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D.S. Gardner

Vermicomposting is the process of fragmenting organic wastes with certain species of earthworms. A variety of vermicomposts are being marketed as fertilizer materials for turfgrass management, particularly in the golf course industry. In 2002 and 2003, field trials were conducted on established kentucky bluegrass (Poa pratensis) in Columbus, Ohio, to evaluate the use of vermicomposted animal, food, paper, and turfgrass clipping waste materials as a turfgrass fertilizer under home lawn maintenance conditions. Visual quality of the plots was significantly higher for 2 weeks after application of paper vermicompost, regardless of application rate. Few other differences in either turfgrass visual quality of clipping yields were observed during a 6-week period after application, regardless of application rate or source of vermicompost. Based on the results of these studies, the use of vermicompost as a fertilizer material on established turfgrass is not warranted.

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D.S. Gardner and B.G. Wherley

Previous research on the potential of the gibberellin inhibiting growth regulator trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] to improve quality and density of shaded turfgrass has been conducted under neutral-density shade. However, some phytochrome-mediated growth responses of turfgrass, such as tillering, are different under deciduous shade versus neutral-density shade. The objectives of this study were to investigate 1) whether TE would result in improved stand density and quality of turfgrass grown under deciduous shade as has been observed under neutral-density shade and 2) the shade tolerance of sheep fescue (Festuca ovina L. `Quatro') compared to tall fescue (Festuca arundinacea Schreb. `Plantation'), and rough bluegrass (Poa trivialis L.). Trinexapac-ethyl at either 0 or 29 kg·ha–1 a.i. and nitrogen at 12 or 36 kg·ha–1 were applied on 23 May, 3 July, and 15 Aug. 2003 and 21 May 2004 to each species in a randomized complete block design under deciduous shade (about 9% of full sun). Clipping yield, color, and density data were collected for 6 weeks after the May applications in each year. Visual quality was assessed for 6 weeks after application in 2004 only. In 2003, TE significantly reduced clipping yields by 35% to 50% on sheep fescue, 58% to 76% on tall fescue and 55% to 80% on rough bluegrass. However, in 2004, yield reduction was 0% to 50% for all three species and there was no interaction between week, TE, and species. `Plantation' tall fescue had the highest overall visual quality and density. Sheep fescue also provided an acceptable quality turf stand. TE application did not significantly impact the quality of these species. Rough bluegrass performance was unacceptable, and high rate applications of TE to this species in shade resulted in significant (P < 0.05) losses in density. Trinexapac-ethyl application, based on the results of this study, may not enhance turf quality of cool season grasses grown under dense tree shade.

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Stephanie C. Hamel and Joseph R. Heckman

Recent changes in soil testing methodology, the important role of P fertilization in early establishment and soil coverage, and new restrictions on P applications to turf suggest a need for soil test calibration research on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb), and perennial ryegrass (Lolium perenne L.). Greenhouse and field studies were conducted for 42 days to examine the relationship between soil test P levels and P needs for rapid grass establishment using 23 NJ soils with a Mehlich-3 extractable P ranging from 6 to 1238 mg·kg–1. Soil tests (Mehlich-1, Mehlich-3, and Bray-1) for extractable P were performed by inductively coupled plasma–atomic emission spectroscopy (ICP). Mehlich-3 extractable P and Al were measured to evaluate the ratio of P to Al as a predictor of need for P fertilizer. Kentucky bluegrass establishment was more sensitive to low soil P availability than tall fescue or perennial ryegrass. Soil test extractants Mehlich-1, Bray-1, or Mehlich-3 were each effective predictors of need for P fertilization. The ratio of P to Al (Mehlich-3 P/Al %) was a better predictor of tall fescue and perennial ryegrass establishment response to P fertilization than soil test P alone. The Mehlich-1, Bray-1, and Mehlich-3 soil test P critical levels for clipping yield response were in the range of 170 to 280 mg·kg–1, depending on the soil test extractant, for tall fescue and perennial ryegrass. The Mehlich-3 P/Al (%) critical level was 42% for tall fescue and 33% for perennial ryegrass. Soil test critical levels, based on estimates from clipping yield data, could not be determined for Kentucky bluegrass using the soils in this study. Soil testing for P has the potential to aid in protection of water quality by helping to identify sites where P fertilization can accelerate grass establishment and thereby prevent soil erosion, and by identifying sites that do not need P fertilization, thereby preventing further P enrichment of soil and runoff. Because different grass species have varying critical P levels for establishment, both soil test P and the species should be incorporated into the decision-making process regarding P fertilization.

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Patrick E. McCullough, Haibo Liu, and Lambert B. McCarty

Plant growth regulators are applied to inhibit uneven shoot growth of putting green turf but research is limited on responses of dwarf-type bermudagrass cultivars to growth inhibition. Experiments were conducted at the Clemson University Greenhouse Complex with `Champion' and `TifEagle' bermudagrass grown in polyvinylchloride containers with 40 cm depths and 177 cm2 areas built to United States Golf Association specification. Flurprimidol was applied at 0.14, 0.28, and 0.48 kg·ha–1 a.i. and paclobutrazol at 0.14 kg·ha–1 a.i. on separate containers. Flurprimidol at 0.28 and 0.42 kg·ha-1 caused 17% and 31% reduction in turf color 5 weeks after treatment (WAT), respectively. `Champion' exhibited unacceptable turf injury (>30%) 2 WAT from paclobutrazol and all flurprimidol rates. `TifEagle' had unacceptable turf injury from flurprimidol at 0.42 kg·ha–1 2 WAT, 0.28 kg·ha–1 3 WAT, and 0.14 kg·ha–1 4 WAT that did not recover. Moderate injury (16% to 30%) was observed from paclobutrazol on `TifEagle' but ratings were acceptable. After 6 weeks, flurprimidol at 0.14, 0.28, and 0.42 kg·ha–1 reduced bermudagrass green shoot density (GSD) per square centimeter by 20%, 40%, and 40%, respectively, while paclobutrazol reduced GSD 12%. `TifEagle' total clipping yield was reduced 60%, 76%, and 86% from flurprimidol at 0.14, 0.28, and 0.42 kg·ha–1, respectively, and 37% from paclobutrazol. `Champion' total clipping yield was reduced 82%, 90%, and 90% from flurprimidol at 0.14, 0.28, and 0.42 kg·ha–1, respectively, and 58% from paclobutrazol. After 6 weeks, flurprimidol reduced `Champion' total root mass by 44% over all three rates. `Champion' treated with paclobutrazol had similar total root mass to the untreated. `TifEagle' treated with all PGRs had similar rooting to the untreated. Overall, flurprimidol will likely not be suitable for dwarf bermudagrass maintenance at these rates; however paclobutrazol may have potential at ≤0.14 kg·ha–1. Chemical names used: Flurprimidol {α-(1-methylethyl)-α-[4-(trifluoro-methoxy) phenyl] 5-pyrimidine-methanol}; Paclobutrazol, (+/-)–(R*,R*)-β-[(4-chlorophenyl) methyl]-α-(1, 1-dimethyl)-1H-1,2,4,-triazole-1-ethanol.

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Cerinda Loschinkohl and Michael J. Boehm

The effects of incorporation of compost to a disturbed urban soil on turfgrass establishment, growth, and rust severity were assessed in a replicated field study. A blend of two locally available composted biosolids (sewage sludge) was incorporated into a nutrient-deficient subsoil at a rate of 130 m3·ha-1, adding NO3-N, P, and K at 126, 546, and 182 kg·ha-1, respectively, to each compost-amended plot. Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and a mixture of these two species were seeded into both compost-amended and nonamended plots and observed for 1 year. Turfgrass establishment estimated from visual assessments of percentage cover and growth measured by clipping yields were significantly (P < 0.05) enhanced by the incorporation of the composted biosolids. These effects were first observed and most pronounced on plots seeded with perennial ryegrass and were apparent for the duration of the study. The severity of leaf rust caused by Puccinia sp. was significantly (P < 0.05) less on perennial ryegrass seeded on the compost-amended plots. This study demonstrates the feasibility and potential benefits of amending disturbed urban soils with composted biosolids to enhance turfgrass establishment and is the first report of the suppression of a foliar turfgrass disease through the incorporation of compost into soil.

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Patrick E. McCullough, Haibo Liu, Lambert B. McCarty, and Ted Whitwell

Research was conducted in two studies at the Clemson University Greenhouse Complex, Clemson, S.C., with the objective of evaluating `TifEagle' bermudagrass (Cynodon dactylon × C. transvaalensis) response to paclobutrazol. TifEagle bermudagrass plugs were placed in 40 cm polyvinylchloride containers, with 20.3-cm-diameters and built to U.S. Golf Association specifications with 85 sand: 15 peatmoss (by volume) rootzone mix. Paclobutrazol was applied to separate containers at 0, 0.14, 0.28, and 0.42 kg·ha-1 (a.i.) per 6 weeks. Minor phytotoxicity occurred with 0.14 kg·ha-1 applications, but turf quality was unaffected. Severe bermudagrass phytotoxicity occurred from paclobutrazol at 0.28 and 0.42 kg·ha-1. Total clipping yield from 12 sampling dates was reduced 65%, 84%, and 92% from 0.14, 0.28, and 0.42 kg·ha-1, respectively. Root mass after 12 weeks was reduced 28%, 45%, and 61% for turf treated 0.14, 0.28, and 0.42 kg·ha-1, respectively. Paclobutrazol reduced root length 13%, 19%, and 19% by 0.14, 0.28, and 0.42 kg·ha-1, respectively. Turf discoloration and negative rooting responses advocate caution when using paclobutrazol on `TifEagle' bermudagrass. Chemical names used: (+/-)-(R*,R*)-ß-[(4-chlorophenyl) methyl]-alpha-(1, 1-dimethyl)-1H-1,2,4,-triazole-1-ethanol (paclobutrazol).

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Tracy Dougher, Toby Day, Paul Johnson, Kelly Kopp, and Mark Majerus

The ongoing drought in the Intermountain West has brought a great deal of attention to water conservation over the past several years. During that time, turfgrass irrigation has been targeted as a source for large potential water savings. Some communities promote downsizing turfgrass areas as the best water conservation measure. In reality, turfgrass controls erosion, reduces evaporation from a site, and provides a safe surface for human activities. One alternative to elimination would be wider use of low water-use-grasses appropriate to the area. However, many questions arise regarding the choice of such grasses and their management. Our research addresses these questions. Plots have been established at Montana State University, Bozeman; Utah State University, Logan; and USDA-NRCS Plant Materials Center, Bridger, Mo. The grasses considered include 12 single species and 12 mixed species stands of `Cody' buffalograss, `Foothills' Canada bluegrass, `Bad River' blue grama, sheep fescue, sandberg bluegrass, muttongrass, and wheatgrasses `Sodar' streambank, `Road Crest' crested, `Rosana' western, and `Critana' thickspike with Kentucky bluegrass and tall fescue as controls. Line source irrigation allowed the plots to be evaluated at a number of levels of irrigation. Experimental measurements on the plots included growth response as determined by clipping yield and quality ratings, and species composition. Fescues and wheatgrasses retained their color, texture, and density throughout the growing season, regardless of moisture level. Warm-season grasses performed well in June, July, and August only, and worked poorly in mixtures as the green cool-season grasses could not mask the brown dormant leaves in cooler weather.

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Haibo Liu and Richard J. Hull

Economic and environmental concerns over nitrogen (N) fertilization of turfgrasses are prompting serious considerations of how to best use various N pools in turf-soil ecosystems. Nitrogen in clippings is receiving special consideration but information on how large and variable this N source might be for different turfgrasses is limited. Therefore, a field study investigated growth of and N recovery in clippings from 10 cultivars each of kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.) turf at the University of Rhode Island Turfgrass Research Station, Kingston, during 1990 and 1991 growing seasons. All turf had been established in 1985, 1986 or 1987 on an Enfield silt loam (Coarse loamy over sandy skeletal, mixed, mesic, Typic Dystrochrepts) and maintained under N fertilization rate of 147 kg N ha/year. Daily clipping growth rate (DCG), leaf blade N concentration (NC), and daily N recovery rate (DNR) in clippings were compared across species and cultivars. Seasonal clipping yields ranged from 5152 kg dry weight/ha for tall fescue to 3680 kg·ha–1 for perennial ryegrass. Significant species differences in the amount and seasonal pattern of N recovery were identified. Cultivar differences in N recovery were greatest for kentucky bluegrass but much less for perennial ryegrass and tall fescue. Total N recovery in clippings ranged from 260 to 111 kg N/ha/year generally exceeded N supplied as fertilizer, thus emphasizing potential importance of clipping N in turf management.

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Patrick E. McCullough, Haibo Liu, and Lambert B. McCarty

Trinexapac-ethyl (TE) is an effective plant growth retardant for hybrid bermudagrass; however, growth responses of various dwarf-type bermudagrass cultivars to TE have not been reported. Two 60-day greenhouse experiments were conducted at the Clemson Greenhouse Research Complex, Clemson, S.C., to evaluate the response of `Champion', `FloraDwarf', `MiniVerde', `MS Supreme', `Tifdwarf', and `TifEagle' bermudagrass with and without TE at 0.0125 kg·ha-1 a.i. per 10 days. From 20 to 60 days after initial treatments, TE enhanced visual quality 9% to 13% for all cultivars. From four samples, TE reduced clippings 63%, 63%, 69%, 62%, 64%, and 46% for `Champion', `FloraDwarf', `MiniVerde', `Tifdwarf', and `TifEagle', respectively. Trinexapac-ethyl enhanced root mass 23% and 27% for `MiniVerde' and `FloraDwarf' bermudagrass, respectively. `Champion', `MS Supreme', `Tifdwarf', and `TifEagle' bermudagrass treated with TE had similar root mass to the untreated respective cultivars. Among untreated cultivars, `FloraDwarf', `MiniVerde', `MS Supreme', and `Tifdwarf' had similar root masses; however compared to these cultivars, `Champion' and `TifEagle' had 33% and 81% less root mass, respectively. Root length was unaffected by TE; however, `Champion' and `TifEagle' averaged 20% and 36% less root length compared to `Tifdwarf' bermudagrass, respectively, while `FloraDwarf', `MiniVerde', and `MS Supreme' had similar root length to `Tifdwarf'. Trinexapac-ethyl safely enhanced turf quality and reduced clipping yield at 0.0125 kg·ha-1 per 10 days without inhibiting root growth of six dwarf-type bermudagrasses. Chemical name used: [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] (trinexapac-ethyl).

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Patrick E. McCullough, Haibo Liu, and Lambert B. McCarty

Ethephon is an effective growth retardant for suppressing Poa annua (L.) seedheads in creeping bentgrass putting greens; however, ethylene induction may cause bentgrass leaf chlorosis, reduced rooting, and quality decline. Two greenhouse experiments investigated the effects of nitrogen (N) fertility and ethephon applications on `L-93' creeping bentgrass over 9 weeks. Ethephon was applied at 0, 3.8, and 7.6 kg·ha–1 a.i. per 3 weeks and N was applied at 4 and 8 kg·ha–1·week–1. Ethephon applications linearly reduced bentgrass quality on every weekly observation. Increased N rate to 8 kg·ha–1·week–1 improved turf quality about 10% to 20% and 10% to 30% from ethephon applied at 3.8 and 7.6 kg·ha–1 per 3 weeks, respectively. Increased N rate to 8 kg·ha–1·week–1 enhanced shoot growth 30% but reduced root mass and length 12% and 11%, respectively. After 9 weeks, ethephon reduced root length by about 30% and root mass about 35% at both rates. From nine weekly samples, ethephon reduced dry clipping yield 10% and 16% at 3.8 and 7.6 kg·ha–1 per 3 weeks, respectively. From 2 to 9 weeks after initial treatments, ethephon linearly increased leaf water content. Increasing N fertility effectively reduced bentgrass leaf chlorosis from ethephon; however, repeat applications of ethephon and increased N may restrict bentgrass root growth. Chemical names used: [(2-chloroethyl)phosphonic acid] (ethephon).