Performance of Kentucky Bluegrass Cultivars in Michigan: 2001-2005 (E2924)

Kentucky bluegrass is the most widely used turfgrass in Michigan. It is used in home lawns, institutional grounds, parks and athletic fields. The species is persistent and attractive and has a medium to fine leaf texture and medium to dark green color.

Kentucky bluegrass is the most widely used turfgrass in Michigan. It is used in home lawns, institutional grounds, parks and athletic fields. The species is persistent and attractive and has a medium to fine leaf texture and medium to dark green color when properly fertilized. Plants produce extensive underground stems, called rhizomes, which provide good sod-forming characteristics and recuperative potential superior to that of most other turfgrasses. It is cold- and wear-tolerant but has only moderate heat and drought tolerance. Optimum growth occurs during the spring and fall, but without irrigation it will likely turn dormant during hot, dry periods in the summer. Kentucky bluegrass will recover quickly with the advent of cooler temperatures and adequate soil moisture.

Plants perform best when grown on well-drained soils in open, sunny areas. This grass species does not tolerate poorly drained soils or extensive shade. Kentucky bluegrass generally requires more nitrogen (N) fertilizer than other cool-season grasses and tends to produce a significant amount of thatch. Mowing height should be maintained at 2.5 to 4 inches except during hot, humid conditions, when the mowing height should be raised to 3 to 5 inches. It is difficult to maintain at 2 to 3 inches without irrigation. When planted from seed, Kentucky bluegrass requires up to two weeks for seed emergence.

The National Turfgrass Evaluation Program (NTEP) Kentucky bluegrass test was established in September 2000 at the Hancock Turfgrass Research Center at Michigan State University. The test comprised 172 commercial cultivars (see table). The trial was mowed three times per week at a height of 2.5 inches. Three to 4 pounds of N per 1,000 square feet were applied each growing season. Plants were irrigated whenever necessary to prevent wilting.

The plots were visually evaluated once per month during the growing season for turfgrass quality and other parameters. “Quality” means the overall appearance of the turf plots. Components include density, texture, uniformity, color, and freedom from disease and insect damage. Quality was rated using a scale of 1 to 9, where 9 equals the highest quality. Entries are listed in order of highest seasonal average quality for 2001, 2002, 2003, 2004 and 2005 to lowest seasonal average quality for the five years combined.

Percent living ground cover in the summer was rated on the basis of surface area covered by the originally planted species. It is used to express damage caused by disease, insects, weed encroachment or environmental stress. Percent living ground cover is often measured in the spring, summer and fall and rated as a percentage. The summer allows us to track the turfgrass response to various stresses during the growing season. For comparison, average turfgrass quality and percent living ground cover of Kentucky bluegrass grown at 11 U.S. locations — Illinois, Indiana, Kentucky, Massachusetts, Missouri, Ohio, Oklahoma, Rhode Island, Utah, Washington and Wyoming — are included in the table. Turfgrass quality of Kentucky bluegrass grown under artificial shade at Bowling Green, Ky., was included also (see the table).

Differences between two entries are statistically significant only if the numerical difference between two entries exceeds the LSD value listed in the table. For example, if cultivar ‘Award’ is 0.5 units higher in quality than cultivar ‘Allure’, this difference is significant because the LSD value is smaller (0.4). If the LSD value is greater than the numerical difference between the two cultivars then the difference is not significant. Coefficient of variation indicates the percent variation of the mean. Smaller variation indicates good data validation.

 Few differences in turfgrass quality were found among the Kentucky bluegrass entries in this test during 2001- 05. In spite of differences in growing conditions in 2001, 2002, 2003, 2004 and 2005, the average turfgrass quality of some improved cultivars varied little among seasons. The entries showing the best seasonal average quality over the five-year test period are listed in the table.

For more information, visit: http://www.ntep.org under Michigan State University data.

 

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