International Turfgrass Society Research Journal最新文献

Annual bluegrass (Poa annua L.) is a problematic weed in turfgrass that has evolved resistance to 12 different herbicide sites of action. The mitotic inhibiting herbicide pronamide has both pre- and postemergence activity on susceptible annual bluegrass populations, but on certain resistant populations, postemergence activity is hypothetically compromised due to lack of root uptake or due to an unknown foliar resistance mechanism. Spray droplet size may affect foliar and soil deposition of pronamide, thus potentially explaining variation in population control or differential shoot and root uptake. Greenhouse experiments were conducted to quantify pronamide, flazasulfuron, and pronamide + flazasulfuron (a common tank mixture) deposition on annual bluegrass as affected by spray-droplet size. Five droplet sizes (200, 400, 600, 800, and 1,000 μm) were sprayed in an enclosed spray chamber on two- to three-leaf stage annual bluegrass plants. Fluorescent dye was added to each treatment solution to quantify the effects of herbicide and spray droplet size on herbicide deposition. Results indicate that spray droplet size affects deposition of pronamide and flazasulfuron, applied alone and in combination, on annual bluegrass. The highest foliar deposition was produced with 400-μm spray droplets in pronamide treatments and with 200 μm spray droplets in flazasulfuron and pronamide + flazasulfuron treatments. The addition of flazasulfuron to pronamide did not affect herbicide deposition when compared with pronamide-alone treatments. Results suggest that 200- to 400-μm spray droplets are optimal for foliar deposition of pronamide. Alternatively, larger droplet sizes may facilitate better soil deposition of pronamide where root uptake is optimal.

New Zealand produces no commercial seed of any native grass species. All grasses used in agriculture and turf have evolved on other continents, and most natives fail to compete in mown turf or grazed pasture. Is this simply because of a lack of research or the lack of native grazing animals, or is there something fundamentally different about the New Zealand flora? New Zealand has many indigenous species within genera containing known turf species such as Festuca, Poa, Agrostis, Deschampsia, and Zoysia, but most are rare in the modern landscape. After collecting and screening over 50 native species for potential use in turf or pasture, it was apparent that most lacked vigor; were unable to form a turf; had slow establishment, extended flowering periods, poor seed yields, seeds with long awns, or seed that shattered readily; or had other difficulties with harvesting. One of the native grasses that showed promise was Poa imbecilla Spreng., which formed a very fine turf and had seed production characteristics suitable for development as a commercial species. It established readily but was usually dominated by introduced species within a few years. A cultivar was developed from local material, ‘Stewarts’, which is suitable for fine turf and for native grass revegetation and is now in limited commercial production.

For over forty years, the National Turfgrass Evaluation Program (NTEP) has coordinated trials and collected data on turfgrass traits from multiple species and sites across the U.S. and Canada. These trials are used worldwide for turfgrass cultivar improvement, sales and selection by everyone from researchers to turfgrass professionals to hobbyist turfgrass managers. However, using the NTEP web site (www.ntep.org), consisting of static, PDF or HTML-based tables to select grasses does not allow for customized results based on geography, specific site conditions or management levels. Therefore, the identification of sustainable turfgrasses within NTEP data is currently difficult and in need of improvement.

Vegetation management around roadsides and guardrails is time-consuming and expensive for a department of transportation. These organizations desire dense vegetation that has slow vertical growth and minimal weed invasion once established, and zoysiagrass (Zoysia spp.) is a suitable species for this use. The objective of this study was to compare fall versus spring plantings for establishing zoysiagrass on North Carolina roadsides. ‘Crowne’ (sprigs) and ‘Compadre’ (sprigs and seed) zoysiagrasses (Zoysia japonica Steud.) were planted in fall 2017 (September, October, November) and spring 2018 (March, April, May) in Lenoir and Yadkin Counties, NC. Data collection was initiated in summer of 2018 and continued through July 2019. The mean percentage of zoysiagrass cover was recorded individually for each establishment timing and method. Zoysiagrass planted with seed achieved coverage quicker than sprigging for all monthly plantings. In Yadkin, March and May seedings achieved 95 and 98% coverage in September 2018, respectively; whereas Compadre's sprigging coverage was 67%. In Lenoir, seed planted in November 2017 and March 2018 achieved 32 and 35% cover by September 2018, respectively, whereas sprig plantings showed <6% coverage. Coverage was faster for spring-planted materials, but after one calendar year, fall and spring seed planting had similar coverage. The results from this research suggest that zoysiagrass can be established with minimal inputs in fall as well as spring on North Carolina roadsides.

The aim of this study was to establish the mechanisms underpinning the observations made in a field trial that suggested that a novel surfactant treatment could promote bentgrasses (Agrostis spp.) in golf greens that contain annual meadow grass (Poa annua L.). Assessments of the effects of three surfactant treatments (named Treatments 1, 2, and 3) on shoot height, biomass accumulation, rhizosheath properties, soil water distribution, and rooting characteristics were made over the course of two experiments carried out under controlled conditions. We found that the leaf extension rate was significantly affected in the two grass species to different extents, depending on the surfactant used. This finding could have positive implications for turf quality in the field for a newly developed formulation (Treatment 3), which was observed to be the case in the field trial that pre-dated this study. The same treatment also resulted in significant differences in the grasses in terms of rhizosheath size compared with untreated soil. We found that surfactants affected the distribution of water in the soil by increasing the rhizosheath water content to bulk soil water content ratio, potentially maximizing water and nutrient uptake by the roots. The combination of effects observed with use of the novel surfactant treatment may lead to improved water use efficiency and a more desirable sward composition for golf greens.