UNDERSTANDING TURF MANAGEMENT

BLUEGRASSES

The grass species most common to thecool season, sub-humid to arid cli-

mates of Canada for sports turf isKentucky bluegrass.Kentucky bluegrass was introduced intoNorth America from Europe by the earlysettlers, probably as livestock feed duringthe ocean voyage or as mattress padding.The origin of the name "Kentucky" isprobably from Kentucky where seed wasfirst harvested from pasture stands. It mayalso be due to the species preference formedium textured soils formed from thedegradation of limestone, thus having arelatively high phosphorus level; featuresof the soils of the state of Kentucky.

The Bluegrass FamilyOf the more than 200 Poa species in theworld, there are only five bluegrass or Poaspecies which are commonly found in turf.While Kentucky bluegrass (Poa pratensisL.) is the most important and desirablespecies, a second species, Canada blue-grass or Poa compressa L., finds use inrestoration of droughty, low fertility areas.It forms an open, stemy turf which lacksthe strong, rhizomatous nature of Ken-tucky bluegrass. As a result it is of littlevalue for sports fields.Rough bluegrass, Poa trivia lis L., is astoloniferous species which also has lim-ited use because it lacks heat and droughttolerance, turning brown during midsum-mer stress periods. The above groundstolons do not provide the wear resistanceof Kentucky bluegrass. It does, however,have excellent cold tolerance making itworthy of consideration in areas wherewinter survival of Kentucky bluegrass is aproblem. .The renegade of the bluegrass species isthe widely distributed annual bluegrass,Poa annua L. This species is commonlyconsidered a weed grass due to its lowtolerance to wear, heat, drought and coldstress. The species is a prolific seed pro-ducer, particularly during the cool, moistspring, and spreads by the seed carried onmowing equipment and footwear. Asmany as 72 viable seeds per square inchhave been reported in golf greens. Theseeds do not have a dormancy period. thusthey may germinate as soon as they hit the

The 16th in a series by

R. W. Sheard, P.Ag.

soil surface. Poa annua also spreads bystolons and is shallow rooted, factorswhich reduce its wear tolerance on sportsfields.The fifth species of bluegrass is a recentintroduction from Europe, Poa sap inaSchrad. It appears to be related to annualbluegrass and has received considerableattention in Europe for sports fields. Initialinformation on the species indicates thatwhile slow to develop during the seedlingyear it becomes quite aggressive in lateryears. Its aggressiveness is in part due toheavy seed production and early seasongrowth. At the same time it is reported toprevent or inhibit the spread of annualbluegrass when managed with high nitro-gen and water.

Kentucky Bluegrass AdvantagesThe most significant advantage of Ken-tucky bluegrass for sports fields is that inaddition to normal tiller formation it hasthe ability to spread by means of rhizomesfrom which new plants develop to colo-nize bare areas, giving it great recupera-tive potential. Thus under good growingconditions the stand heals rapidly follow-ing injury. The interlocking network ofrhizomes and roots within the soil, ratherthan above the soil surface as is the casewith stolon forming Poa species, also en-hances the wear resistance of Kentuckybluegrass.It has been estimated that a single Ken-tucky bluegrass plant can produce 20 to 60feet of rhizomes from the original shootbetween mid-June and mid-November.Each node on the rhizome is capable ofinitiating a new shoot and root system. Itis this rhizome system which makes Ken-tucky bluegrass the preferred species forsports fields.Additional advantages of Kentuckybluegrass are that it performs well under awide variety of soil conditions, showinggood heat and drought tolerance and thatit is winter hardy. Under high tempera-tures and/or water restrictions, however,Kentucky bluegrass will enter a period ofslow growth, often referred to as summerdormancy. With the return of fall rains theturf will resume normal growth in aboutthree weeks.

The optimum temperature for topgrowth is 21 - 24°C, and 15°C for rootgrowth. Root growth may continue below4.5°C, a factor favouring nitrogen uptakefrom late fall fertilization. It is interestingto note that higher temperatures stimulatethe emergence above the soil surface ofgrowing points of new tillers from nodeson rhizomes whereas lower temperaturesenhance the elongation ofthe rhizome.Kentucky bluegrass has a medium toler-ance to low soil oxygen levels which maybe caused by poor drainage or compac-tion. It is a salt sensitive grass as conduc-ti vities due to salts in excess of 4millimhos are known to be harmful. Itprefers a pH in the range of 6.0 to 7.0 butwill grow very satisfactorily at pH a 7.5which exists on many of our sports fieldsin Canada.

Kentucky BluegrassDisadvantagesKentucky bluegrass is slow to germi-nate, generally requiring two to threeweeks to emerge. Its use for the quickrepair of sports field turf, therefore, islimited. Light is required for geminationof all bluegrass species. Although the in-tensity of light is very low, seed buriedbelow 2 - 5 mm may never emerge.In a rating of shade tolerance bluegrassmust be rated as poor in relationship toperennial ryegrass, bentgrass and fine fes-cues. When the shade is caused by treesthe problem of shade tolerance is com-pounded by the demand of the tree forwater and nutrients.Ice damage is a problem throughoutCanada. Kentucky bluegrass is intermedi-ate between bentgrass and annual blue-grass in its tolerance to ice sheet injurywith bentgrass being the most tolerant.Kentucky bluegrass will tolerate up to 50days of ice cover (skating rinks) withoutdamage if adequate drainage exists to re-move water formed during thaws. A snowlayer between the ice and the turf signifi-cantly reduces the ice damage. Frost heav-ing may be a serious problem for late fallseeded bluegrass. Again the correctivemeasure is good drainage.Kentucky bluegrass is a relatively heavythatch former. While thatch adds resil-

iency to turf, excessive thatch contributesto disease problems. Topdressing or cor-ing practices may have to be consideredfor those areas of the field where play isnot intense.

Cultural PracticesThe recommended seeding rate for Ke~-tucky bluegrass is 1.0 - 2.0 kg/lOO m .This seeding rate will pr£vide 4.8 to 9.6million seeds per 100 m ; about 5 seedsper square centimetre.There are over three dozen culti vars ofKentucky bluegrass available for use inCanada (see Sports Turf Manager, Vol. 8,March, 1995). Generally a blend of two ormore cultivars is preferred to capitalize onthe slightly different attributes of each in-dividual cultivar.Kentucky bluegrass is responsive tophosphorus fertilization, particulary dur-ing the establishment period. A high ratingon the soil test is desirable during thisperiod. Where this initial high level ofphosphorus fertility is achieved and clip-pings are not removed minimal phospho-rus fertilization may be required in futureyears.Kentucky bluegrass has a medium de-mand for nitrogen feqilization. Generally.25 to .75 kg N/lOOm per growing monthis required for good growth, howeverthese rates should be adjusted according tothe sports turf managers experience in thecolour and density he achieves from nitro-gen. Potassium should be applied accord-ing to the rate suggested by a soil test.Alternatively a rough guideline is one kgof K20 for every two kg of nitrogen.Disease on sports field turf is generallynot a problem. Helminthosporium leafspot, Fusarim patch (pink snow mold) andTyphula blight (grey snow mold) may bea problem under some conditions butchemical treatment is seldom necessary.In recent years grub damage to sportsfields from chinch bug and Europeanchafer has become a problem in Ontarioand Quebec. The insects damage the rootsystem drastically which reduces the wearresistance of the turf. Where the grubpopulation warrants chemical control isnecessary.The optimum cutting height for Ken-tucky bluegrass is one to two inches withthe higher height preferred for sportsfields. Cultivars have been developed forlower mowing heights for use on golf fair-ways but greater wear tolerance has notbeen shown to be associated with thelower mowing height.

their size, are very difficult to dry. It is alsoconsidered advisable in to remove the tarpno later than the morning after the game inorder to maintain turf colour. The grassshould be cut before the installation of thetarp. With freshly cut grass, once the tarpis removed it was found the grass willrecover more quickly from both the weightof the tarp and foot traffic on the tarp.Routine maintenance is minimal. Thetarps are 100% polyester and very, verytough and durable. We lay them out onasphalt under our stadium to clean wherethey are broomed off and hung to dry, ifnecessary. Although not extremely heavy,they are very awkward to handle. At sea-sons end we have our Housekeeping De-partment steam clean them so that theylook practically new again. They can alsobe washed with soap and water. They areplaced in an unheated area for storage,summer and winter, with no adverse ef-fects.The application of pesticides or fertiliz-ers just prior to putting the tarp down is ano-no!I would recommend these tarps to any-one whose fields get continuous heavywear. Itmay be used on soccer or footballfields and on baseball diamonds to coverareas for batting practice.Two companies that I am aware of thatsell these blankets are - Warren's TurfNursery, Inc. out of Indianapolis, Ind. andCovermaster, Inc. in Rexdale, Ontario.The material is available in differentlengths and widths.If you wish to save time and money onmaintenance I would suggest you considerpurchasing these tarps. Even if you haveartificial turf (heaven forbid), they willprevent wear in a heavy use area. Try them,you will like them.

Bench Tarps Will Help YouMichael J. Bladon

Head, Grounds Dept; U. of G.

A few years ago we had just finishedsodding the bench areas in Gryphon

Stadium at the University of Guelph whenI happened to read an article on Sports Turfand saw an advertisement for geotextileGround Blankets or Bench Tarps.They seemed to be the answer to one ofour maintenance problems. Each year wefound people were wanting to get on thefield earlier in the spring. At a time whenwe were trying to refurbish the fields, thenew, young tissue and the crown werebeing destroyed in the high traffic areasaround the bench. Hence we had a yearlyresodding job to do. Sodding was an auto-matic $2,400 expenditure, just for the sod.This compared to the tarps which todaywould cost $ 560.00 each, plus freight.We decided to purchased two tarps fromWarren's Turf Nursery of Indianapolis.The tarps measured 15ft wide by 75 ft longand weighed approximately 150 lb each.They are easily transported in a pick-uptruck, or if you have one, by a forklift. Thetarps have the leading edge (75 ft) andsides stabilized with a 2-inch wide,polypropylene reinforcement tape. This ischain-lock stitched to the fabric, with brasstooth grommets installed every three feetalong the front and sides. The tarp is a lightgreen in colour and the tape a darker green.On the day of the game, the tarps areremoved from storage, placed on a pickupor forklift and dropped off at the edge ofthe field. They are then unrolled in thebench area and spiked down using 6-inch"7" shaped spikes. The spikes are placeddown three sides of the tarp and the playersbenches are placed along the back lengthto hold that edge down.The tarps are removed after the Saturdaygame. This is very necessary, especially ifrain is expected because the tarps becomenot only heavier to lift, but also because of