By Christine Menapace
From the February 2024 Issue
The transition zone has always been one of the most challenging places to grow and maintain high quality turfgrass. “Transition zones are areas where neither cool- nor warm-season grasses are completely adapted,” describes the National Cooperative Extension Foundation. Even the exact location of the zone seems to differ slightly from source to source. Yet, as most know, it’s generally a band between northern and southern climates where both cool and warm season grasses are grown depending on the micro-climate. LawnStarter defines the transition zone as including parts of 24 states. That’s a lot of turfgrass acreage. Generally, cool season grasses such as tall fescues, fine fescues, perennial ryegrass, and Kentucky bluegrass are planted in the northern zone. Warm season grasses used typically include Bermudagrass, centipedegrass, and zoysiagrass.
Yet with today’s combination of hotter summers, fluctuating rainfall, as well as improved turfgrass varieties, are grass choices transitioning within the transition zone? What about other challenges?
Turf spoke with two turfgrass professors within the transition zone for their perspective. Dr. Michael Goatley serves as the Turfgrass Extension Specialist in the School of Plant and Environmental Sciences with Virginia Tech. Dr. Grady Miller is an ENVU Distinguished Professor of Sustainability & Extension Specialist in Turfgrass Management at North Carolina State University (NCSU).
Q & A With Professors
Do you have a turfgrass recommendation you feel performs best in typical residential yards in your area? Why?
Goatley: In a transition zone state such as Virginia the ‘best’ choice remains debatable given the differences in climate and soils in the state. Turf-type tall fescue is the number one grass for residential yards, but there are definitely situations (especially in the warmest regions of Virginia) where a warm-season grass would be a better choice.
Miller: Yes, but it depends where in North Carolina (coastal, piedmont, mountain climates). Further information can found in “Carolina Lawns: A Guide to Maintaining Quality Turf in the Landscape.
Do you see turfgrass selections changing in the transition zone either currently or in the near future? Are regions for cool season and warm season grasses shifting at all? If so, where?
Goatley: Over my career there has been much more emphasis placed on turf-type tall fescue in Virginia than Kentucky bluegrass. I think that is due to improved genetics in the breeding programs in terms of overall performance and quality of the tall fescue, as well as overall lower inputs for the tall fescue compared to the bluegrass.
The Winter dormancy factor (and loss of green color) for warm-season grasses continues to be a primary reason cited by homeowners for not planting a warm-season grass, as well as the invasiveness of fast growing grasses like bermudagrass.
Although it also has the dormancy issue, I anticipate that the continued developments of improved zoysiagrasses will lead to an expansion of this species in Virginia. But at this time, the increase in acreage is slow because of the high cost/time required of establishing zoysiagrasses, either vegetatively or from seed.
Miller: It has changed since 2007-2008 (droughts). We began moving away from predominantly cool-season grasses towards more warm-season — at least in the piedmont of North Carolina.
Water crisis in many areas is affecting turfgrass. Do you have any thoughts on the future of turfgrass (or types) in these areas?
Goatley: The mid-Atlantic typically gets enough natural moisture to minimize these concerns, but even in 2023 we have had persistent drought in central and northern Virginia, thus reminding everyone of the importance of choosing grasses that require less water.
Virginia Tech is pleased to partner with the Turfgrass Water Conservation Alliance. Their recommendations for low-input turfgrass species/varieties are also found on our annual Virginia Turfgrass Variety Recommendation List.
Miller: We have already seen greater use/acceptance of warm-season grasses, especially Bermudagrass in new construction that has no shade, zoysiagrasses, and even an increased interest in St. Augustine-grass in the more eastern portion of the state. Centipedegrass use has remained strong in areas where it’s well-adapted.
Beyond climate issues, what are the main challenges you see affecting turfgrass today (herbicide resistance? pests?) and what are some of the proposed solutions?
Goatley: Some of our biggest pest problems are the management of perennial grassy weeds in perennial turfgrass systems (i.e. Bermudagrass, dallisgrass, and other Paspalums, roughstalk bluegrass, etc.) We have made very significant improvements in programming for Bermudagrass management (“control” is too strong a word) in cool-season grasses, but the other grasses and their management in other use situations remains very difficult. Continued evaluation of new chemistry and use will obviously help, but also continued education on balancing the expectations of property owners regarding “pest free” lawns and the importance of the basics (soil health, selecting the right grass, responsible mowing, and fertility programming etc.) will go a long way towards reducing pest pressure in general.
Miller: There’s still a ways to go to get acceptance of warm-season grasses for those customers that really want green grass year-round. I do not see herbicide resistance as being as big a deal in landscape at this time as with golf/sports turfgrass areas. We do have some new emerging pests (insects, nematodes, mites, and weeds) that have brought some challenges to North Carolina.
Is there a turfgrass variety or area of research you are particularly excited about?
Goatley: Every species has something really interesting going on as breeding programs evolve: better water use efficiency for all species, finer textured and creeping tall fescues, lower input and faster germinating Kentucky bluegrasses, cold tolerant and finer textured Bermudagrasses, simply expanded availability of improved zoysiagrass cultivars and species… those all come to mind.
Miller: Yes. NCSU has two new grasses recently released, (Lobo™ Zoysia- grass in 2021 and Sola™ St. Augustinegrass in 2022, both exclusively licensed by Sod Solutions) and so that is pretty exciting. But all our research, including colleagues’, is interesting to me.
Turfgrass is facing criticism for creating monoculture and limited pollinator support. Yet there is research on “pollinator sod” and “refuge” lawns. If you are involved in that, could you tell us more?
Goatley: My colleague, Dr. Shawn Askew, and I initiated a trial on pollinator sod several years ago and it opened our eyes to the difficulty of what seemed like, on paper, a very promising opportunity for promoting an expansion of pollinator habitat. However, since many of the best and most attractive pollinator plants have taproots, it limits traditional sod harvesting strategies for cutting and transplanting.
Further concepts on our end involve pollinator sod grown on plastic (similar to thick-cut sod programs being used on sports fields), but this strategy would obviously come with a very high price tag. We have made a harvestable sod composed primarily of yarrow and fine fescue, but there’s not a lot of diversity in that end product either.
One of the very interesting things that Dr. Askew did — building upon a concept from Dr. Mike Richardson’s program with zoysiagrass at the University of Arkansas — was to plant Spring blooming bulbs under tall fescue and fine fescue sod to provide visual ‘interest’ in a lawn as it wakes and have it serve pollinator needs at a time when there isn’t a lot of maintenance required for the lawn. After six years, there are a few crocus species that seem to be surviving and expanding underneath cool-season sod. But many species of irises and daffodils are not necessarily competing.
Transforming Turf
TruNorth Landscape earned Gold in Residential Lawn Care from NALP for bringing the green back to this grass. Read more…
Transforming TurfFeel free to add other info/perspectives helpful to Turf readers.
Goatley: The expectation of the client for “immediate” responses in product availability and performance, information, etc. is only growing in an age filled with such readily available and powerful technology. This presents a lot of challenges BUT also opportunities for the brightest in the Green Industry to educate and serve a clientele with prompt, science-based information strategies, products, and services.
There will always be the necessity for patience in achieving/ delivering the best lawn and landscape possible, but those that will be successful are going to figure out the best way to deliver science-based information in an easily understandable way. My experience has been that most customers are willing to pay premium prices but they do have expectations of premium performance. It is an era of great challenges AND opportunities in the Green Industry.
Do you have a comment? Share your thoughts in the Comments section below, or send an e-mail to the Editor at cmenapace@groupc.com.
