • Plant Protection • Seed • Irrigation -4-
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Manufacturers, Formulators and Distributorsfor the Green Industr~
Measurable Increases in FairwayBentgrass Populations Associated with
Lightweight MowingRandy Kane, U of I/CDGA Turfgrass Advisor •
Dave Ward, Supt., Olympia Fields CCRandy Wahler, Supt., Knollwood Club
Since the late 1970's and early 80's, increased attention hasbeen focused on maintenance practices to improve manageabili-ty, playability, and aesthetics of fairways. These newer manage-ment strategies, the cornerstone of which is "1ightweight" mow-ing, not only increases the quality of the playing surface, butalso appears to favor bentgrass competitiveness over Poa an-nua. Dramatic increases in percentages of bentgrass in fairwayshave been reported after only one or two seasons of lightweightmowing.
Much discussion and experimentation among area super-intendents has insued, especially in regard to: which typesof mowers should be used; whether to collect clippings; timingand amounts of irrigation, fertilization, and aerification; use andabuse of growth retardants; and other issues that may impactPoa annua survival, seed production, and competitiveness withthe desired bentgrass.
The consensus at this time is that you can indeed see increasesin bentgrass with changes in management. But how much ofan increase in bentgrass can you get? And, how soon can youget it? In order to try to answer these two questions, we begana study in early 1986 to measure increases in bentgrass popula-tions in fairways that were previously mowed in gang mowers, .but were subsequently mowed with lighter weight units (triplex •or pentaplex),Methods
Two Chicago-area country clubs were chosen where mixturesof bentgrass and Poa annua were indigenous in fairways, andwhere superintendents had recently (1983-86) introducedlightweight mowing and other management strategies to reducePoa competition. Also, the clubs were selected to represent twodifferent environmental and geographical areas.
To the north lies the Knollwood Club in Lake Forest, whichis near the lake shore and exposed to cooler temperatures atvarious times of the year, At Knollwood, superintendent Ran-dy Wahler has converted a number of fairways using Roundup,and has been on lightweight mowing of all fairways since 1983or '84 (Jake HF-5's). Certain fairways at Knollwood havereceived treatments of Cutless and TGR as well.
On the south side, superintendent Dave Ward then at RavisloeCC began lightweight mowing of fairways (GM 3's) on par 3sand decks in 1982. He added a few full fairways in 1984 andall fairways were used on the fairways during the study, as wellas little or no N.
Two separate methods were used to assess the increase in ben-tgrass in fairways over the next two seasons. First, a visualassessment of percentage bent vs. Poa was made on large scaleareas of fairways. Several candidate fairways were selected ateach club, than % bent was estimated on rectangular segments(plots) of fairway delineated by sprinkler head locations. Most •plots were 6-8000 sq. ft. Ratings were made in spring of '86and again in spring of ' 88.
The second method used was to map and measure individualpatches of bentgrass within certain defined, relatively small plot
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where r = rad~U:easuredn = # of rad 11
Percent Bent,grass -
change1988+13
198679
+ 6
# notes66
74+ 7
IVCHMOND
Fairwaycut less
6869
-+-13
KWD 8pgr
-
no62
78+15
11cutl./tgr
ISDERIE
6573
+ 9
16cutless
5869
+ 7
18year1st
6075
+22
RAV 21st year
6879
+17
8year3rd
5771
~
101st year16
year 54
-~+11.5
1st
Z.L74.6
173rd year
63.1~
•• , •• ", ••• TG' ,. '.,- are the lnltlal n 'B6 and scotts
for
two years",,"•• '0. "8;.0.'".' '"" ••• ';'h,"."h' .O"~'v•• , 0'note: Knollwood #lband #18 had been
were
in their Isisloe #10 fail'wayS
~:~or to . Bt: o~~~:r 1 applications1ightweight m - teffectsof Cut ess d #16re the apparen #11 KnollwooAl so of note ;~ and # 18 vs. untreated ed'in ryegrass.Fair-on Knollwood nnua but mcreas . ht mow-. rcentPoa a, of 1ightweigdecreased In pe h twere in their3rd year . crease in ben-R is10et a h d less mways at av . ing of thisstudy s owe f lightweightmow-
ing at the begmn f:I'rwaysin their1styear.o f fairways #10pared to a pulatlOns 0 .tgrasscom .. tialbentgrass po h' observation.ing. However, the ml which could accountfor t IS are slowerd #18 were hIgher, . further mcreasesan over tIme,(As % bent increa~es ation withinand more diffi~UI~lriablenature of the turf P:ft~:n individual
Because of tee broke down the ratmgs d 3 contain thea single faIrway, :'bedin Figure 1. Tables 2
han
tsome areas in-. s as descn . Note tabfaIrway opulation estimates. reas decreased yresultsof these p h 20-25% whIle other a . ate 10% in-d by as muc as n approxim
crease . on average, we saw a owever, siteto site7-1
0%. Agam, after2 years of study. H . creases in ben-crease in bentgr~ss h' h and in certain areas m ntT . qUIte Ig , fi r ten perce .variabl Ity IS more dramatic than Ive 0 (cont'd. page 8)tgrass can be
'ng cont'd.) t markers(Lightweight Mowl re located near permanen ped onsmall plots we and were map
areas. Thes~ 1 heads or valve boxes, d that they couldh Pnnk er marke so Isuc as S The sheets were fter season. nclear plastic Sh~~~S~xactsame location sea:~:n~ patches couldbe replaced m . the size and shape 0 f new patchesthis way, changes m d the appearance 0 . f '86
. d over tIme, an k d .n the sprmg 0 ,be mOnItore t d Patches were mar e. lble and easy to markcould be detec e . much more VISI P a and
d ' 88' patches were between bent, 0,'86, an , f color differences. because 0
in sprmg d patches were. lar shape drye. f the mostly Irregu . ommonly use
Surface areas t~e average radius teChnIq~:r csurfaces on theestimated usmg and other Irregu. g greensto measure puttIn
golf course:
"n" (~~~-~~:~:=~),.. SA .
here r = radiusw f radii measured .
n = # 0 . to estImate.ntendents ISResults surement for supen ki g at the big pic-mon mea (i e 100 n d
A com of entire fairways .. four Knollwoopercent bentgra~ows over all results from t~e Note the 11.5%ture). Table I~ fairways that were studle . period, also theand five RaVISoe. rass for the 2 year
•than other fairways areas. Some areas more than doubled inbentgrass coverage, up to as much as 90% bentgrass.
Note that as percent bent increased over time and patches ex-panded, the number of patches measured decreased, since manypatches grew together ("coalesced"). Of note also is the plotthat did not have a large increase in bentgrass (Knoll wood 16a),but did increase in perennial rye as Poa annua populationsdecreased. The increase in ryegrass observed here may berelated to use of Cutless and TGR growth retardants, which haveno inhibitory effect on perennial rye.TABLE 4. Small Plot - Individual Bentgrass Patch Measurements:
cerltgr3ss popul-3ti~ns
-turn = "_~e e;-:::1 cf f.3.~r',Ja'; "t'Jl-nal'o'J:-,-j" I
~~e~~_ :: :: 3~~~~:~:~~~~;~:::.~r ::1ecrease i n ~bzerved
TABL~ 3. Breakdown of Fairway RatIngs - selected faIrways Knollwood Club ..Percent 8entgrass
Table 5 shows data on selected individual patches of ben-tgrass. These numbers were included only as a summary of ourobservations on patches; many patches could not be followedover two years because of coalescence. Note that patchdiameters increased two to three inches per year on average.These relatively small increases in patch diameter often led toas much as a doubling in surface area covered by the patch.
(cont'd. page 10)
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These dramatic increases in percent bentgrass in isolated areasare also evident when looking at the individual small plot/ben-tgrass patch measurements. Table 4 shows data from six suchplot areas. These results include percent bentgrass (totalarea)for each plot and the number of patches measured. These plotareas had clearly defined bentgrass patches, but generally hadlower percent bentgrass coverage at the beginning of the study
aturn = tee end of fairway ("turnaround")"'deck = approach to greenC% +/_ = percent increase or decrease in observed bentgrass populat.ions
-8-
TABLE 5. Increase in Oia.eter of Selected Individual Patches
(Lightweight Mowing cont'd.)
patct"1 diamet.er (iriJ •WITH 7% WIN
NEW COMBINATIONIN SLOW RELEASE NITROGEN
Spr 88350265219163
patch area (ln~ _
Spr 86 Spr87160 242123 179105 19260 114
Spr B821.0IB.O16.714.4
Spr 8717.615.0
15.612.0
Spr 8614.212.511.58.7
~1
note: a 2 - 4 inch increase per year in patch diameter was often seenbefore patches coalesced.
SummaryIt appears that the claims of increased bentgrass populations
following lightweight mowing have not been exaggerated! Insome fairway areas the rapid increase in bentgrass was quitesurprising. The reader should note that there were no controlareas or check plots that were mowed with heavy gang mowers.Therefore, the observed increases in bentgrass may have beeninfluenced by hot, dry weather patterns of 1986-88 or other en-vironmental factors that we could not detect. In other years,we may not have seen these increases in bentgrass; for exam-ple, the weather in '89 may have been more conducive to Poaannua, but we have no data for this.
Also, other management factors probably playa role in in-creasing bentgrass populations. For example, at Ravisloe, verylittle fertilizer has been added to the fairways (virtually no N)for the past few years, and irrigation and aerification practiceshave been changed. Also, as mentioned at Knollwood, the useofpgr's may have had an effect. In any case, we have seen fromthis study what the potential for increasing bentgrass popula-tions can be, given appropriate management inputs and favorableenvironmental conditions .
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