Key Takeaways

• Ever-increasing scrutiny on golf course water use, prolonged droughts and increasing water costs are driving courses to convert from cool-season to warm-season grasses.
• Costs for converting fairways to hybrid bermudagrass vary widely depending on soil preparation methods and whether turf is established via sprigging or sodding.
• A patient, well-executed conversion plan and course closure during establishment are critical to optimize the conversion.
• Golf courses report 25% or more in annual irrigation reduction for areas converted from cool-season grasses to bermudagrass.
   

Apply glyphosate (64-160 ounces per acre) with fluazifop (24 ounces per acre) and triclopyr (32 ounces per acre) to actively growing cool-season grasses or bermudagrass. Ideally the treated area should not be mowed seven days prior to and seven days following chemical application. This herbicide combination should be applied at least three times, and up to five applications may be necessary when bermudagrass is present. Courses often begin the spray program in late April or early May. However, some courses that are upgrading from one bermudagrass to another have enhanced success by chemically treating once or twice prior to overseeding during the year prior to renovation – then following up with three to five applications starting the following spring.

Do not plant sprigs or sod within seven days of the final application unless you remove fluazifop from the final application. The application interval should be 14-21 days. The key is allowing the existing turf to recover between applications. Continue providing adequate soil moisture throughout the application window and apply an available nitrogen source approximately one week after the first application at 1 pound of nitrogen per 1,000 square feet. Regrowth between applications is critical to achieve 85% or better control. An additional nitrogen fertilization following the second herbicide application will likely be necessary. The golf course can remain open for play during this process and although the color won’t be as green, golfers may enjoy the additional ball roll.

It is beneficial to disturb the soil surface between herbicide applications to encourage turf regrowth. Tools to consider include fraise mowing, core aeration, vertical mowing or dragging with a metal spring-tine rake. These strategies disrupt the organic mat that forms at the soil surface when the turf leaves, stems and stolons have desiccated. It seems that disrupting this mat encourages regrowth and allows new leaves to metabolize additional herbicide applications. It is critical to allow the remnant grass to recover before reapplying herbicides. The recovery process will likely require a four-week wait before herbicide reapplication. Be sure to communicate with golfers about the process and commit to this eradication program. No herbicide combination will yield the desired results with only one or two applications.

Preparing the soil for planting

Courses have used many different approaches to prepare soil for sprigging or sodding. The methods vary from minimally invasive – such as only scalping with a mower – to more aggressive practices such as grinding or pulverizing the soil. As you might expect, there is a wide range in cost and success rate depending on the method chosen, but you might be surprised at how successful minimally invasive approaches can be.

The no-till method

The least disruptive method for converting fairways to bermudagrass is to chemically treat them as described above and then use minimally invasive strategies such as vertical mowing, aeration and mower scalping to remove much of the living material growing on the surface.

This no-till process has been deployed at several California golf facilities. Courses that were sodding the new turf have had good success and courses that were sprigging have had only marginal success. Two courses, Hunter Ranch Golf Course and Turlock Golf and Country Club, planted ‘Santa Ana’ bermudagrass through sprigging and remained open for play during the conversion process. Several years later the fairways contain a mixture of ‘Santa Ana’ and remnant common bermudagrass. One might expect the more aggressive hybrid grass to outcompete common bermudagrass, but that has not been the case. Del Rio Country Club in Modesto, California, sprigged ‘Santa Ana’ bermudagrass on one of their nine-hole courses and closed for several months to grow in the new sprigs. The course closure resulted in much faster hybrid bermudagrass establishment and a greater percentage of ‘Santa Ana’ in the fairways. Several years later there is a mixed stand, but ‘Santa Ana’ is still the dominant variety.

For these courses, the no-till process produced a marginally successful turf conversion (approximately 50% hybrid) with sprigging at far less cost than sodding and employing soil modification strategies. However, courses that use the no-till strategy and plant sod rather than sprigs have enjoyed a greater percentage of hybrid bermudagrass years later.

Along with cost savings and less disruption, there are additional agronomic benefits to the no-till process. It leaves behind organic material that has accumulated for years, which will offer good moisture and nutrient retention for the new turf. If the soil has good physical characteristics, the no-till method avoids disrupting the soil structure and retains positive water infiltration. This may be somewhat surprising, but the no-till process typically expedites the grow-in and maturity process compared to tilling the soil.

Advantages to no-till conversion

• No-till plus sodding requires very limited course closure – only three to four weeks to lay the sod and approximately three weeks for establishment during the peak of summer. If sprigging, it is recommended to close for about 110 days. While several courses have kept fairways open during the conversion process, that strategy is not recommended due to marginal success.
• The no-till method is less expensive than pulverizing or otherwise tilling the soil.
• The no-till method is much less prone to erosion.
• The no-till method does not disrupt the current grades and is less disruptive to the soil. Pulverizing the soil requires regrading work and the soil disruption may result in poorly drained areas.
• The no-till process retains organic matter that has accumulated in the soil. This can be advantageous for providing water and nutrient retention when establishing the new fairway turf.
• The no-till method leaves the surface as is, while the more aggressive tilling practices will disturb the soil and could leave behind a bumpy surface.
   

Disadvantages to no-till conversion

• The no-till process does not address poor soil conditions. Fairway regrassing can be an important opportunity to improve rootzone conditions for the new turf. Many courses are plagued with very poorly drained soil and pulverizing or adding new material may be the best way to maximize success of the conversion process.

Soil grinding or pulverizing

Many courses that converted fairways to bermudagrass have utilized some form of soil pulverization prior to planting the new turf. There are generally three methods to till the soil: an asphalt grinder, a Blecavator or a RotaDairon. The asphalt grinder works well in compacted soils with rock. This large machine grinds up the soil to a depth of 8-10 inches. Sprinklers should be removed before grinding and replaced after the process is completed. The asphalt grinder can grind about 3-4 acres per day at a cost of approximately 5-7 cents per square foot. The result is a moonscape that will need to be graded with a box blade, bulldozer or similar tool and compacted prior to replacing the sprinklers and sodding or sprigging. Costs to finish grade, including compacting and resetting sprinklers, will be in the range of 20-25 cents per square foot. The asphalt grinder does not remove any material and therefore there is risk of remnant grasses making a return.

The Blecavator and RotaDairon are much slower than the asphalt grinder but yield a finer consistency to the prepared soil. The finer material is easier to smooth and reestablish the desired grade. This tactic worked especially well at Menlo Country Club in California, where several inches of organic matter at the surface was effectively blended with the underlying sand cap. The organic material and sand blend provided an excellent growing medium for the sodded ‘Santa Ana’ bermudagrass. These machines can prepare about 1 acre each per day and some courses have made double passes over the fairways, which slows the process but produces even finer particles. Similar to the asphalt grinder, these machines do not remove any material.

Some courses have incorporated sand during the tilling process to improve soil physical characteristics, while others have applied several inches of a sand cap after tilling and grading work is complete. Tilling-in sand or sand capping can be advantageous but these practices can also be disastrous. It is essential to characterize the soil characteristics and the sand characteristics through physical soil testing prior to making any decisions about sand blending or capping.

Soil tilling advantages

• The biggest reason to till the soil before regrassing is to improve soil conditions. Tilling will likely improve drainage and reduce compaction, but the soil will recompact once traffic returns and therefore the benefits may be temporary. Collecting physical soil tests well in advance of the project will help you determine if tilling is necessary and if adding well-draining material will be beneficial.
• Tilling the soil presents an opportunity to improve surface drainage and perhaps make architectural changes to improve playability.
   

Soil tilling disadvantages

• Tilling and finish grading the soil is expensive. Asphalt grinding will cost approximately 5-7 cents per square foot and Blecovator or RotaDairon costs are typically a few cents higher per square foot. These costs include sod removal on areas not accessible by these machines, such as around bunker banks. Finishing the grade and placing sprinklers will run an additional 20-25 cents per square foot. Costs will range from about $11,000-$14,000 per acre or about $330,000-$420,000 to till, finish grade and replace sprinklers for a typical course converting 30 acres of fairways.
• Soils develop structure over time, building macropores that assist with root development and drainage. Aggressively tilling a soil with good “tilth” will disrupt these channels and may reduce the soil’s ability to move water. This is another reason to collect soil physical tests prior to making the decision to till the soil. This expensive and disruptive strategy may not be necessary.
• Tilling the soil adds time to the project and the closure period. Contractors report asphalt grinding will add about seven to 10 days and using a Blecovator or RotaDairon may add three weeks to the project.

Fraise mowing

As previously mentioned, fraise mowing can be a useful strategy to encourage turf reemergence between chemical applications during the eradication process. It can also be used to remove some of the existing turf and weed seeds. Fraise mowing has a good track record of removing a majority of Poa annua plants and seedbank. However, fraise mowing cannot be expected to remove bermudagrass rhizomes. Fraise mowing typically costs from 6-12 cents per square foot, but this does not include costs to haul the debris off-site. Total costs will vary with depth and acreage.

Is it better to sprig or sod?

The answer to this question depends on who is writing the check. Sodding will cost 60-70 cents per square foot while sprigging will run from 8-15 cents per square foot. The sprigging materials and planting process is cheaper than sodding, but when lost revenue from additional course closure time is factored in the total cost difference may not be so great.

When converting from one bermudagrass to another, it is better to plant sod primarily for improved weed control. Sodding increases the success rate of establishing a dominant stand of the desirable bermudagrass with little remnant warm-season grass contamination. Additionally, sodding requires fewer inputs such as water, fertilizer and pesticides to achieve full establishment compared to sprigging. Sodding also ensures full turf cover and if laid between spring and the end of July will allow the new turf to establish a healthy rhizome population prior to winter.

Sprigging will require a minimum of eight to 10 weeks to allow for establishment. The sprigged area should be closed during this time unless the course is patient enough to manage through a four to five year conversion. If sprigs are planted late in the summer, the fairways may not achieve full cover and surely won’t establish a healthy rhizome population until after the second year. Under no circumstances should bermudagrass be overseeded the first year after planting.

As previously mentioned, there is a real possibility of underlying warm-season grasses resurfacing during the sprig establishment phase and contaminating the new fairways. Other warm-season annual weeds such as crabgrass, goosegrass, knotweed and purple nutsedge can also be troublesome. Where these issues are likely, apply the preemergence herbicide oxadiazon as a liquid prior to sprigging or utilize the granular formulation after sprigging. Given the nitrogen requirement during the establishment phase, applying oxadiazon with a granular fertilizer carrier is also a good option.

Advantages to sprigging

• Sprigging will cost 8-15 cents per square foot depending on the sprig rate, number of acres and course proximity to the sod farm. Sod will cost 60-70 cents per square foot.
• Planting with sprigs will not introduce a foreign soil to the fairways like sodding does. If planting into a sand cap, this is important.
   

Advantages to sodding

• From the final day sod is planted in an area, it could reopen for play in as little as two weeks, preferably three. This is a much faster turnaround time than establishing sprigs.
• Sodding will greatly improve weed control and limit resurgence of the existing grasses.
• Sodding requires less water, fertilizer and chemicals for establishment.

Sprigging methods and tips for success

A commonly used sprig planting machine is the Bermuda King, which spreads and cuts sprigs into the soil. These planters can typically plant 4 acres per day. Alternatively, courses have had success using a sod-to-sprig planter. These machines process sod rolls or slabs and shred the material before cutting it into the soil. They can be geared to plant the equivalent sprig rate of approximately 300 to 700 bushels per acre. This process reportedly expedites establishment time by omitting the “shock” that sprigs endure between cutting on the farm, transporting to the site and spreading on the soil by hand or hydrosprigging. The hydrosprigging machine also can add stress to the sprig material as it is thrust out of the hose.

Cutting the sprigs into the soil is an essential part of successful establishment. The soil must be softened through heavy watering and aggressive aeration to effectively cut the springs into the soil. Sprigs should be planted before 10 a.m. and watered immediately!

A machine called a Renovator is equipped with steel shanks that pulverize sod into sprigs and can cut sprigs into compacted soil on 6-inch centers. Discs and a roller push the sprigs into the soil 1.5 inches deep. This machine has been used extensively in southern Arizona and southern Nevada where compacted, poor soils are common.

Rolling fairways with a 2-6 ton asphalt roller is commonly done to push sprigs into the ground, along with producing a smoother, firmer playing surface. A smooth surface will yield better mowing quality. In some instances, courses that tilled the fairways prior to planting have seen mower scalping after turf establishment because the ground was not smooth. Once the turf is established, it will take years of topdressing to effectively smooth out any imperfections, so it’s very important to plant into a smooth surface.

Recommended sprig rate

Sprig rates for fairway renovation are higher than for new construction or sprigging into soil with no competition from remnant grasses. A sprig rate of 400 to 800 U.S. bushels per acre is common. A U.S. standard bushel has a volume of 1.25 cubic feet, a Georgia bushel is supposed to be 0.4 cubic feet and a Texas bushel may range from 0.4 to 1.23 cubic feet. While a higher sprig rate is more expensive, it expedites establishment and helps the new turf outpace regrowth of any remnant grasses. At higher sprig rates, full turf cover may be accomplished in about eight weeks from planting.

Ideal time to plant sprigs

This may seem counterintuitive, but it is not recommended to plant sprigs when it is hot and dry. Ideally, plant sprig material during hot and humid weather. Planting when hot and dry slows establishment and will require more inputs – especially water. Alternatively, research shows success planting dormant or near-dormant sprig material early in the year. A study completed in Arkansas in 2016 indicated dormant sprigging bermudagrass and zoysiagrass achieved full cover by the end of the season and performed just as well as summer sprigging with much less inputs. The authors stated that, “Dormant sprigging reached full coverage as fast or faster than traditional spring or summer planting dates at both locations, indicating that bermudagrass and zoysiagrass establishment can be achieved earlier in the growing season using dormant sprigging methods.”

Treat sprigs to aid establishment

Treating bermudagrass with fungicide prior to sprigging accelerates establishment. Coordinate with the sod supplier to apply a fungicide such as a combination product with fluxapyroxad and pyraclostrobin four to six weeks prior to cutting sprigs.

How long will it take for sprigs to establish?

Full turf coverage and playable conditions can be achieved six to 10 weeks after sprigging if the area is closed to allow for frequent irrigation and routine nitrogen inputs. In general, it is recommended to supply 0.25 to 0.5 pounds of nitrogen per 1,000 square feet per week for the first six weeks after planting.

Case Studies in Fairway Conversion

Many courses in California have converted to hybrid bermudagrass over the past 15 years and that trend continues in earnest due to rapidly rising water costs and imposed water limitations. Several examples of courses who have made the conversion are described below.

Birnam Wood Golf Club

Birnam Wood Golf Club in Santa Barbara historically maintained a mixed stand of cool-season turfgrasses, sometimes referred to as the “California Turf Surprise.” This turf composition produces acceptable playing conditions, but never delivers a premier golf experience and the water demand is higher than it would be for warm-season turf. Historically, Birnam Wood budgeted for about 185 acre-feet of water use annually (approximately 60 million gallons) with a cost of nearly $200,000 per year.

The golf course’s leadership recognized an opportunity to improve the consistency of playing conditions and reduce resource inputs, most notably irrigation water, by converting the cool-season turf to bermudagrass. In 2015 and 2016, the golf course converted 31 acres of fairway to ‘Santa Ana’ bermudagrass and converted the roughs to ‘Tifway 419’ bermudagrass. In addition, 7.2 acres of irrigated turf was replaced with low-water-use landscaping.

After the renovation, the golf course water budget is about 135 acre-feet annually, which is a 25% reduction in annual water inputs. The cost of water for the course has increased over 500% in the past decade and water costs today are nearly $11.00 per hundred cubic feet (HCF). At current prices, the 25% water reduction saves the facility over $100,000 annually. The conversion has also saved approximately $100,000 per year in fertilizer, seed and plant protectants. The cost of the project, which included minimal soil preparation and sodded bermudagrass, was about $1.25 million and within seven years the project paid for itself.

Menlo Country Club

Menlo Country Club in the San Francisco Bay Area converted the fairway on their sixth hole from perennial ryegrass to ‘Santa Ana’ bermudagrass in 2018 to see whether water savings and improved playability would justify converting all the fairways. Golf course superintendent Chris Eckstrom documented significant water savings on this fairway – noting that 25% savings over cool-season grasses is very realistic. Based on this success, in 2021 the golf course converted the remaining 33 acres of perennial ryegrass fairways to ‘Santa Ana’ bermudagrass and replaced 2.4 acres of turf with naturalized grasses.

The golf course realized a 20% water savings during the first year alone, while the fairway turf was still immature. Future water savings should be even greater. With a water budget of nearly $1 million annually and water costs increasing 5%-8% every year, the $2.6 million project – which included Blecavating the soil in fairways and sodding the bermudagrass – will pay for itself in less than eight years. Additional economic savings have been realized with reduced use of plant protectants, and golfers are pleased with the improved quality and consistency of the new bermudagrass fairways.

The Preserve Golf Club

The Preserve Golf Club in Carmel relies on rainwater to meet the irrigation needs for the 18-hole golf course. In drought years, there was not enough water to meet the demand of the cool-season turf and water had to be strategically shut off in lower-priority areas such as roughs, tee surrounds and even in some fairway areas. Golf course leadership realized that cool-season turf was not a sustainable playing surface given their climate and water supply. In 2016, the golf course converted nearly 27 acres of fairways to ‘Santa Ana’ bermudagrass. Fraise mowing was used to remove the existing turf, followed by pulverizing the soil and surface organic matter layer with a RotaDairon. Since the fairway conversion, the course is using 13%-14% less irrigation water annually. They were using about 75 million gallons per year, and now use about 69 million gallons. The water savings is less, however, than what other golf courses have achieved simply due to the amount of land converted. There are still 45 acres of cool-season turf on tees, roughs, green surrounds and greens. At some point it will be necessary to convert more of those areas to warm-season grasses to increase water savings further.

A common theme among these California golf courses is 25% or more annual irrigation reduction for areas converted from cool-season grasses to bermudagrass. Furthermore, in drought years or during water use restrictions, these golf courses are much better equipped to produce acceptable playing conditions. They are also in a better situation to promote turf recovery once water restrictions are removed or when rainfall returns. For these courses, bermudagrass delivers more consistent, firmer playing conditions throughout the year than the hodge-podge of cool-season grasses they had before. Eliminating thirsty cool-season grasses and planting hybrid bermudagrass has proven to be an excellent investment for these courses and others who are concerned about water use and drought resistance.

If you’re looking for site-specific recommendations about converting fairways at your course, USGA agronomists can provide practical recommendations tailored to your needs through the USGA Course Consulting Service.

Brian Whitlark is a senior consulting agronomist in the West Region.