The Ins And Outs Of Zoysiagrass Fairway Management
Although establishing zoysiagrass is expensive, this turfgrass will typically require fewer inputs than other turf types to maintain a quality playing surface.
Utilizing turf types that deliver quality playing conditions with fewer inputs is a key consideration for golf facilities as they continue to work toward becoming more sustainable. For many regions, zoysiagrass helps accomplish this goal.
When compared to cool-season grasses, warm-season grass like zoysiagrass requires less water, has superior heat tolerance and fewer pest concerns. These qualities contribute to consistent, quality playing conditions through the stressful summer months. Additionally, many zoysiagrass cultivars are quite tolerant of cold temperatures and can be used throughout the transition zone. The dense canopy of dormant zoysiagrass turf also provides a more playable winter surface than bermudagrass.
Quality zoysiagrass fairways are produced through an understanding of the ins and outs of this turf; but before an agronomic program is developed, the most suitable zoysiagrass variety for a given location must be established.
Zoysiagrass Selection and Establishment
There are numerous zoysiagrass cultivars to consider. ‘Innovation’, ‘Meyer’ and ‘Zenith’ have excellent cold tolerance and are well adapted for the northern portion of the transition zone. In warmer regions, fine-bladed zoysiagrasses such as ‘Zeon’, ‘Zorro’ and ‘Trinity’ have yielded excellent playing surfaces. A recent research review provides a great discussion on other important characteristics to consider and details zoysiagrass cultivars that are commercially available in the U.S. (Patton et al., 2016).
Zoysiagrass can be established by sod, seed, sprigs or by sod stripping – i.e. installing strips of zoysiagrass sod and allowing them to fill in over time. Complete sodding is the preferred method for establishment given the added timeframe needed when seeding, sprigging or sod stripping. Sodding is not cheap and will require a significant initial investment (Patton, 2012). However, the excellent playing surface and limited amount of inputs required for maintenance make zoysiagrass a very appealing option throughout much of the U.S.
Once zoysiagrass fairways have been established, turf health and playability are balanced by building a sound agronomic program. The remainder of this article describes key components of a successful agronomic program for zoysiagrass fairways.
Cultural Management
One of the greatest strengths of zoysiagrass is its ability to produce a dense, thick mat of thatch intermixed with soil. This mat layer provides the support and resiliency to withstand traffic from thousands of rounds of golf. But too much of a good thing can be quite problematic and excess thatch can lead to poor playing conditions and an unhealthy growing environment. Turf managers rely upon a variety of cultural management practices to manage the zoysiagrass mat layer and prevent thatch and organic matter from becoming excessive.
Cultural management practices should be performed when zoysiagrass will recover quickest. Maximum zoysiagrass growth typically occurs when daily temperatures are 80 degrees Fahrenheit or higher. The rate at which zoysiagrass produces thatch and organic matter will determine how frequently cultural management practices need to be performed. Fortunately, the relatively slow growth rate of zoysiagrass means thatch and organic matter accumulates gradually.
Many golf facilities that have zoysiagrass fairways find that a single core aeration each year is sufficient to maintain acceptable quality fairways. This is generally true throughout the transition zone. However, golf courses located farther south that have a longer growing season and more golf rounds may find it necessary to aerate an additional time each year. If soil compaction is a greater concern than thatch or organic matter accumulation, less disruptive cultural practices like solid-tine aeration, deep-slicing or spiking can be advantageous.
Verticutting is another technique that is commonly used to manage thatch accumulation, but its use on zoysiagrass fairways is not as widespread as it is on fairways comprised of other turfgrasses. Zoysiagrass, unlike bermudagrass or creeping bentgrass, does not seem to respond well to aggressive verticutting. The lines created from verticutting can persist for many weeks and can be distracting to golfers. As such, this practice should be used sparingly and only in situations where excessive thatch accumulation must be corrected. Light verticutting or, better yet, mowing with groomers, can improve surface uniformity without causing noticeable lines that are slow to fill in. If the steering wheel of your golf cart begins to tug back and forth when driving down a zoysiagrass fairway, it is a good indication that there is too much thatch. Under such circumstances, verticutting would be recommended.
Mowing
Anyone who has spent time mowing zoysiagrass realizes it is arguably the most difficult turf to mow in a straight line. The stiff, bristle-like leaves can cause the mower to shift and float across the surface. The reason for this phenomenon is the high lignin content in the leaves. Zoysiagrasses have the highest lignified tissue concentration among turfgrasses, which is part of the reason zoysiagrass makes such an excellent playing surface that resists wear. However, the added rigidity of the leaves is hard on steel, so more effort is needed to maintain sharp mowing equipment.
When it comes to mowers, most superintendents managing zoysiagrass favor heavy cutting units with larger reel diameters that create more down pressure. Lighter equipment may glide across the surface, making a consistent, high-quality cut challenging to achieve.
Washboarding can be a unique problem for zoysiagrass fairways. The uneven pattern of turf is associated with excessive thatch and can be more pronounced when mowing patterns are not rotated frequently. Even a properly adjusted, sharp mower cannot overcome the issue. Washboarding indicates that there is excessive thatch, which is best remedied with verticutting.
The measured, even growth rate of zoysiagrass makes keeping up with mowing a relatively easy task. Usually, zoysiagrass fairways only need to be mowed a couple of times per week and at most three times per week during peak growth.
Ideal heights of cut for zoysiagrass fairways vary among cultivars and geographic region. In the upper transition zone, where cultivars like ‘Meyer’ are prevalent, heights of cut range from 0.500 to 0.625 inch during the growing season. As you move farther south, it is not uncommon for cutting heights to range from 0.400 to 0.500 inch. Fairways mowed at the lower end of this range will produce a tighter lie, while mowing at heights near the top end of the range will produce a lie that makes it easier for a golfer to sweep the ball, which can be helpful for less-skilled players. The abilities of golfers that regularly play the golf course should be given serious consideration when selecting an appropriate mowing height.
Similar to bermudagrass, raising the height of cut in advance of dormancy can reduce winter injury and provide more leaf surface for better playing conditions during dormancy. A good rule of thumb is to begin raising the height of cut 0.1 to 0.25 inch over a period of four to eight weeks during the fall prior to dormancy. In areas like St. Louis, Missouri, heights of cut are typically raised immediately following Labor Day.
Disease Management
Zoysiagrass is very disease tolerant relative to other commonly planted fairway turf types. The only habitual disease concern is large patch, incited by the fungus Rhizoctonia solani. With proper fertility, moisture management and preventative fungicide treatment, this disease can be controlled very effectively.
Controlling moisture and improving drainage where soils tend to stay wet can significantly reduce the prevalence of large patch. Excessive fertility, specifically nitrogen, should be avoided as this can lead to more thatch. However, recent field research has demonstrated that reasonable amounts of nitrogen applied during the fall and spring does not exacerbate large patch and can improve turf recovery (Miller et al., 2016).
For sites with a history of disease damage, or for those that cannot tolerate any blemishes, a preventative fungicide treatment is recommended. The key is to select an appropriate fungicide and apply it when the fungus is active. Effective fungicides labeled for large patch on zoysiagrass include chemistries in the DMI, dicarboximide, SDHI and QoI classes. A number of these active ingredients are available in post-patent formulations, which can lower treatment cost.
The current recommendation is to treat turf during the fall when soil temperatures are between 50- and 70-degrees Fahrenheit at a 2-inch depth. Under most scenarios, a single application at the correct timing will provide sufficient control. A subsequent application three to four weeks later can increase the likelihood of successful timing and may prove beneficial if environmental conditions conducive to disease development persist.
A spring application as the turf is breaking dormancy is also effective. One popular large patch control program is to make a single preventative fungicide application during the fall and follow up with a spring application if any disease breakthrough occurs. This reduces the amount of fungicide required since entire fairways rarely need to be treated the second time.
Fairy ring is another disease that can diminish zoysiagrass quality. Symptoms can appear throughout the year depending on the specific fungi responsible. Disease symptoms are typically scattered throughout a fairway. Therefore, spot treatments are recommended to reduce the overall cost of control. Granular fungicide formulations, such as Heritage® G and Pillar® G, are great options for controlling fairy ring. These products can be easily delivered to affected areas, eliminating the need to fill up a large spray tank to only treat an isolated spot.
Water Management
As with any turfgrass, water management plays a crucial role in balancing turf heath and playability. When compared to cool-season turfgrass cultivars, zoysiagrass requires significantly less water. Lush, green turf should not be the goal of a zoysiagrass water management program. Managing turf that is occasionally moisture stressed will maximize both turf health and playability.
Wetting agent applications offer additional benefits such as uniformly distributing water in the soil profile, improving irrigation efficiency and reducing the likelihood of localized dry spots. A large number of wetting agents are available and turf managers are encouraged to experiment with several options at their golf course to see which delivers the desired results. For more information on wetting agents, please review the USGA Green Section Collection, “Understanding Wetting Agents.”
Zoysiagrass species are generally moderately tolerant to salinity and therefore can utilize recycled water. One factor to consider when using such water sources is the amount of nitrogen present within the irrigation water. Zoysiagrass does not need as much nitrogen as many other turf species and excessive nitrogen could enhance thatch accumulation and disease development.
Fertilization
Annual rates of 1 to 2 pounds of nitrogen are generally sufficient on fairways (Patton et al., 2010). Golf courses in the transition zone, where zoysiagrass growth occurs from the end of May through September, will be at the low end of this range. As you move farther south, the amount of nitrogen required will gradually increase. A soil nutrient analysis should be conducted once a year to determine the fertilizer requirements for other macro and micronutrients.
Multiple applications should be made when using a soluble, quick-release nitrogen source. Avoid applying more than 0.75 pound of soluble nitrogen during a single application to prevent a flush of growth. If a slow-release product is used, a single application can provide season-long delivery.
Plant Growth Regulators
Many superintendents do not regularly apply a plant growth regulator to zoysiagrass like they would with other turf types. Their use is generally not necessary to maintain a tight playing surface if good fertility and mowing practices are followed. However, there are certainly instances where their use is warranted to prevent flushes of growth. Plant growth regulators may also be beneficial in advance of a prolonged rain event, to improve turf quality in shaded sites and to lessen seedhead production.
Seedhead development can negatively impact both the playability and aesthetics of zoysiagrass fairways. Some cultivars, such as ‘Diamond’, will produce a flush of seedheads during the fall and spring while others, like ‘Meyer’, only produce seedheads during the spring.
Recent research has shown that a single fall application of the plant growth regulator ethephon will reduce seedhead emergence during the following spring on ‘Meyer’ zoysiagrass. Application timing for ethephon to suppress seedhead emergence is approximately the same time of year as preventative applications for large patch disease and these two products can often be sprayed together to save time (Patton et al., 2018).
Spring treatments can also be effective at suppressing seedheads, but they require sequential applications. Making two spring applications would likely be cost-prohibitive for most golf facilities.
When applying plant growth regulators to adjacent turf surfaces, it is important to avoid rates that could harm zoysiagrass. The combination of creeping bentgrass putting greens and zoysiagrass fairways is a common grassing scheme in the transition zone. If trinexapac-ethyl is routinely applied to the putting greens, any overspray could cause significant damage to the adjacent zoysiagrass collar, approach and fairway turf. Zoysiagrass is much more sensitive to plant growth regulators than bentgrass, so any overlap could be detrimental. The use of GPS sprayers equipped with individual nozzle control can eliminate the risk of misapplication.
Preventing Winter Injury
While many zoysiagrass cultivars have adequate winter hardiness, exposed sites that are prone to wind desiccation and poorly drained sites can leave zoysiagrass vulnerable to significant damage and possible turf death. The importance of removing water from the soil profile when saturated conditions develop cannot be overstated. Positive surface flow and subsurface drain lines should be used to ensure waterlogged conditions do not persist.
Addressing shade issues is also critical to preventing winter injury. Trees located to the south and east of zoysiagrass fairways are the greatest cause for concern. Zoysiagrass is certainly more shade tolerant than bermudagrass, but it still requires a daily light integral of at least 10 to 26 moles of light (mol) per square meter per day depending on the cultivar, time of year and whether or not trinexapac-ethyl is used (Wherley et al., 2018). Areas of zoysiagrass fairways that do not receive adequate sunlight will lack density and be slow to green up in the spring.
The impact of trees on turf health does not end with sunlight concerns. Feeder roots from trees located near fairways will compete with turf for water and nutrients. The severity of drought stress cannot be readily discerned as zoysiagrass goes dormant and loses green color, so correcting these issues prior to dormancy can help avoid unexpected damage.
Trees that are negatively impacting turf health, whether by limiting sunlight or competing for water and nutrients, need to be removed to prevent turf thinning. If turf is weak going into dormancy, it will be more likely to die during the winter.
Zoysiagrass is very durable and therefore can withstand a great deal of traffic. However, some restrictions on golf cart traffic during dormancy may be warranted to prevent damage. Selective traffic restrictions can help prevent thin lies and a delayed spring greenup. Extra care is also needed to prevent wear and tear on zoysiagrass while maintaining other turf areas. Practices like mowing and rolling putting greens can injure dormant or semidormant zoysiagrass if turning and other traffic is not carefully managed.
Weed Control
Two of the most common weed concerns for those managing zoysiagrass fairways are bermudagrass and Poa annua. Controlling them requires persistence and patience.
Suppression of bermudagrass with minimal injury to zoysiagrass can be achieved with Turflon® Ester mixed with Acclaim® Extra or Fusilade® II (McElroy and Breeden, 2006). However, sequential applications will likely be needed over multiple years to eliminate severe bermudagrass infestations. Three applications made at 28-day intervals starting in June is recommended. Some minor turf discoloration will occur, so spot treating is encouraged.
Effective Poa annua control can be achieved wth the use of preemergence and postemergence herbicide treatments. In areas where zoysiagrass goes completely dormant, postemergence herbicide options could include nonselective herbicides.
If nonselective herbicides are used, they should be applied as early as possible in winter to avoid injuring the turf as it breaks dormancy. Applying such products to what appears to be a dormant, off-color turf in late February could delay spring greenup and possibly kill some plants. Dig into the turf canopy and inspect for signs of green tissue before making an application. If any green tissue is observed, a nonselective herbicide should not be used. Applying postemergence treatments when weeds are small will also yield greater control. As always, it is important that chemistries are rotated to avoid herbicide resistance.
Insect Control
There are limited insect threats to worry about when managing zoysiagrass fairways. Billbugs, both Sphenophorus parvulus and S. venatus vestitus, are the most concerning. They can damage the stems, roots and crowns of zoysiagrass, causing severe discoloration and, in some cases, plant death. Early larval stages are small and difficult to detect, and the symptoms can be mistaken for drought stress. Pitfall traps that catch adults as they lay eggs during the spring are the best way to confirm the presence of these pests.
There are several zoysiagrass cultivars that have shown resistance to feeding by hunting billbugs, including ‘Diamond’, ‘Zorro’ and ‘Cavalier’ (Reinert et al., 2011). In areas where billbug damage has been identified a preventive, long-residual, systemic insecticide such as a neonicotinoid and anthranilic diamide or biorational insecticides containing entomopathogenic nematodes can provide relief (Dupuy and Ramirez, 2016). Treatments should typically occur in late May to early June – the same time frame for controlling annual white grubs – to target both adults and larvae.
Conclusion
While the initial cost to establish zoysiagrass is certainly high, this turfgrass will typically require fewer inputs to maintain a quality playing surface than other turf types. When properly managed, zoysiagrass fairway playing conditions can rival that of any other turfgrass provided it has been planted in a suitable growing environment. Following fundamental agronomic practices is the best way to get the most benefit from zoysiagrass fairways and to ensure that golfers enjoy excellent conditions.
References
Dupuy, M.M., and R.A. Ramirez. 2016. Biology and management of billbugs (Coleoptera: Curculionidae) in turfgrass. Journal of Integrated Pest Management, 7(1):6; 1-10.
McElroy, J.S., and G.K. Breeden. 2006. Triclopyr safens the use of fluazifop and fenoxaprop on zoysiagrass while maintaining bermudagrass suppression. Applied Turfgrass Science, 3(1): 1-5.
Miller, G.L., D.T. Earlywine, R. Braun, J.D. Fry, and M.M. Kennelly. 2016. Influence of nitrogen source and application timing on large patch of zoysiagrass. Applied Turfgrass Science, 2(1).
Patton, A.J., G.P. Schortgen, J.A. Hoyle, M.S. Harrell, and Z.J. Reicher. 2018. Fall applications of proxy (ethephon) suppress spring seedheads of ‘Meyer’ zoysiagrass. Applied Turfgrass Science, 4(1).
Patton, A.J., B.M. Schwartz, and K.E. Kenworthy. 2017. Zoysiagrass (Zoysia spp.) history, utilization, and improvement in the United States: A review. Crop Science, 57(1): S37-S72.
Patton, A.J. 2012. Warming up in the transition zone. USGA Green Section Record, 50(20): 1-5.
Patton, A.J., J.M. Trappe, and M. Richardson. 2011. Influence of nitrogen fertility and mowing height on zoysiagrass management. 2010 USGA Turfgrass and Environmental Research Summary, pg. 6.
Reinert, J.A., M.C. Engelke, and J.J Heitholt. 2011. Hunting billbug (Coleoptera: Curculionidae) resistance among zoysiagrass (Zoysia spp.) cultivars. The Florida Entomologist, 94: 613-621.
Wherley, B., Z. Chen, C. Reynolds, and R. Jessup. 2019. Minimum daily light integral requirements for warm-season fairway/tee and rough cultivars: mowing height and growth regulator interactions. 2018 USGA Turfgrass Environmental Research Summary, pp. 124-137.
