Establishment of seeded `Zenith' zoysiagrass (Zoysia japonica Steud.) in an existing sward of perennial ryegrass (Lolium perenne L.) is difficult, and chemicals arising from perennial ryegrass leaf and root tissue may contribute to establishment failure. Experiments were done to evaluate zoysiagrass emergence and growth in soil amended with perennial ryegrass leaves or roots, or after irrigation with water in which perennial ryegrass leaves or roots had previously been soaked. Compared to unamended soil, soil amended with perennial ryegrass leaves at 12% and 23% by weight reduced zoysiagrass seedling number 20% and 26%, respectively; root area and mass were reduced 50% when amendments comprised 12% of soil weight. Similar reductions in zoysiagrass seedling emergence and growth were observed in a second soil amendment study, regardless of whether perennial ryegrass was treated with glyphosate or not. Soil mixed with perennial ryegrass leaves, but not roots, at 12% by weight had a high soil conductivity (5.1 dS·m–1), which could have contributed to reduced zoysiagrass emergence and growth. More than 50% fewer zoysiagrass seedlings emerged and root mass was up to 65% lower when irrigated with water in which perennial ryegrass leaves or roots at 5, 10, or 20 g·L–1 were previously soaked for 48 hours. Zoysiagrass leaf area, and root length and area, were also lower when irrigated with water previously containing perennial ryegrass roots. Perennial ryegrass leaves and roots have the capacity to inhibit emergence and growth of `Zenith' zoysiagrass seedlings, which could negatively affect stand establishment.
Turfgrass managers in the transition zone are interested in converting swards of cool-season grasses to cold-hardy seeded bermudagrass (Cynodon dactylon) in an effort to reduce water and fungicide inputs. The objective of this study was to evaluate the potential for establishing ‘Riviera’ bermudagrass in a perennial ryegrass (Lolium perenne) sward by using a strip-seeding technique, and then to build a machine that would facilitate the process. Four, 2-inch-wide tilled rows, 1 inch deep and 15 inches apart, were created in 6 × 6-ft plots and seeded by hand with ‘Riviera’ bermudagrass at 104 lb/acre pure live seed in July 2002. In one set of strip-seeded plots, a 7-cm-wide overspray of glyphosate (≈0.5 inch on either side of the row) was applied over tilled rows after seeding to suppress perennial ryegrass further. Plots established by the strip-seeding technique exhibited 71% bermudagrass coverage after two growing seasons, and 87% coverage when rows received a glyphosate overspray. Broadcasting ‘Riviera’ seed into perennial ryegrass plots resulted in 60% bermudagrass coverage at the end of the second season of establishment. A strip seeder was constructed and used to seed ‘Riviera’ into existing perennial ryegrass turf in late July 2004 using the aforementioned row configurations and a glyphosate overspray. Coverage evaluated the following spring, before green-up, was 10.3% compared with 0% coverage where ‘Riviera’ was broadcast seeded. At the seeding rates evaluated, 79% less ‘Riviera’ bermudagrass seed was required when using the strip-seeding method, and golfers would consider the surface more amenable to play during the establishment period compared with broadcasting glyphosate and seed. A patent is pending on the strip-seeding equipment and establishment process.
Fifteen tall, warm-season, native and ornamental grasses were subjected to a 3-year, low-input, and cold hardiness trial conducted from 2010 to 2013 in zone 4a at Fargo and Mandan, ND. Grasses tested were big bluestem [species (Andropogon gerardii)], ‘Pawnee’ big bluestem (A. gerardii), silver banner grass (Miscanthus sacchariflorus), giant miscanthus (Miscanthus ×giganteus), hardy pampas grass, (Saccharum ravennae), and the following maidengrass (Miscanthus sinensis) cultivars: Silver Feather, Narrow Leaf, Blondo, Autumn Light, Condensatus, Grosse Fontaine, Morning Light, Gracillimus, Strictus, and Zebrinus. In addition to survival, the grasses were also rated for spring vigor and fall quality (0–10 scale for both evaluations), fall leaf length, and fall flower height. The grasses received no management during the trial other than irrigation during the first season and weed control. The grasses were exposed to subsurface soil temperatures (at 6-inch depth) that reached as low as −8.6 °C at the Fargo location and −6 °C at the Mandan location. The study revealed that all big bluestem (species), ‘Pawnee’ big bluestem, and silver banner grass survived at both locations; silver banner grass scored the highest spring vigor ratings; silver banner grass and ‘Pawnee’ big bluestem scored the highest fall quality ratings; silver banner grass produced the longest fall leaf length; and ‘Pawnee’ big bluestem, big bluestem (species), and silver banner grass produced the tallest fall flowers.