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The use of Bermudagrass and zoysiagrass has historically been confined to regions featuring warm climates, specifically below the Mason-Dixon Line. With the impact of climate change, the idea of utilizing strains of Bermudagrass and zoysiagrass in regions farther north is not as far-fetched as it once might have seemed.
Because New Jersey is getting warmer!
Mark LaBarge is a graduate assistant at Rutgers University in the Department of Plant Biology and teaches in the university’s two-year certification program. A Rutgers graduate himself, with a bachelor’s degree in environmental science, he is currently working on his doctorate.
LaBarge is overseeing a study on the viability of zoysiagrass and Bermudagrass in New Jersey and spoke on the topic at the 2024 New Jersey Turfgrass Association’s Turf Expo in Atlantic City. He told Golf Course Industry that the study was prompted by the fact the hardiness zones areas established by United States Department of Agriculture to access the viability of plants in a given area are shifting northward relative to temperature.
Simply put, the average temperature in much of New Jersey has increased over the past three decades or so, which opens the door to species of Bermudagrass and zoysiagrass being utilized on at least some of the state’s golf courses.
LaBarge says the study, which has concluded two growing seasons, was undertaken with an eye on the future.
“With the impact of climate change, especially in the projected heartiness zone; everything is getting warmer,” he says, “and I think sooner rather than later, we’re going to see some kind of transition into the warm season turfgrass species.”
LaBarge says the transition will be possible in part because of advances in turf science.
“I think that’s definitely a big part of it,” he says. “A lot of the breeders at the southern universities, the University of Georgia, the University of Florida, Texas A&M, Oklahoma State, have made really, really impressive advances in their breeding programs focusing on cold tolerance, of both Bermudas and zoysias as well as improved disease resistance. And then they’re able to get into those cultivars really high turf qualities as well which leads to them being more useful further north.
“As a result, I think the sooner we start to evaluate some of the improved varieties here in New Jersey, the more information we have that we can then share with growers here in New Jersey.”
The study featured evaluations of various strains of zoysiagrass and Bermudagrass and how they responded to the rigors of New Jersey’s climate. LaBarge says the results he’s seen to date have largely matched his expectations. “I definitely think a lot of the stuff I was expecting to see happened, especially with Bermudagrasses establishing [quickly],” he says.
But LaBrage encountered some surprises as well. “One of the surprising things was having those zoysiagrasses establish to a 90 to 100 percent cover within one to two growing seasons was kind of a big leap,” he said. “I did not expect that they would be able to establish that fast. For example, DALZ 1701 established within the first growing season and was pretty impressive.”
LaBarge believes that the “line of demarcation” defining where warm-season grasses will survive and thrive will continue to move northward.
“I think that is where it’s going to end up growing,” he says. “As far as the timeline, who’s to say? I think you can still grow cool-season grasses, especially here in New Jersey in the northern part of the state. But, the southern part of the state, the middle part of the state and as you move toward Philadelphia, those regions, as we move forward in time, with the effects of climate change, are going to have to look at some new options.
“And zoysiagrass and Bermudagrass are not the only options. There are improved bentgrass varieties. Ryegrass, I think, might fade out a little bit for fairways with the changing climate but there are certainly a lot of other options besides zoysia and Bermuda. That’s where I think a lot of stuff is going to go, especially in the Mid-Atlantic region.”
LaBarge adds there are mitigating factors that may impact warm-season grasses in northern climates, among them winterkill.
“Winterkill is very important, especially when you think about growing Bermudagrass and zoysia grass,” he says. “Here in New Jersey, it’s probably one of the most mitigating factors to an expansion northward.”
LaBarge notes that winterkill is triggered by low-temperature exposure and soil moisture extremes in either direction. Plants that become dehydrated over the course of the winter are also more susceptible to winterkill. LaBarge cautions that superintendents who introduce warm-season grasses on their properties will have to adjust their management practices.
“There are a lot of pretty significant differences when it comes to managing a warm-season grass versus a cool-season grass,” he says. “There are some similarities, but your management program is definitely going to change.
“I think one of the biggest changes is going to be a decrease in fungicide use and an increase in herbicide use. That’s something to watch out for too because in the South, increases in herbicide use on dormant warm-season grasses to prevent disease encroachment in the winter, has led to a lot of resistance, so I think that is something that is definitely going to need to be addressed to prevent those resistance issues when we start to use these grasses further north.
“And all of your management practices are going to be changing [in terms of] time. A lot more is going to be done in the hottest part of the year when Bermuda and zoysia is the most actively growing. And then the shoulder seasons are going to be tailored towards preventing winterkill and improving fall color retention and spring green up.”
Rick Woelfel is a Philadelphia-based writer and senior Golf Course Industry contributor.
