The recent Golf Industry Show in San Diego, Calif., provided an opportunity to conduct the first ever Kikuyugrass Management Workshop, which brought together superintendents from California, Mexico, Portugal and even Kenya – the country where kikuyugrass originated.
Since there is very little information available on kikuyugrass management in scientific literature and industry publications, superintendents have had to learn for themselves how to best manage the aggressive growth habit of kikuyugrass and how to treat pests and diseases. Presenters and panelists included Dr. Larry Stowell, Dr. Wendy Gelernter, Dr. Marta Pudzianowska, Pat Gradoville, Fernando Varela and Maureen Kahiu. The following are a few highlights from the workshop:
- Dr. Larry Stowell gave an overview of kikuyugrass culture and nutrient requirements. Kikuyugrass tends to thrive in mild climates where both warm- and cool-season turf species don’t perform well. Nutrient requirements are very low, with recommended annual nitrogen applications in the range of 1.8 to 2 pounds per 1,000 square feet, phosphorus at 0.28 pounds per 1,000 square feet and potassium at 1.07 pounds per 1,000 square feet.
- Many of the superintendents in attendance reported using recycled water for irrigating kikuyugrass. Salinity tolerance of kikuyugrass is good at levels up to 6 deciSiemens per meter (dS/m) – or 3,840 parts per million (ppm).
- Dr. Wendy Gelernter discussed insect pests affecting kikuyugrass. White grubs from masked chaffer beetles are quite common and infestations tend to occur in the same location every year. The presence of grubs is strongly correlated to high soil moisture (volumetric soil water content of 20 to 25 percent). Preventive insecticide applications are best made in June or July, about two weeks after the adult beetles are seen.
- Dr. Marta Pudzianowska is leading a kikuyugrass breeding program at the University of California, Riverside. The initial goals of the program are to enhance winter color retention and drought tolerance while manipulating the genes of the grass from tetraploid (four sets of genes) to diploid (two sets of genes), which is expected to make the grass less aggressive.
- The panel of superintendents and workshop attendees shared information on various management programs including mowing, vertical mowing, and the use of plant growth regulators and colorants. All agreed that frequent close mowing in the range of 0.35 to 0.50 inch provided the best quality surface.
- Frequent vertical mowing is a common practice during the active growing season. The panel and superintendents in the audience reported a wide range of vertical mowing practices from light and frequent treatments – e.g., with blades set at 0.25 inch below the mowing height – to fewer and more aggressive treatments with the blades set to penetrate the soil. One course in Southern California reported good results with fraze mowing, with full recovery talking three to four weeks.
- Plant growth regulators are commonly applied to help control the aggressive growth of kikuyugrass, with trinexapac-ethyl (Primo®, Moddus®) being the most popular. Some superintendents were experimenting with applications of flurprimidol plus trinexapac-ethyl (Legacy®).
- Applications of trinexapac-ethyl and ethephon (Proxy®) made on Poa annua putting greens to control seedheads can cause discoloration and damage to kikuyugrass collars and green surrounds. Interestingly, the same combination is reported to be effective at controlling the silver filament (anther) of kikuyugrass.
An updated kikuyugrass management survey is being prepared and will be emailed to attendees of the workshop and other interested superintendents. If you would like to participate in the survey, please email Pat Gross of the USGA Green Section at email@example.com.
West Region Agronomists:
Patrick J. Gross, regional director – firstname.lastname@example.org
Larry W. Gilhuly, agronomist – email@example.com
Brian S. Whitlark, agronomist – firstname.lastname@example.org