Routine vertical mowing is a key management ikUYUgrassis the Rodney Dangerfield of HISTORYAND BACKGROUND practice to control turf - it gets no respect. While many thatch and maintain Kikuyugrass ( clandestinum) is a warm- good playing quality Kcourses fought the invasion and spread of season grass that is native to the Kenyan highlands on kikuyugrass kikuyugrass for decades, others have learned to of Africa. It is a course-textured grass with a rapid fairways. manage this grass to provide good playing quality growth rate, and it is commonly used as a forage on tees, fairways, and rough. Why the change of grass and turf grass in mild coastal climates and heart? Some courses had no choice but to learn sub-tropical regions. The spread ofkikuyugrass to manage their former enemy as it gradually was aided by the Dutch, who brought the grass spread over most of the course. Other courses from to and during did not have the budget or resources to control the Boer War. Kikuyugrass was eventually trans- infestations with multiple herbicide sprays, ported to other. areas and is now cultivated in physical removal, and sodding. As superintendents many mild climates throughout the world, learned more about the grass, they were able to including South Africa, Australia, New Zealand, adapt management practices to provide a dense, Mexico, Spain, Central America, South America, uniform turf with good playing quality. Although and portions of the United States. much of the literature to this point has focused Improvement ofkikuyugrass began in the 1950s on the control of kikuyugrass, this article will when the Australian government awarded a grant look at the culture and management of kikuyu- to a breeder to develop a seeded forage type grass as a fine turf for golf courses. for livestock. The rapid growth rate, palatability,

2 GREEN SECTION RECORD and high protein content made kikuyugrass an warm-season grass with a rapid growth rate. The ideal forage for cattle and livestock. The breeder, leaf width ranges from Ys" to X", comparable to Dr. Whittet, developed the cultivar that bears his Japanese lawngrass (Zoysia japonica) and St. name and sold the first 22 lb. batch of seed to the Augustinegrass (Stenotaphrum secdundatum).The Eykamp family for commercial seed production wider leaf blade is typical of the native types, in New. South Wales, Australia, where the Whittet while the narrow leaf blade is typical of improved variety is still grown today. varieties under intensive management. The leaf The establishment ofkikuyugrass in the United blades are flat and pointed at the tip and typically States occurred in 1918 when it was imported to grow in length from 1" to 10". Leaf color is a Pacific Palisades, California, as an erosion control medium to lime-green that some golfers and for ditch banks, and it gradually spread to the superintendents find objectionable. coast and inland valley areas. Many golf course superintendents and homeowners misidentified the grass as St.Augustinegrass due to the similari- ties in leaf blade width, color, thick stolon, and dense canopy. From California, the grass was transported and spread to several states, including Hawaii, Arizona, and Texas. Don Eykamp, son of the original grower, brought kikuyugrass seed to the United States in 1995 with the intention of producing seed and improving the species for the American forage and turf market. The main stumbling block was that kikuyugrass was listed as a noxious weed in most states due to concerns that it might be a host for an insect or a fungus that could devastate the United States millet crop. The host plant relationship was disproved, but the federal govern- ment continues to list kikuyugrass as a noxious weed, citing that it has an invasive growth habit. The status of kikuyugrass currently is under Long considered review, and a ruling by the governing agency, Kikuyugrass is often confused with St. a noxious weed, APHIS, is expected in the coming year. Augustinegrass due to similarities in texture, kikuyugrass is now In the meantime, seed production of Whittet color, growth habit, and the thick, fleshy stolons. considered a desirable went forward in Arizona under special permit. Kikuyugrass is distinguished by the pointed leaf turf by an increasing During this time, further improvement in kikuyu- tip, flat leaf blade, and the long fringe of hairs that number of golf courses in temperate grass occurred in the seed fields of Arizona as a parallels the stem near the leaf collar. In contrast, climates. result of natural selection. A patch ofkikuyugrass St. Augustinegrass has sharply folded leaves and with a finer texture and improved density was blunt leaf tips. Another distinguishing characteristic observed in a field of Whittet. The seed from the of kikuyugrass is the prominent anther and white unusual patch was replanted, and the progeny filament that extends above the canopy on closely displayed the same desirable characteristics, cut turf. The white filaments typically are visible resulting in the new variety Arizona-1 (also in the spring and fall, but they can be seen called AZ-1). throughout the year in some locations. The white Today, kikuyugrass is managed as the primary filaments return within a day of mowing, giving turf in fairways and rough at several golf courses, the turf a silvery cast. The female part of the including prominent PGA Tour stops Riviera flower is near the base of the plant, and the seed is Country Club, Torrey Pines Golf Course, and formed within the leaf sheath. The seeds are La Costa Resort and Spa. rounded and dark brown, approximately Ys" in length. KIKUYUGRASS CHARACTERISTICS The growth rate of kikuyugrass is very rapid Kikuyugras~ has been described as "bermudagrass under warm, moist conditions. Shoot extension on steroids." It is a coarse- to medium-texture can exceed 1" per day at the height of the grow-

JULY-AUGUST 2003 3 ing season. Active growth occurs at temperatures significantly restricted in dry soil, causing the turf between 60° to 90°F, and it can survive well at to become puffy and more prone to mower temperatures near 100°£ Kikuyugrass sustains scalping. active growth and retains color at temperatures The rapid growth rate and thick mat layer below 60°F, when most other warm-season associated with kikuyugrass contribute to excel- grasses exhibit a loss of color and a slower growth lent traffic tolerance and recovery from divot pattern. In California, kikuyugrass may not go injury. The rapid growth rate is both a benefit and dormant during the winter along the coast, a challenge for maintenance. Excessive thatch although it tends to enter dormancy from late contributes to spongy surface conditions, mower November until February in colder inland valley scalping, and diminished quality. If left unmowed, Kikuyugrass responds locations. Kikuyugrass appears to have the best kikuyugrass has been observed growing over well to applications of winter color retention of all the warm-season fences, up utility poles, and into trees and shrubs. the growth regulator trinexapac-ethyl.A grasses and can tolerate light frost without a loss Under routine mowing and maintenance, it can stolon from an untreated of color. invade greens and tees unless a routine edging area (top) exhibits a Kikuyugrass spreads by stolons, rhizomes, and and hand-picking program are in place to control wider leaf blade and seed. The thick, fleshy stolon and relatively wide encroachment. Kikuyugrass provides good play- greater internode length leaf blade contribute to a somewhat open growth ing conditions and ball support when closely compared to a stolon habit at mowing heights above 1WI. Canopy mowed, but the heavy thatch layer tends to limit from a treated area (bottom) that displays a density is significantly improved at mowing ball roll on fairways and provides unpredictable finer leaf blade, darker heights below %". Rooting occurs at the nodes of bounces on the putting green approach. It can be green color, and shorter stolons under moist soil conditions. Rooting is especially treacherous in the rough, where the internode length.

4 GREEN SECTION RECORD A distinguishing thick stolons and wide leafblades tend to grab the courses in the United States had to propagate characteristic of club and make it difficult to extract the ball. their own sod in a nursery area, but commercially kikuyugrass is the Kikuyugrass tolerates a wide range of soil con- grown sod is now available in Southern California prominent anther and ditions. Optimum growth seems to occur in at a cost of approximately 85~ to $1.00 per square white filament that extends above the medium- to heavy-texture soils with a neutral to foot. canopy on closely cut alkaline pH. Like many warm-season grasses, Some courses have attempted to establish plugs turf, which can give kikuyugrass has good tolerance to heat, drought, of kikuyugrass in existing stands of bermudagrass the turf an objection- and salinity. It prefers adequate soil moisture but using a specially modified aerifier that removes 2" able silvery cast but survives drought with a slight loss of color and a to 3" diameter cores for transplanting. The plugs does not affect playing quality. reduction in growth rate. can be slow to establish even if planted in the fall when bermudagrass is less competitive. Plugs PROPAGATION AND ESTABLISHMENT planted on 12" centers in the fall will provide The irony of kikuyugrass is that it spreads rapidly reasonable coverage by the end of the next where it is unwanted, but it can be slow to estab- growmg season. lish in existing turf or when efforts are made to Sprigs collected following vertical mowing can actively cultivate and spread it. Control efforts are be used to establish kikuyugrass in bare or reno- usually abandoned once kikuyugrass populations vated areas. Stolons should be spread evenly over reach 30% to 40%. At this point, most superinten- the soil, pressed or spiked into the surface, and dents begin active programs to cultivate and topdressed with a light covering of compost to spread kikuyugrass to encourage a uniform stand. retain adequate moisture. Good establishment is The primary methods of propagation are sod, usually evident within 4 to 6 weeks when plugs, sprigs, and seed. The most successful temperatures are above 60°£ method of establishment is transferring sod to Seed can be established on bare soil with provide a solid turf cover. Until recently, golf relative ease. The recommended seeding rate is

JULY-AUGUST 2003 5 Yz lb. per 1,000 sq. ft. or 25 lbs. per acre. The germination percentage of the seed is approxi- mately 85% to 90%, and germination is usually evident within 6 to 10 days when soil tempera- tures are 65°F or above. Seeding into existing turf has been a challenge for many superintendents. The recommended planting method is to lighdy dimple the surface with a core aerifier, broadcast the seed at the rate of lIb. per 1,000 sq. ft., followed by a very light covering of compost. Ample moisture is critical during the germination and establishment period. Efforts to slit seed kikuyugrass into existing turf generally have been unsuccessful.

KIKUYUGRASS MANAGEMENT While kikuyugrass can survive with only a moderate level of maintenance, a more intensive program is necessary to provide optimum playing conditions. Components of a successful manage- ment regime should include frequent mowing, thatch control, carefully controlling nitrogen applications, irrigation management, pest control, and other routine management practices . • Mowing. Kikuyugrass tolerates a wide range of mowing heights from X" on tees and collars to greater than 2" in the rough. Because of the rapid growth rate, frequent mowing with a motor- driven reel mower is necessary to provide good surface quality and minimize scalping. Heavier cutting units are preferred over lightweight mowers because the added weight pushes the reels further into the turf canopy to help control thatch and provide a better quality cut. Daily mowing is required when the cutting height is less than Yz", such as on tees and collars. Optimum cutting heights for fairways range from Yz" to %", with a mowing frequency of four to five times per week during the active growing season. It is recommended to maintain kikuyugrass rough at a mowing height of lYz" and not more than 2" to avoid excessively difficult conditions for the average golfer. Mowing of the rough normally is required two times per week during the active growing season. Ignoring recommended mowing frequencies can contribute to mower scalping and an unsighdy appearance throughout the course. Once kikuyugrass is scalped, it can be slow to recover. To reduce scalping injury, some super- intendents begin fairway mowing in the early spring at Yz" and gradually raise the cutting height to W' by mid November, which also provides additional mat and wear tolerance during the

6 GREEN SECTION RECORD Opposite page: Advantages and Disadvantages of Kikuyugrass Kikuyugrass has a rapid growth rate and Advantages Disadvantages can develop a dense thatch layer as Excellent traffic tolerance Medium to coarse texture observed on this Rapid recovery from wear and divot injury Rapid thatch accumulation bunker lip. Good heat, drought, and salinity tolerance Medium to lime-green color Best winter color retention of the warm-season grasses Persistence of white filaments/anthers Active growth and color retention at temperatures < 60°F above the turf canopy Competes against weed invasion Tendency for mower scalping' Tolerates a wide range of soil and water conditions Frequent mowing required to control rapid growth Low nitrogen requirement (2-3 Ibs.per 1,000 sq. ft. per year) Sensitivity to herbicides

winter. It is important to point out the accelerated Research at the University of California at wear on mowing equipment when maintaining Riverside showed that applications of 16-16-16 at kikuyugrass. The added wear typically reduces the the rate of lIb. actual nitrogen per 1,000 sq. ft. in expected life span of mowers by 10% or more. April,June, and August produced the best visual • Vertical mowing. Vertical mowing is an quality while minimizing scalping injury. Many important program for controlling rapid thatch superintendents prefer to apply 2 lbs. actual nitro- accumulation during the active growing season. gen per 1,000 sq. ft. in the late spring using a Studies at the University of California at Riverside slow-release carrier and supplement with monthly showed that optimum quality was achieved with applications ofYs lb. to X lb. of nitrogen per 1,000 three vertical mowing treatments (April, July, sq. ft. through the active growing season. Kikuyu- September) at approximately the depth of the turf grass responds well to applications of chelated iron canopy (Y2"). Because of the heavy yield of clip- and manganese to enhance green color without pings that must be removed and swept following promoting excessive growth. Iron is often applied such a treatment, many superintendents prefer to monthly with light rates of nitrogen as part of a vertical mow lightly, approximately X" below the spoon-feeding program. Applications of phos- turf canopy, on a monthly schedule from April phorus, potassium, and other nutrients should be through September. made based on the results of annual soil tests . • Aeration. Core aeration should be performed • Water requirements. Kikuyugrass will take a minimum of one time per year and preferably as much water as you can give it, but it prefers two to three times per year to aid in thatch con- evenly moist soil conditions for active root growth trol, encourage healthy root growth, and promote and development. Good irrigation coverage is rhizome development. Additional treatments will important to prevent localized dry spots and loss be necessary where excessive thatch is a problem. of root growth that contributes to puffy surface Kikuyugrass also benefits from deep aeration (6" conditions and mower scalping. Growth can be to 10") with a solid-tine aerifier in the spring. controlled to some degree by restricting irrigation The deep aeration treatment does a better job of as long as the soil does not become too dry. relieving soil compaction and also contributes to Kikuyugrass is drought tolerant but appears to better air and water movement for healthy root require more water than other drought-tolerant growth and rhizome development going into species such as bermudagrass . summer . • Pest control. Kikuyugrass is sensitive to most • Fertility. Kikuyugrass is very sensitive to commonly used broadleaf herbicides, which can nitrogen applications, requiring only 2 to 3 lbs. of result in discoloration and suppressed turf growth nitrogen per 1,000 sq. ft. annually. In some cases, following application at recommended label rates. the nitrogen supplied by effiuent water is adequate Many superintendents use a combination of 2,4- to sustain active growth without the need for D, mecoprop, and dicamba at X to Y2 the recom- supplemental applications. Excessive levels of mended label rates to control broadleaf weeds nitrogen further accelerate the already rapid when the turf is actively growing. Kikuyugrass growth rate and contribute to mower scalping. is very sensitive to triclopyr and MSMA, which

JULY-AUGUST 2003 7 , Ii! , control encroachment near greens is to establish Key Points for ~he Successful the collar with perennial rye grass and treat Management of Kikuyugrass encroaching stolons with recommended label Mow frequently with a heavy,motor-driven reel rates of quincWorac or a combination of MSMA mower and triclopyr. , light vertical mowing three or more times during , the active growing season , i CONCLUSION Core aerate to control thatch and encourage root and rhizome growth Superintendents have learned to successfully manage kikuyugrass as a fine golfmg turf for fair- Maintain even moisture ways, roughs, and even tees by embracing the ft. ,Li~it nitrogen to 2-3 Ibs.per I,000 sq. per year strengths of the grass and overcoming the prob- Edge greens and remove stolons by hand to lems with creative maintenance practices. The control encroachment same was done in the past with bermudagrass and Use trinexapac-ethyl to enhance color and seashore paspalum, which were considered by density many to be invasive grassy weeds until plant breeders took the initiative to improve the turf are commonly recommended for control in characteristics of these grasses. With recent unwanted areas. Applications of clopyralid do not advances in biotechnology and plant breeding, appear to cause any damage and can be used to there is ample opportunity to develop new control certain broadleaf weeds without damaging varieties of kikuyugrass that capitalize on the the turf. Although kikuyugrass is reported to have positive attributes of winter color retention, wear no disease problems, many courses in California tolerance, and low fertility requirement while are experiencing significant damage from brown working to improve the texture and winter patch and take-all patch. Research by Stowell and hardiness and reduce rapid thatch accumulation. Gelertner of PACE Research Institute indicates It is interesting to see the beginning of such that applications of manganese sulfate at the rate advances with the recent release of AZ-l kikuyu- of lIb. of material per 1,000 sq. ft. can suppress grass, and with luck and hard work, there will be take-all patch and aid in turf recovery while more cultivars to follow. In the meantime, more reducing the need for fungicide sprays. and more courses are taking a kindly look at • Use of plant growth regulators. Kikuyu- kikuyugrass and realizing that their former enemy grass responds well to routine applications of can become their friend in an effort to provide trinexapac-ethyl during the active growing good golfing conditions throughout the year. season. Research by Stowell and Gelertner of PACE Research Institute found that montWy REFERENCES applications of trinexapac-ethylliquid from April Beard,]. B. 1973. Tuifgrass: Science and Culture. Prentice-Hall, through September at the rate of 0.2 oz. to 0.5 Ine. Englewood Cliili, N.J. oz. per 1,000 sq. ft. dramatically enhanced color Cockerham, Stephen, R. Kahn,V Gibeault. 1998. Kikuyu- and density while reducing scalping injury and grass Cultural Practices. California Tuifgrass Culture.Vol. 48, thatch formation. Rat~s of the WSB formulation Nos. 3 & 4. of trinexapac-ethyl should be reduced by half to Culley,James. Kikuyugrass - First by Force, Now by achieve the same results. Temporary yellowing can Choice. CalifOrnia Fainvays. November/December 2002. occur following the first application of trinexapac- pp.16-17. ethyl, but turf color recovers within two weeks Ormsby, David. Kikuyu: Is it always a weed? New Zealand after the first application. Discoloration can be Turf ManagementJournal. February 1996. pp. 9-10. masked by the addition of nitrogen and chelated Research Update: The Kikuyu Debate Continues. Grounds iron at light rates to the spray mixture. Maintenance. May 1998. p. 82. • Controlling encroachment. Stolons of Cooley, Richard. Personal communication, March 15,2002 . kikuyugrass can rapidly encroach into tees, collars, and putting greens if not actively controlled. Most PATRICK GROSS is the director if the USGA Green superintendents find it necessary to edge the Section Southwest Region} where an increasing number perimeter of greens everyone to two weeks ifcourses succesifully manage kikuyugrass on golf during the active growing season and remove any courses}including TOrreyPines} site if the 2008 encroaching stolons by hand. Another method to us. Open Championship.

8 GREEN SECTION RECORD