Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Jared Hoyle / Buffalograss [Buchloe dactyloides (Nutt.) Engelm] is a warm-season turfgrass species that is native to North America and requires minimal maintenance to survive. However, the use of buffalograss on golf courses throughout the transition zone is limited due to its appearance, growth habit, and lack of information available. Buffalograss is more drought tolerant than many other turfgrass species cultivated on golf courses, therefore, its drought resistance can lead to significant water savings. The objectives of these 2014 – 2016 field research studies were to evaluate: 1) buffalograss divot recovery as influenced by nitrogen source and application rate; 2) the influence of nitrogen application rate and simulated golf cart traffic on the wear tolerance of buffalograss; 3) the effect of simulated golf cart traffic on colorant treated buffalograss; and 4) buffalograss recovery from winter trafficking. When compared to untreated turf, divots in buffalograss treated with urea achieved 50% divot recovery 6.3 days faster when 1 lb N/1,000 ft² was applied, which was statistically similar to the 3 lb N/1,000 ft² rate. Applications of a slow-release polymer coated urea did not enhance divot recovery duration when compared to untreated turf. As nitrogen application rate increased in the presence of traffic stress, regardless of traffic rate, the green cover, quality, and color of the turf was enhanced. Percent green cover values for 0, 1, 2, and 3 lb N/1,000 ft² 10 weeks after initiation (WAI), regardless of traffic rate, were 60.2%, 69.0%, 75.5%, and 79.1% respectively. Regardless of nitrogen application rate, buffalograss receiving 16 passes/week of traffic never provided >72% green cover, while buffalograss receiving 0 passes/week had 74% green cover prior to the onset of dormancy. Endurant Premium turfgrass colorant in the presence of wear treatments provided >50% green cover 0 – 5 weeks after treatment in 2014 and 0 – 3 weeks in 2015. In general, as traffic rate increased, turfgrass colorant longevity decreased. Overseeded perennial ryegrass hindered buffalograss recovery after winter trafficking in comparison to untreated turf and colorant applications.

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Dale J. Bremer / Jack Fry / Increasing water scarcity may result in greater irrigation restrictions for turfgrass. Drought tolerance and recovery of Kentucky bluegrasses (Poa. pratensis L.) (KBG) were evaluated during and after 88 and 60 day dry downs in 2010 and 2011, respectively, under a rainout shelter. Changes in green coverage were evaluated with digital images. Green coverage declined slowest during dry downs and increased fastest during recoveries in the cultivar ‘Apollo’, indicating it had superior drought tolerance. Electrolyte leakage, photosynthesis, and leaf water potential were evaluated in 7 KBG cultivars during and after the dry downs. Soil moisture at 5 and 20 cm was measured. There were generally no differences in physiological parameters among cultivars during or after dry down. The highest reduction in soil moisture at 5 and 20 cm was in Apollo, suggesting it had a better developed root system for mining water from the profile during drought. Weed prevention and turfgrass establishment of ‘Legacy’ buffalograss (Buchloe dactyloides [Nutt.] Engelm.) and ‘Chisholm’ zoysiagrass (Zoysia japonica Steud.) grown on turf reinforcement mats (TRM) was evaluated. ‘Chisholm’ zoysiagrass stolons grew under the TRM; as such, use of TRM for this cultivar is not practical. Buffalograss had 90% or greater coverage when established on TRM in 2010 and 65% or greater coverage in 2011; coverage was similar to that in oxadiazon-treated plots at the end of each year. ‘Legacy’ buffalograss plugs were established on TRM over plastic for 3 weeks, stored in TRM under tree shade for 7, 14, or 21 days, and evaluated for establishment after storage. In 2010, plugs on mats stored for 7 days had similar coverage to the control, but in 2011 displayed similar coverage to plugs stored on TRM for 14 or 21 day treatments. Green leaf are index (LAI) is an important indicator of turfgrass performance, but its measurement is time consuming and destructive. Measurements using hyperspectral radiometry were compared with destructive measurements of LAI. Results suggest spectral radiometry has potential to accurately predict LAI. The robustness of prediction models varied over the growing season. Finding one model to predict LAI across and entire growing season still seems unrealistic.

2 pp. / Describes how to select the appropriate lawn mower to properly mow the species of grass at the correct height for high, medium, or low maintenance levels.

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] is a warm season, perennial grass native to the Great Plains from southern Canada to Mexico (Beetle, 1950). This newly developed, low input, turf-type grass is recommended for use on low maintenance sites (Falkenberg-Borland and Butler, 1982; Pozarnsky, 1983; Wu and Harivandi, 1989; Shearman et al., 2005). Recently, the use of buffalograss as a turfgrass has increased due to its drought tolerance, low nutrient requirements, and low growing height (Harivandi and Wu, 1995; Frank et al., 2004). It is an excellent choice in California where water use is limited. Unsightly winter dormancy of buffalograss can be overcome by growing mixtures of buffalograss and fine fescue (Festuca spp.). Overtime species composition can be overtaken by the fine fescue, unintentionally converting the mixed turfgrass stand to a fine fescue monostand (Severmutlu, et al., 2005). Research on buffalograss establishment in fine leaved fescues from seed or by vegetative methods was completed from 2007 to 2009 at the California Polytechnic State University Horticulture Unit in San Luis Obispo, California. Comparisons were made between mixtures of eight cultivars of buffalograss (Prairie, Prestige, UC Verde, 609, Bowie, Cody, Texoka, and Bison) and three fine leaved fescue species [hard fescue (Festuca trachyphylla Thuill.), sheep fescue (Festuca ovina L), and red fescue (Festuca rubra L.)] to determine which combination and establishment strategy provides the highest quality turf for the California central coast region. Evaluations made on buffalograss establishment and competitive ability when grown in pre-existing fine fescue turfgrasses showed seeded cultivars (Bowie, Cody, Texoka, and Bison) were unsuccessfully established (zero percent coverage in two growing seasons), and vegetative cultivar (Prairie, Prestige, 609 and UC Verde) establishment was greatly dependent on the type of cultivar planted. After two growing seasons, buffalograss cultivar UC Verde had the highest establishment rate (38.6 percent living ground cover) and Prestige had the lowest (11.4 percent living ground cover). Results from this study do not recommend establishing seeded buffalograss cultivars into pre-existing fine leaved fescue turfgrass stands. Vegetative buffalograss cultivars can be established into pre-existing fine leaved fescue turfgrass stands; however, this process is too slow for most turfgrass practitioners and is quite unsightly in winter dormancy during the establishment process.