Kikuyugrass, which is well adapted to the Mediterranean climate of Southern California, is in use on more than 25 golf courses in the area. Photo courtesy of Stover Seed Co.
What is kikuyugrass? A noxious weed, or a fairway grass that offers spongy lies? A drought-tolerant gift to arid Western states, or the scourge of mowers? With kikuyugrass, which has been described as “warm-season Poa annua” and “bermudagrass on steroids,” it seems superintendents and golfers either love it or hate it.
A native of East Africa, kikuyugrass (Pennisetum clandestinum) derives its common name from the Kikuyu people, who live in the area around Mount Kenya. It has been introduced in many areas across Africa, North and South America, Australia, Asia, and the Pacific.
Kikuyugrass has an aggressive growth habit that has led to its classification as a noxious weed by the U.S. federal government and several states. Nonetheless, kikuyugrass seed is still produced in California, Arizona and Texas — albeit with some restrictions — and seed and sod can be planted in nine counties in Southern California. It is well adapted to a Mediterranean-type climate and thrives on golf courses, particularly in Southern California and in inland valleys and coastal areas as far north as San Francisco.
The history of kikuyugrass in the U.S. is somewhat unclear. The Nov. 16, 1925 issue of the USGA’s Green Section Record states that kikuyugrass was first introduced to the U.S. by the U.S. Department of Agriculture in 1915 and was tested in California in 1916. However, the University of California’s Division of Agriculture and Natural Resources places the introduction of kikuyugrass to the state in 1918, when it was planted to prevent erosion on ditch banks.
In any case, kikuyugrass was let loose in the landscape, and the Record described it as thriving in “dry, semi-arid conditions, and in flooded, swampy places, ... in light, sandy loam and in stiff adobe.” In 1934, it found its way to the golf course when Riviera Country Club in Pacific Palisades, Calif., planted it on the slopes of the “Barranca,” more or less ensuring that the course would have kikuyugrass for years to come.
The aggressiveness and competitiveness of kikuyugrass is storied and can present definite maintenance challenges for golf courses. Stephen Cockerham, former superintendent of agricultural operations at the University of California-Riverside, wrote that he knew of a park where “stolons grew in one door of a small building and out the other.” Cockerham (and others) conceded that “(golf) balls sit up nicely on closely mowed kikuyugrass with minimal thatch,” but playing out of taller kikuyugrass in the rough “is a formidable task for golfers of any ability.” So formidable that golf course architect Paul Jansen wrote in his blog, “Golfers have been known to break their wrists playing out of kikuyu rough.”
Because kikuyugrass is not commonly used on golf courses, little research has been done, and much of the available information is from observations by university Cooperative Extension personnel and superintendents.
In 2010, more than 25 superintendents from golf courses in Southern California joined four scientists and USGA West Region director Pat Gross for a Kikuyu Summit at Mission Viejo (Calif.) Country Club to share their knowledge of the ins and outs of kikuyugrass management.
Frank Wong, Ph.D., then a specialist in Cooperative Extension at the University of California-Riverside, summarized the substance of the meeting: “The good things about kikuyugrass include color retention under cool weather, aggressive growth and drought tolerance. The bad things include the need for regular vertical mowing and thatch removal, and its susceptibility to diseases like gray leaf spot, (kikuyu) decline and large patch.” Larry Stowell of PACE Turf, who was also at the summit, expressed his opinion: “If you like gray leaf spot, brown patch and decline, you’ll love kikuyugrass.”
Superintendents at the summit reported some advantages of kikuyu, including low fertilization requirements, greater shade tolerance than bermudagrass, and drought tolerance. Although kikuyugrass is drought-tolerant, superintendents reported that effluent water can overstimulate growth in a grass known for being aggressive. The natural density of the turf also means that heavier reels are needed for mowing, and deep-tine aeration can be difficult. Frequent treatment with a PGR is necessary to prevent scalping.
Every turfgrass presents challenges, and a few golf courses have embraced those presented by the African grass that has made its home in California.
Teresa Carson is GCM’s science editor.