Tall Fescue, KY bluegrass, KY X TX bluegrass Cultivar Selection and Disease Management
Dr. Dennis Martin, Dr. Andrea Payne Connally, and Mr. David Gerken of OSU, Stillwater and Dr. Nick Boerman, USDA-ARS, Woodward.
Introduction
The cool-season perennial introduced grasses tall fescue (Schedonorus arundinaceus, formerly Festuca arundinacea) and Kentucky bluegrass (Poa pratensis) are frequently used as turfgrasses in Oklahoma. In recent decades, improved cultivars of the interspecific hybrids between Kentucky bluegrass and the native perennial Texas bluegrass (Poa arachnifera) have been used.
The turfgrass program at OSU at Stillwater is hosting the 2017 National Turfgrass Evaluation (NTEP) Kentucky bluegrass trial (Block 3, see plot plan), the 2018 NTEP Tall fescue trial (Block 1 & 2), and a hybrid bluegrass trial containing experimental materials from the breeding and genetics program of the USDA-ARS Southern Plains Station at Woodward, OK.
Methods
2017 NTEP Kentucky bluegrass trial – The OSU at Stillwater test site is one of 23 sites testing 89 entries in the 2017 NTEP Kentucky bluegrass trial. The trial was planted in spring of 2018, is fertilized with approximately 4 pounds of nitrogen per 1,000 sq. ft. per year. Phosphorus fertilizations are variable and based on soil testing to keep the Mehlich III soil test phosphorus index at 65 lbs per acre or slightly greater. Likewise, our annual potassium additions are made based on soil testing to keep the Mehlich III soil test potassium index at 250 or slightly above. The trial is mowed at 2.5 inches twice per week and watered as needed to keep the trial from substantial wilting. Whereas actual turf management sites of cool-season grasses may be reseeded/interseeded each year to increase density, the trials discussed at this tour stop were seeded initially with no additional seed added thereafter.
2018 NTEP Tall fescue trial – The OSU at Stillwater test site is one of 28 sites testing 132 entries in the 2018 NTEP Tall fescue trial. The trial was planted in 2018 and is managed as described for the 2017 Kentucky bluegrass trial with identical data collection protocol.
2018 USDA Hybrid bluegrass trial – We planted three replications of seventeen experimental entries of hybrid bluegrasses in May of 2018. This trial is managed as described for the 2017 Kentucky bluegrass trial and the 2018 NTEP Tall fescue trial with identical data collection protocol.
The three trials described at this tour stop are evaluated for percent living cover, genetic color, quality, texture, density, spring greenup, and resistance to various diseases as opportunities present. Data from the two NTEP trials are submitted to the National Turfgrass Evaluation Program each year with NTEP posting analyzed data from the prior year. As the USDA hybrid bluegrass trial involves experimental lines the OSU program makes the data available to the USDA-ARS breeder/geneticist managing the hybrid bluegrass development program for their decision making.
Results
The three trials discussed at this tour stop are ongoing and data collected from these trials is voluminous. We encourage interested parties to view data from this and prior Kentucky bluegrass trials at https://ntep.org/reports/kb17/kb17_21-5/kb17_21-5.htm with tall fescue trial data analyzed and available for viewing at https://ntep.org/tf.htm.
General Suggestions
Tall fescues are challenged in Oklahoma by high temperatures, heavy shade, drought, white grubs as well as fall army worms, large brown patch and pythium blight among other diseases. Kentucky bluegrasses are challenged in Oklahoma by high temperatures, heavy shade, drought, white grubs as well as fall army worms, summer patch, dollarspot, leaf and crown rusts and various leaf spot and melting out diseases. In general it is suggested that tall fescues and Kentucky bluegrasses be mixed at approximately a 95:5 % weight:weight seed ratio tall fescue:Kentucky bluegrass. Mixing results in increased biodiversity and may help reduce likelihood of complete stand loss by devastating diseases. Exact ratios of the species used will vary based on seed size and aggressiveness of individual cultivars and desired outcomes. Under ideal conditions, consumers are encouraged to pick two or more excellent performing tall fescues and mix with two or more outstanding Kentucky bluegrasses. In general, consumers are often unable to pick individual cultivars for their own mixing but instead can choose among mixes available from various vendors. Consumers can use the legal seed trade label and using the cultivar names found on the seed tags review performance of those cultivars are the NTEP website. Consumers are encouraged to pick certified pedigree seed and try to find seed mixes with as low of “weed seed” and especially “other crop” components as is possible. Fall seeding is preferable over spring seeding. Reseed in fall only if necessary. Fertility and watering programs will vary based on region of the state, exposure of the site, individual weather patterns within the year and desired appearance/utility of the turf. In general consumers are encouraged to use as minimal of nitrogen and water input programs as feasible to achieve goals and to maintained turf in a hardy condition. As tall fescue and Kentucky bluegrass are stressed by heat and drought more easily than many warm-season grasses, consumers should consider limiting use of these species when warm-season grasses are better adapted to the site.