Applied Turfgrass Science最新文献

It has been demonstrated that improved cultivars of seeded common bermudagrass (Cynodon dactylon L. Pers.) can be dormant-seeded during the winter, providing an alternative approach to renovate damaged areas of turf. However, bermudagrass golf courses and athletic fields are often overseeded with a cool-season grass such as perennial ryegrass (Lolium perenne L.) during the dormancy period and the overseeded grass may prevent or delay establishment of dormant-seeded bermudagrass. The objective of this study was to determine if dormant seeding into an overseeded turf could be an effective means of bermudagrass establishment. ‘Riviera’ bermudagrass was seeded into a simulated overseeded turf on three different dates, including March (dormant seeding), April (spring seeding), and June (summer seeding) in 2008 and 2010 at Fayetteville, AR. In addition, five herbicides, including glyphosate, flazasulfuron, foramsulfuron, trifloxysulfuron, pronamide, and an untreated control, were applied to each of those seeding date treatments to alter the competition from the perennial ryegrass. Bermudagrass establishment was enhanced by herbicide application, but less affected by seeding date. Glyphosate applied before seeding provided the highest bermudagrass coverage compared to the other herbicide treatments and sulfonylurea herbicides were also effective at suppressing ryegrass competition compared to pronamide and untreated plots. Establishment of seeded bermudagrass into an overseeded stand of perennial ryegrass turf was improved with herbicide use, regardless of the seeding date. However, there was no advantage to dormant seeding bermudagrass into an overseeded turf.

Field paspalum (Paspalum laeve Michx.) is a problematic, perennial weed in lawns, athletic turf, and golf courses from Texas to New Jersey with similar biology to dallisgrass (Paspalum dilatatum Poir.). The loss of monosodium methanearsonate (MSMA) from the market requires an alternative for field paspalum control in cool-season turf. We evaluated various spring application timings, frequencies, and rates of MSMA or mesotrione applied at two-week intervals in south central Indiana over three years. MSMA applied twice at 2.0 + 2.0 lb/acre (2.25 + 2.25 kg/ha) consistently provided the lowest cover of field paspalum, whereas MSMA applied once at 2.0 lb/acre, mesotrione applied twice at 0.25 + 25 lb/acre (0.28 + 0.28 kg/ha), or mesotrione applied three times at 0.167 + 0.167 + 0.167 lb/acre (0.187 + 0.187 + 0.187 kg/ha) provided equivalent and slightly higher coverage of field paspalum than MSMA applied twice at 2.0 + 2.0 lb/acre. Applications initiated in mid to late May reduced field paspalum coverage more than earlier applications. Though mesotrione only partially reduced coverage of field paspalum with the rates and timings in our study, it has excellent turf safety on cool-season grasses and may be a suitable replacement for MSMA. However, increased efficacy is needed before mesotrione becomes commercially viable for field paspalum control.

Two separate field studies were conducted to determine the effects of mowing height, nitrogen rates, and plant growth regulator use on golf ball lie in ‘TifSport’ hybrid bermudagrass (Cynodon dactylon × C. transvalensis). The first experiment was conducted at the University of Georgia, Coastal Plain Experiment Stations, Tifton, GA. Factors at the Tifton location were nitrogen application rate (0.5, 1.0, and 1.5 lbs per 1,000 ft²per month) applied with and without trinexapac-ethyl (TE) or TE plus flurprimidol, and mowing height (0.5, 1.0, and 1.5 inches). The second project was conducted at the University of Arkansas Agricultural Research and Extension Center, Fayetteville, AR. Factors at the Fayetteville location included nitrogen application rate and mowing height (utilizing the rates and heights described above), as well as TE application frequency (monthly, every other week, and a control). Results from these two studies suggest that a 0.5-inch mowing height will improve ball lie in TifSport bermudagrass. The Georgia research determined that 1.0 lb of N per 1,000 ft²per month in combination with TE will improve ball lie, while maintaining acceptable TifSport quality. On one data collection date, the Arkansas research observed improved ball lie values when TE was applied every other week or monthly to TifSport bermudagrass maintained at a 1.5-inch mowing height.

Annual bluegrass is a problematic weed in highly maintained turfgrasses, especially when overseeding with cool-season species. Two studies were conducted on bermudagrass fairways overseeded with perennial ryegrass in South Carolina to evaluate pre- and postemergence control options for annual bluegrass when mitosis-inhibiting (MI) herbicides were no longer effective. Prodiamine at 0.84 kg ai/ha applied 60 days before overseeding (DBO) and dithiopyr at 0.56 kg ai/ha applied 45 DBO and 90 days after overseeding (DAO) provided less than 33% annual bluegrass control regardless of study or year. Greater than 90% annual bluegrass control and 80% turf density were achieved with ethofumesate at 1.1 kg ai/ha 30 and 50 DAO and ethofumesate at 1.1 kg ai/ha 30 DAO followed by bispyribac-sodium at 0.074 kg ai/ha 120 DAO. All treatments containing ethofumesate at 1.1 kg ai/ha 30 DAO provided greater than 85% annual bluegrass control regardless of year. Greater than 70% annual bluegrass control and 80% turf density was achieved with foramsulfuron at 0.028 kg ai/ha and rimsulfuron at 0.018 kg ai/ha both applied 7 DBO. Oxadiazon at 2.2 kg ai/ha 60 DBO provided 69% annual bluegrass control. This research indicates that other herbicide regimes will provide acceptable annual bluegrass control and perennial ryegrass density when MI herbicides lose their effectiveness on overseeded golf course fairways.

There are a number of ways to reduce water use in urban landscapes, but planting turfgrass cultivars that can perform and persist under restricted water is an important component of these systems. A turfgrass screening protocol has recently been developed that allows selection of cultivars that can retain green cover under acute (no water) drought stress conditions. The objective of the present study was to determine if cultivars of tall fescue (Festuca arundinacea Schreb.) and bluegrass (Poa spp.) that were selected under acute drought screening could also conserve water under restricted irrigation habits or chronic drought stress. Six cultivars of bluegrass and tall fescue were exposed to a restricted irrigation program in which plots only received water when green turfgrass coverage dropped below 40%. For the entire three-month study period, the tall fescue cultivar RK4 required 43% less supplemental irrigation than Rebel Exeda while the bluegrass cultivar, Mallard, required 55% less supplemental irrigation as Solar Green to maintain 40% green coverage. These results suggest that cultivars selected with an acute drought screening protocol can also persist with less supplemental irrigation when exposed to a chronic, restricted irrigation program.

Salinity tolerance of five Kentucky bluegrass (KBG) (Poa pratensisL.) cultivars, Mystere, BAR VV 0709, Bariris, Rugby II, and Bewitched, were tested to determine germination and seedling growth. Twenty pure live seeds of each cultivar were placed in petri dishes and hydrated with 7 mL of MgSO₄ at 0.0 (deionized water), 1.6, 3.6, or 9.0 dS/m at 25/15°C with 8/16 h photoperiod cycle for 3 weeks. In another test, seeds were planted in pots to determine seedling responses to the same saline solutions. Pots were watered daily with 70 mL of the saline solutions and seedling responses (number of seedlings and tillers and tissue dry weight) and soil salinity were determined 45 days later. All KBG cultivars showed similar germination rate (average germinated seeds = 17.2) during germination regardless of MgSO₄ levels. Soil salinity increased from 0.3 to 5.6 dS/m and 0.1 to 4.2 dS/m in Study I and II, respectively, as MgSO₄ increased from 0.0 to 9.0 dS/m. Seedling growth decreased as MgSO₄ levels increased. All five KBG cultivars responded similarly to saline solutions, except in Study II where seedling numbers were the highest in ‘Rugby II’ and ‘Bariris’ (average = 11.8) and lowest in ‘BARVV0709’ (3.0) at 1.6 dS/m. Results revealed that KBG seedling growth is more sensitive to high salinity levels than germination.

Extensive discussions of sustainability and environmental impact of golf course management have raised interest in how management can be changed to minimize impact. Management using natural organic methods is possible; however, they often do not provide the expected quality, especially during high disease pressure. In the arid West, disease pressure is much lower than humid regions, making organic management more possible. However, many factors influence turf management decisions made by golf course superintendents. We surveyed superintendents in Utah to explore management decisions and interest in organic programs, followed by online education offered on organic management. A survey in the following year explored how their practices changed in response to the education and other factors. In most cases, the superintendents themselves were the primary causes of change at their golf courses. While superintendents expressed some interest in organic practices, incentives to make those changes appeared limited. Interest in environmental issues increased, but for more than half of the respondents, no changes in management occurred. Already, Utah superintendents rely heavily on cultural practices but changes in management towards organic practices will likely require more effective products and management techniques together with interest by others at the golf course facilities.

To develop a national golf course environmental profile, a survey was sent to 16,285 superintendents at golf facilities in the United States to determine their electricity use, fuel used for heating and other purposes, fuel used for equipment and vehicles, and conservation practices at golf facilities and its agronomic regions. The response rate was 9.6%. Summed over all golf facility types and agronomic regions, estimated electricity use in 2008 was 6,714,000,000 kWh; propane use was 17,000,000 gallons; natural gas use was 17,500,000 Mcf; heating oil use was 4,400,000 gallons; gasoline use was 77,000,000 gallons; and diesel use was 50,400,000 gallons. For 18-hole golf facilities, 77% have incorporated one or more behavioral changes to their standard practices, and 71% have incorporated one or more design, physical, or mechanical changes as part of their energy conservation measures. Golf industry programs are needed to raise awareness of energy use and the opportunities for conservation at golf facilities. These results provide an accurate portrayal of golf facility energy use and establish a reference point for comparison with results from future surveys to monitor industry change over time. Data could be useful in estimating carbon use within carbon footprinting equations for the golf industry.

The response of hunting billbug, Sphenophorus venatus vestitus Chittenden (Coleoptera: Curculionidae), to insecticides was evaluated in field and laboratory bioassays. Field bioassays evaluated treatment by timing and compound. Laboratory bioassays evaluated lethal dose and lethal concentration. A field evaluation of a bifenthrin and imidacloprid combination (Allectus) suggests that it is effective at reducing adult billbug populations in North Carolina when applied in September and May/September. LD₉₅ and LC₉₅ data collected in the laboratory showed significant differences between lethal doses of neonicotinoids and pyrethroids or combination products which contain pyrethroids. Pyrethroid-containing products required lower concentrations to achieve mortality than neonicotinoids alone.