June 2019 Vol. 27, No. 2

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New cultivars selected for roadside turfgrass

turfgrass sign

Researchers used digital imaging to examine green cover
levels during salt and heat trials and after ice trials.

For nearly a decade, University of Minnesota researchers have been working to improve the health and performance of roadside turfgrasses in Minnesota, focusing mainly on salt tolerance and watering needs for select turfgrass species. In their latest project, sponsored by MnDOT and the LRRB, the researchers focused on identifying grasses that can perform best in the face of three significant stressors: salt, heat, and ice.

The researchers, led by Professor Eric Watkins of the Department of Horticultural Science, found that a mixture of turfgrass varieties and species will likely be the best solution for year-round use in Minnesota, as no one cultivar performed well in every trial.

  • Salt stress. Tall fescue and perennial ryegrass sustained the highest percent green cover and lowest electrolyte leakage throughout the salt stress trials. Alkaligrass, considered salt tolerant, did not perform significantly better than other grasses. Only tall fescue emerged as a salt-resistant turfgrass option, though this cultivar is vulnerable to ice cover.
  • Heat stress. Performance varied significantly within species, suggesting a potential for breeding improvements. Some species performed poorly under heat but recovered well when returned to normal conditions. Researchers recommended Canada and Kentucky bluegrasses, tall fescue, strong creeping red fescue, and slender creeping red fescue as heat-resistant turfgrass cultivars.
  • Ice stress. Tall fescue performed best in image and color analysis. Field observations and previous study, however, suggest that tall fescue performs poorly under ice cover. Warm season grasses died during the control cold storage. Researchers concluded that the ice trial did not properly simulate field ice cover conditions.

"We need to use the best genetics
along the roadside as possible.
Using the right variety of turfgrasses
improves the chances of success and
can save a lot of money for public

—Eric Watkins

Based on the study results, the team developed recommendations for MnDOT guidelines on salt-and heat-resistant turfgrasses; tests related to ice-resistant cultivars were inconclusive.

The team also recommended a mixture of cultivars for field studies, which began last year as part of a second phase of the research. In phase two, researchers are using a mixture of six species selected from this study: Kentucky bluegrass, slender creeping red fescue, hard fescue, buffalograss, alkaligrass, and tall fescue. Mixtures are being planted in different combinations on roadsides for evaluation. In the meantime, MnDOT is adjusting its seed mixture recommendations for use based on the results of this and other studies.

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