Rhizomes of zoysiagrass (Zoysia spp.) were subjected to controlled freezing tests in Jan. and Mar. 1993 and 1994 to determine their low-temperature tolerance. In 1994, `Belair', `Korean `Common', `Meyer', and `TGS-W10' rhizomes survived temperatures as low as -18 °C, while rhizomes of `Sunburst' survived -14 °C. `Cavalier', `Crowne', `Palisades', `Emerald', and `El Toro' were killed at -10 °C or warmer temperatures. Entries surviving exposure to -14 to -18 °C in 1994 controlled freezing tests received post-winter survival ratings in the field of 6.7 to 8.7 (9 = 100% green). Entries killed at higher freezing test temperatures were slower to recover after winter in the field, with ratings of 2.0 to 3.0. Shoot number produced after freezing was a better measurement for assessing low temperature tolerance than was shoot mass. Controlled freezing tests, using regrowth as a measure of hardiness, appear to be useful for identifying low temperature tolerance of zoysiagrasses in the early years of a field study.

Availability of newer, more competitive cool-season grasses has renewed interest in persistent, balanced warm-and cool-season species mixtures for sports turf. In this Missouri study, one-time overseedings of blends and mixtures of Kentucky bluegrass (Poa praJensis L.), perennial ryegrass (Lolium perenne L.), Chewings fescue (Festuca rubra L. subsp. commutlltll Gaud.), hard fescue (Festuca longifolia Thuill.), and creeping red fescue (Festuca rubra L. subsp. rubra Gaud.) were made on established plots of KSU S-16 and 'Midiron' bermudagrass [Cynodon dactylon (L.) Pers.). One-half of each plot was subjected to simulated traffic beginning 18 mon after overseeding, using a modified Brinkman traffic simulator. Quality of four mixtures (bermudagrass + Kentucky bluegrass, bermudagrass + perennial ryegrass, bermudagrass + perennial ryegrass + Kentucky bluegrass, and bermudagrass + perennial ryegrass + Kentucky bluegrass + Chewings fescue) remained in an acceptable range at most observation dates after 3 yr of spring-and-fall traffic. Bermudagrass control plots were in poor or marginal condition at most observation dates during the same period. Bermudagrass plus fine leaf fescues were severely damaged by simulated traffic. Quality of turf receiving no simulated traffic was generally good and varied seasonally in response to changing environmental conditions. Higher-impact absorption measurements, based on peak deceleration (maximum g) on turf receiving simulated traffic vs. no traffic, were consistent with decreasing thatch and verdure. Traction (in N·m) decreased on trafficked turf as thatch and aboveground biomass deteriorated. Kentucky bluegrass and perennial ryegrass dominated mixtures with bermudagrass after 3 yr, and showed good tolerance to simulated traffic.

Thatch accumulation is a common occurrence in lawn and sports turf and is usually detrimental. We initiated aerification, topdressing, and N treatments in July 1987, to investigate their influence on thatch, mat, quality, and color of zoysiagrass (Zoysia japonica Steud. cv. Meyer). Turfgrass color responses to N were positive and strongly linear. Turfgrass quality was generally good to excellent in response to N. However, trends were not as well defined as color responses and varied according to month and year. The aerification + topdressing combination according to N level was nonsignificant for turfgrass quality in all months and significant for color only in October. Weight of mat, which consisted mostly of rhizomes, and root weights declined linearly in response to increasing N. The root weight response is consistent with research reports of C3 turfgrasses but inconsistent with earlier studies of C4 turfgrasses where root weights increased with increasing N. Mat depth averaged over N was equal in response to topdressing vs. no topdressing. Root weights and mat weight were significantly greater with topdressing. Mat organic matter (OM) was greater with no topdressing. Our results suggest that maintenance of zoysiagrass with only enough N to provide acceptable turfgrass density and color will give the best root development in nonsandy soils. Annual topdressing with soil similar to that of the growing site may further enhance root development.

We evaluated the effect of fertilization treatments in combination with clippings disposal on perennial ryegrass (Lolium perenne L.) in two adjacent locations. Clippings left on turf during mowing decreased dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in both locations during three summers compared with clippings removed in mower baskets. However, brown patch (Rhizoctonia solani Kuhn) increased during July and Aug. 1995 when clippings were left on turf. Dollar spot was more severe with N (kg·ha–1·year–1) at 120 compared to 240; brown patch was more severe at 240. While clippings disposal had significant effects on disease incidence, implementation may not be practical because of the contrary responses of the observed diseases to this management approach.