A cooperative research project examines a new method for temperature control on Southern greens.

Steve and Suz Trusty

Researchers from Clemson University teamed up with Wild Wing Plantation for on-course testing of a system for cooling bentgrass greens.

Operating under the philosophy that if you want to see how something really works on a golf course you should try it out on a golf course, researchers and superintendents have teamed up for a joint project that adds on-the-course reality to the testing focus.

David S. Downing II, CGCS and director of golf operations for Wild Wing Plantation in Conway, S.C., along with researchers from Clemson University and the Carolinas Golf Course Superintendents Association (CGCSA) have begun testing a new system for cooling bentgrass greens during hot Southern summers.

"Temperature control on bentgrass greens is essential to their survival in hot weather sites," says Downing, a 19-year GCSAA member. "Summer temperatures in our area of South Carolina can become excessive. Canopy temperatures that reach or exceed 120 degrees Fahrenheit are deadly for the bentgrass greens."

Searching for solutions
Downing was hired to oversee the 1,000 acres of Wild Wing Plantation during the rough-in of Wood Stork, the facility's first course, which opened in the fall of 1991. Three other courses have been added to the facility: Hummingbird opened in spring 1992, Avocet opened in spring 1993 and the Falcon opened in fall 1994.

The greens on all four courses are currently planted to Pennlinks. Obviously, such factors as the angle of the green, the degree of direct sunlight and shade and the amount of air movement influence the heat-up time for each green, so temperatures vary.

"Our superintendents and assistant superintendents carry hand-held infrared thermometers to monitor the canopy temperatures on the greens," Downing says. "When the temperatures approach 110 degrees -- our predetermined threshold of danger -- we take action."

David Downing II, CGCS at Wild Wing, has been searching for a solution to control temperatures that he says can exceed 120 degrees F on his bentgrass greens.

Syringing is most commonly used to cool down greens before damage occurs. "The negative of syringing is that it is applies more water to the surface of the green," Downing says. "We want to keep our soils and surfaces as dry as possible to reduce our incidences of disease. And, even following a heavy rainfall, we may need to cool down the plant so it will survive."

Always an innovator, Downing has been experimenting with alternate cool-down methods since he arrived at Wild Wing. He's achieved good results using a tractor-mounted blower to reduce the temperature by as much as 20 degrees. The tractor is driven around the green up to three times to achieve this temperature drop, or in severe situations, the tractor is parked at the green with the blower running.

"The blower method is a time-intensive procedure, and the number of greens that can be treated are limited to available equipment," he explains. "We're still looking for a better method of control."

Downing first heard of "a unit that blows air into greens" through existing drainage about three years ago through Wild Wing's management company, Western Golf Properties. He saw the unit while visiting superintendent Marsh Benson at Augusta National, and then he contacted Sub-Air.

"We learned that basically, a Sub-Air system can either pull out excess water from the green or blow in air," Downing says. "We leased two permanent and eight portable Sub-Air systems through John Deere Credit. For the last year, we've been experimenting with them on some of our most susceptible greens. We've installed one of the permanent systems on the 12th and 17th greens on the Falcon and one on the Wood Stork course on the 11th and 14th greens. The eight portable systems are moved around the courses to various problem greens."

The drain lines on the research green were "rocked in" by hand.

The idea is born
The idea for a joint research project was born when Wild Wing hosted a demonstration day attended by Bruce Martin, Ph.D., associate professor of plant pathology and physiology from Clemson, as well as several other Clemson staff members.

Because the combination of bentgrass and high temperatures is such a widespread problem, CGCSA was very interested in experimentation under actual course conditions.

Martin initiated the plan because the university was looking for testing on a regular green that would get nearly constant use by golfers, instead of on an isolated test plot on the university campus. Jim Camberato, Ph.D., associate professor of soils, and Roy Dodd, Ph.D., associate professor of agricultural and biological engineering, are partners in the project along with Martin. This team brings to the project combined expertise in plant pathology, turf management, soils, plant physiology and engineering.

Clemson established the specific elements of the testing and monitors the results. CGCSA assisted with bringing in contributions to help finance the project.

Wild Wing had a good site for the research green -- a spot with poor air movement and a fair amount of shade. "We could also put plenty of traffic on it and were willing to let them rebuild the green to the size they wanted." Downing adds.

Industry support
A unique element of this joint project was the donation factor. So many contributors "chipped in" that a much smaller cash outlay was needed to build the green.

David Montgomery and his MLI construction company, which has been involved with all four of Wild Wing's courses, constructed the green. Downing notes that Montgomery's expertise in shaping, draining greens and his instrumentation on the air pipes were critical to the green being built correctly.

Black Creek Sand donated the mix. Vulcan Materials donated the gravel. All the seed companies supplied the seed for the project through Clemson. Frankie Verren (a local supplier) supplied all the drainage pipe. Goldkist supplied the fertilizer. The Horry Telephone Cooperative brought in a line so Clemson could hook up a computer and modem to control the system. And Sub-Air supplied the system. Cylex of Tempe, Ariz., will be supplying a sign to let the public know what is happening underfoot.

"The cooperation was wonderful," Downing says. "We asked and they gave. No one was pressured to do it, but everyone contacted wanted to see it happen. It was interesting to see it all fit together. So, with all the donations, a $70,000 project was completed with approximately a $30,000 cash outlay."

Making it happen
Construction of the 12,000-square-foot chipping green began in late February 1997 following USGA greens recommendations. The green is divided into four quadrants so any one or any combination of the quadrants can be treated with Sub-Air. Plastic dividers run from the edge through the center, in two directions, establishing four individual sections.

Air is supplied to each section through 8- and 10-inch PVC pipe. Two extra connectors were installed to allow a portable unit to be attached if more air is desired. Conduit runs beneath each plot so thermocouples can be inserted to take temperature and gas readings in the future. Four different varieties of bentgrass were used: Penncross, Pennlinks, Crenshaw and A-1. Every grass is in every quadrant.

"A lot of courses here still have Penncross on USGA spec greens," Downing notes. "Crenshaw is one of the newer varieties that is used quite a bit on area courses, and since we have Pennlinks here, we wanted to test it. In our own testing on several of the newer varieties, the A-1 plot had performed best. It has also done well in Clemson's test plots, so that's why it was chosen. If this research can eliminate the need to re-grass greens, it could save us all money in the long run."

The green was seeded at the end of April. "We've done spring seedings of bentgrass in the Conway-Myrtle Beach area in the past and it has failed miserably," Downing says. "With the system in place, the new grass not only survived the summer, but was established sufficiently to allow us to open the green to play in August -- the middle of the summer -- and to stand up to that use.

"We did have one quadrant shut off for a short period during the grow-in. During the third week of June, hot weather moved in and the bentgrass in that quadrant was visibly weakened. Alan Penland, superintendent of the Avocet Course during the construction of the project, went into the vault and opened up the fourth quadrant so it could get a treatment. The grass snapped back and has done well ever since."

Initially the system was in operation 24 hours a day. Clemson researchers are in the process of designing a computerized system that they can control from the Pee Dee Research and Education Center in Florence. They will then make all the decisions about the Sub-Air system, and Downing's staff will handle the other standard maintenance procedures.

Researchers also plan to use infrared photography to monitor the canopy temperature uniformity. In addition, they've installed rhizotrons so they can conduct rooting studies of each plot.

Project goals
Downing notes there will be six or seven years of research tied into this green, and all of it will be conducted under playing conditions. One key aspect of the testing will be identifying why the system works.

"Is it the cooling? Is it the ability to dry the soil a little bit by taking the excess water out? Is it strictly the gas exchange that allows the roots to have better oxygen around them at key times during the year? Or is it a combination of all these factors? We want to pinpoint that," he says.

"Other areas of research will center on such operational details as the optimum period to run the system during specific conditions," he adds. "Costs of running the system full time are approximately $100 to $150 a month. If, in the future, it can save some syringing, use of top-side blowers or other labor-intensive procedures, that's a pretty good investment. Some testing results provided by Sub-Air show the air in a green can be completely exchanged in approximately an hour. They think that effect can last about three days. That's one of the areas, one of the many variables, we'll be testing. We need to determine the most effective and efficient way to use it to produce the best possible results.”

This turf plug sample pulled from the chipping green shows the root development.

Interest in the joint research project is spreading beyond the Carolinas. It was a topic of discussion during the 11th annual International John Deere Team Championship Golf Tournament held Nov. 8-9, 1997 at Wild Wing's Avocet course. The event brings together competing teams composed of a club's golf professional, superintendent, club manager and club president (or two other members of the top management team), and its local John Deere distributor. It provided a great opportunity for courses' management teams to see the system in operation and ask questions related to their own course operations.

In addition to the Sub-Air project, Ted Whitwell, professor of horticulture, did some bentgrass encroachment herbicide testing. He sprayed the edges of both sides of the greens with different herbicides to determine their effectiveness in knocking back the bermudagrass. The different varieties of bentgrass allowed him to better gauge their reactions to each of the products tested. Clemson plans to tie in other similar types of research.

Because the practical aspects of this cooperative research project have been matched by positive responses from contributors, by the commitment of Clemson University and Wild Wing personnel, and by the enthusiasm of superintendents, it’s definitely on course to produce useful results.

Steve and Suz Trusty own and operate Trusty & Associates, a Council Bluffs, Iowa-based consulting firm that caters to the horticultural and turfgrass professions.