Shade doesn’t dim appeal of zoysiagrass on greens

Superintendents looking for a shade-friendly, heat-tolerant grass may have luck replacing bentgrass greens with zoysiagrass strains.


Aerial view of Ghost Creek golf course
During an interactive facility learning tour at last month’s GCSAA Conference and Trade Show in Orlando, John Sorochan, Ph.D., right, outlines some of the benefits of using zoysiagrass for putting greens in the transition zone. Photo by Tyler Stover

As golf course superintendents in the transition zone considered or implemented changing from bentgrass to bermudagrass to improve heat tolerance, the drawbacks of bermudagrass, such as low shade tolerance, soon became apparent.

“Golf course superintendents started to find they had a lot more shade issues on their golf courses than they realized,” said John Sorochan, Ph.D., turfgrass professor at the University of Tennessee-Knoxville, during last month’s GCSAA Conference and Trade Show interactive facility learning tour at Marriott’s Grande Vista Golf Club in Orlando. The tour was one of eight hands-on learning opportunities offered during the annual conference.

Sorochan said one solution to too much shade is to cut down trees, but that approach can be a challenge, especially if a tree shading a green or fairway isn’t on the golf course’s property or the tree was planted in memory of a deceased club member.

An alternative is to replace the bermudagrass with zoysiagrass, which has much better shade tolerance, especially Zoysia matrella. Sorochan noted that 13 species of zoysiagrass have been identified.

Researchers are now interested in exploring how zoysiagrasses will perform on a putting green.

“We wanted to look at whether they can tolerate green height,” Sorochan said. “Can we get the speeds, the trueness and the rolls out of them?”

Some new varieties that have been studied at the University of Tennessee — Lazer, Prizm and M85 — have shown exceptional green speeds, Sorochan said. Management techniques for the varieties were discussed, compared to bentgrasses and bermudagrasses, with high wear tolerance and few ball marks found to be especially true for Lazer.

Another difference is that zoysiagrass rhizomes — the subterranean plant stem that sends out roots and shoots from its nodes — will generate leaves that rise at 90 degrees from the soil, in contrast with bermudagrass rhizomes that generate leaves parallel to the surface. 

Those bermudagrass leaves can create a grain that often points in the direction of water, which may affect consistency of the green. That can mean superintendents must spend more resources in vertical mowing and topdressing than with zoysiagrass greens.

Sorochan noted that zoysiagrass also can be planted to the edge of the green and will not encroach into neighboring areas, such as bunkers or fairways, saving the time needed to edge bermudagrass greens. Zoysiagrass also does not need to be covered in moderately cold weather, enduring much cooler temperatures than bermudagrass, and will maintain its green color when kept at greens height, eliminating the need to paint greens during winter months.

Low nitrogen needs also are a benefit of going to zoysiagrass.

“We’re looking at between 2 and 3 pounds of nitrogen per year per thousand square feet,” Sorochan said, “so not very much nitrogen at all” during the transition zone growing season, from April to September.

He said mowing zoysiagrass also is more manageable.

“Even in the summer, they’re not growing like crazy. You’re not filling up your buckets like you are with bermudagrass,” he said. “We kind of manage them like we manage bentgrass in the transition zone. We can even mow every other day, but we roll every day.”

Sorochan said rolling every day helps keep green speeds fast and consistent.

“Even if you mow and roll, the speeds from an hour after mowing till the next day when you come back and mow again are pretty much the same,” he said. “They don’t change that much, whereas with bermudagrass greens, you could lose a foot (in rolling distance) by the end of the day because it’s growing so much.”

Other stations at the learning tour included demonstrations by Toro that covered new sprinkler technology, as well as an update on a triplex autonomous fairway mower. Matt Morrison, Grande Vista’s GCSAA Class A director of grounds and 12-year association member, and Cornell University turfgrass professor Frank Rossi, Ph.D., a 32-year GCSAA educator member, outlined the recent putting green upgrades at the course, removing 25-year-old TifEagle bermudagrass and replacing it with — of course — zoysiagrass.

Darrell J. Pehr is GCM’s science editor.