New grass, new problems

Features - Disease Management

Superintendents caught napping following a conversion from bentgrass to ultradwarf Bermudagrass greens might be surprised by what they see.

Subscribe
January 14, 2015
Rob Thomas

Golf courses across the southern United States have been making the switch from bentgrass greens for Bermudagrass. While the latter may be less impacted by heat, superintendents are now facing the issue of unfamiliar diseases.

Dr. Lane Tredway, senior technical field representative for Syngnenta, is receiving a significant increase in questions about diseases on Bermudagrass greens. Ten years ago, whenever he gave a talk, the majority of questions were about bentgrass greens. Now, 80 percent of the questions he receives are about Bermudagrass greens. Because this has been such a sizable shift and happened so quickly, Tredway said the transition could be called a “revolution.”

Why the dramatic shift?

“It all boils down to playing conditions,” Tredway says. “When properly managed, the ultradwarf Bermudagrasses provide playability that equals or surpasses creeping bentgrass in many locations. Because Bermudagrass is so much more tolerant of heat and mechanical stresses, superintendents can focus less on summer survival and more on creating an outstanding putting surface.”

Because of the relative quickness in the rise of Bermudagrass popularity, there is not a wealth of historical research in certain geographic regions, according to Tredway. Both Syngenta – and the industry as a whole – are working to support the current needs of superintendents with this transition. Thus far, more issues have been found with newer varieties than their predecessors.

“Unlike older Bermudagrass varieties, which had relatively few disease problems, the ultradwarf Bermudagrasses are susceptible to a variety of fungal diseases,” Tredway says. “Spring dead spot, Rhizoctonia zeae and fairy ring are the most difficult to manage and have become chronic problems in many locations. Leaf spot, Pythium blight, Microdochium patch and cream leaf blight are also common. These diseases attack the ultradwarfs during the fall, winter and spring when they are dormant or semi-dormant. Although these diseases are not the most destructive, they hit at a time when the turf is growing very slowly, so recovery from any damage can take a long time.”

Pests also present new challenges.

“Because they are more shallow-rooted, the ultradwarf Bermudagrasses tend to be more susceptible to nematodes than creeping bentgrass,” Tredway says. “The ultradwarf movement makes it even more important that we develop new tools for nematode management on golf courses.”

Charlie Costello, superintendent and facilities manager at Phoenix (Ariz.) Country Club, says his club did a major renovation in the summer of 2002, which included the removal of bentgrass greens and changing to TifEagle Bermudagrass. Though he didn’t arrive until 2006, one of his first responsibilities was to correct some mistakes his predecessor made while overseeding the previous year.

“My corrective measure was a ‘no-till renovation’ with Champion ultradwarf Bermudagrass.” Costello says. “I chose Champion because of Scott Kraut, the superintendent at Superstition Mountain. I always felt Scott’s greens were some of the best I had ever played on.”

Costello notes the new ultradwarfs are popular for a number of reasons: No-till conversions are quick and rarely expensive; density of surface is “incredible;” and the non-overseeded surface is a “wonderful putting surface.”

That said, he has dealt with diseases such as Bermudagrass decline, Gaeumannomyces graminis var. graminis, Bipolaris leaf blotch and Pythium blight. A seminar provided Costello with the clarity he needed in maintaining his greens, which are generally affected mostly during the fall and winter.

“Until hearing Dr. Phil Harmon of University of Florida at a seminar in Phoenix, I was guessing ... treating the disease on a curative basis,” he says. “After hearing his talk about these diseases, I immediately changed to a preventative mentality. This is my first winter season since hearing ‘Dr. Phil,’ however, up to this point we have not seen disease. This is very exciting because the diseases normally flare up greatly in October.”

Dale Samar, general manager of Rancho Manana Golf Club in the Phoenix area, says his course switched from bentgrass to Bermudagrass because the team felt bentgrass greens required much more maintenance and also didn’t handle the volume of rounds the course received annually.

“In the Southwest, I think Bermuda greens have been growing in popularity over bentgrass for that same reasons we switched, along with now there is such a greater variety of Bermudagrasses to choose from, which make better options to fit any particular southern climate,” Samar says. “Bent greens in the desert areas of the Southwest require a strict watering schedule throughout the day during the summer months – usually by hand – as well as much more disease monitoring/management during these periods of hot, humid weather. While Bermudagrasses can be susceptible to some of the same diseases as bentgrasses, we have been lucky to avoid most, as Bermudagrasses are quite a bit more disease resistant in our southwestern climate.”

Green Meadow Country Club in Alcoa, Tenn., converted to Bermudagrass in the summer of 2013. According to superintendent Brad Fox, summer stress in the Southeast and accumulating Poa annua in existing greens made maintaining bentgrass tough at an acceptable level. Plus, Bermudagrass provided excellent putting surfaces during peak golf times in the summer. His team has quickly learned what diseases their greens are most susceptible to.

“For us, it's bipolaris leaf spot during extended periods of cloudy and rainy days without sunshine,” Fox says. “Another disease we treat for is Rhizoctonia Zeae ‘mini ring,’ which can pop up during the hot and humid summer conditions. Others include spring dead spot and fairy ring. These two diseases are pretreated for in the spring and fall when soil temps are in the mid-50s to low-60s.”

Careful daily monitoring of the greens surfaces and watching the weather closely, especially during the shoulder months, helps Fox stay on top of these culprits. “Most all of the diseases we spray for can be managed preventatively if you keep a watchful eye on the weather,” he says.

While a lab isn’t always needed to determine what disease is present, Tredway says looks can be misleading. “Spring dead spot, Rhizoctonia zeae and fairy ring can often be diagnosed on-site based on their characteristic symptoms,” he says. “However, these diseases can sometimes cause unusual symptoms and fool even the most experienced superintendent or turf pathologist. A laboratory diagnosis is always a good idea, since the curative options for these diseases can be quite expensive.

“Leaf spot and Pythium blight are frequently confused for one another; they develop under the same conditions and their above-ground symptoms can be very similar,” he adds. “Close examination of the affected leaves with a magnifying glass or small microscope can help to distinguish these. Leaf spot causes distinct tan spots on affected leaves, whereas Pythium blight causes purplish-black greasy dieback.”

Samar’s maintenance staff can generally first identify diseases by sight, but if needed they can have soil samples taken to further investigate. “Healthy turf and roots are one of the best ways to prevent disease as well as not overwatering,” he says. “Overwatering can really cause problems during both cooler and warmer times of year.”

Strategies have changed on the best way to treat Bermudagrass greens as their popularity has grown, Tredway says. “Despite initial beliefs that the ultradwarf Bermudagrasses required minimal fungicide inputs, it is becoming more apparent that a season-long preventative program is necessary,” Tredway says. “Rhizoctonia zeae, in particular, is very difficult to manage and requires tank mixtures and rotations of multiple fungicide chemistries. Many of these fungicides applications will also help to prevent fairy ring. Spring dead spot must also be prevented, with fall application of fungicides prior to winter dormancy.

“With Rubigan no longer in production, superintendents will soon need an effective alternative for spring dead spot control,” he adds. “Headway fungicide has shown excellent spring dead spot control and safety to the ultradwarf Bermudagrasses, and also provides broad spectrum control of other diseases such as Rhizoctonia zeae, fairy ring, leaf spot and Microdochium patch.”

For southern courses considering making the switch to Bermudagrass, Costello believes it’s an easy decision. “If you are in the South with Bermuda greens, to me it is a no-brainer,” he says. “You will love overseeding your golf course and not having to worry about overseeding your greens. There is nothing better at overseed time of the year, opening your golf course and having greens roll as fast as you want them to be. So while everyone is wet, growing in their ryegrass and Poa trivialis, I think it is a great advantage to have nice, firm and fast greens from opening day. I believe it dampens the sting of wet conditions, cart paths only, etc.”

Samar adds the human aspect into the discussion. “Any course contemplating switching has to consider not only the agronomic issues but also the wants and desires of the players and/or members,” he says. “Additionally, many climates will require Bermuda greens to be overseeded, as well, which requires the course to be shut down each fall for 12-18 days. Once a decision is made to make the switch, planning is critical, as the sod generally has to be ordered well in advance so the sod farm will have enough available and at the correct height. However, we were able to make the actual change from bent to Bermuda in 19 days, which included striping the bentgrass, laying out the new sod and growing it into a smooth putting surface. It was definitely the right decision for us.”

Fox’s advice comes with a warning. “Do your research,” he says. “It isn't a foolproof grass with less needs. It's a very aggressive grass that must be maintained aggressively to achieve desired results.

“What you may save in summer labor dragging hoses will catch up to you in increased costs in topdressing sand, bedknives and winter help for covering greens,” Fox adds. “Also, learn as much as you can from as many people as possible and adjust how they do things to what your course wants and can do. Overall, switching was the best thing for us and we've found that the rest of the course has improved because of installing these greens. We have more time in the summer for detail work and other projects.”

For Tredway, the decision is much more specific to the course in consideration. “While ultradwarf Bermudagrasses are working well for many courses, they are not for everyone,” he warns. “If the majority of your golf rounds are during the fall, winter and spring when Bermudagrass is dormant or semi-dormant, then creeping bentgrass may still be a better choice. Also, remember that Bermudagrass has very low shade tolerance and also does not perform well in poorly drained greens. If shade and poor drainage are limiting factors for your bentgrass greens, then a conversion to Bermudagrass may actually make the situation worse. Winter covers are essential in climates when low temperatures in the mid-20s or below are expected.”


 

Rob Thomas is a Cleveland-based writer and frequent GCI contributor.