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Qi Zhang and Kevin Rue

Saline and alkaline conditions often coexist in nature. Unlike salinity that causes osmotic and ionic stresses, alkalinity reflects the impact of high pH on plant growth and development. In this research, seven turfgrass species, tall fescue (Festuca arundinacea Schreb.), kentucky bluegrass (Poa pratensis L.), creeping bentgrass (Agrostis stolonifera L.), perennial ryegrass (Lolium perenne L.), zoysiagrass (Zoysia japonica Steud.), bermudagrass [Cynodon dactylon var. dactylon (L.) Pers.], and alkaligrass [Puccinellia distans (Jacq.) Parl.], were germinated under 10 saline–alkaline conditions [two salinity concentrations (25 and 50 mm) × five alkalinity levels (pH = 7.2, 8.4, 9.1, 10.0, 10.8)] in a controlled environment. Seed germination was evaluated based on final germination percentage and daily germination rate. Alkaligrass and kentucky bluegrass showed the highest and lowest germination under saline conditions, respectively. Limited variations in germination were observed in other species, except bermudagrass, which showed a low germination rate at 50 mm salinity. Alkalinity did not cause a significant effect on seed germination of tested turfgrass species.

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Grady L. Miller and Adam Thomas

Application of nutrients to correct nutrient deficiencies in turfgrasses are often based on tissue analysis. Previous research has indicated that near infrared reflectance spectroscopy (NIRS) may be useful in tissue nutrient concentration determination since it requires minimum sample preparation and has been a reliable predictor of N concentration. The objective of this study was to evaluate the reliability of NIRS in determining P, K, Ca, and Mg concentrations in bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy]. Tissue samples were collected from Florida golf courses, representing different cultivars grown under various conditions and fertilizer regimes. Tissue samples were analyzed using NIRS and traditional wet chemistry (Mehlich-1 extracts analyzed using inductively coupled argon spectrophotometer) before results were statistically compared. Results from wet chemistry analysis averaged 15% lower than those obtained from NIRS. Although results for certain cultivars and elements were positively correlated (`Tifdwarf' Ca, r 2 = 0.72; P < 0.01), precision across all cultivars and nutrients was not sufficient (accounted for only 26% of variability) to indicate that NIRS would be an effective management tool for the elements evaluated in this study.

Open access

Alex J. Lindsey, Joseph DeFrank, and Zhiqiang Cheng

The use of nonpotable water for irrigation on various sport venues has led to an increased use of seashore paspalum (Paspalum vaginatum) turf in Hawaii. An ongoing challenge many seashore paspalum turf managers struggle with is bermudagrass (Cynodon dactylon) infestations. Herbicide efficacy studies were conducted at the Hoakalei Country Club [‘SeaDwarf’ seashore paspalum (fairway cut)] and the Magoon Research Station [‘SeaStar’ seashore paspalum (grown in container)] on the island of Oahu in Hawaii. Spray applications of the herbicides mesotrione, topramezone, metribuzin, and ethofumesate were evaluated alone and in tank mixtures for bermudagrass suppression and seashore paspalum injury. At the Hoakalei Country Club, maximum bermudagrass injury with minimal seashore paspalum discoloration was obtained with tank mixes of mesotrione (0.06 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.02 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre). Unacceptable seashore paspalum turf injury was obtained in all treatments that did not include metribuzin. At the Magoon Research Station, maximum selective bermudagrass suppression was achieved with tank mixes of topramezone (0.01 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.01 lb/acre) + metribuzin (0.09 lb/acre) + ethofumesate (1.00 lb/acre). The addition of metribuzin and/or ethofumesate to the tank mix safened (reduced turf discoloration) seashore paspalum to topramezone or mesotrione foliar bleaching. Tank mixes of mesotrione, topramezone, metribuzin, and ethofumesate have the potential for bermudagrass suppression and control of other grassy weeds in seashore paspalum turf.

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E.A. Guertal and J.N. Shaw

A 3-year study was conducted in Auburn, Ala., on an established hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy `Tifway'] stand maintained at a 2.54-cm mowing height. Treatments were level of soil traffic applied via a weighted golf cart to produce turf and soil that received varying amounts of traffic. Dormant bermudagrass was overseeded with perennial ryegrass (Lolium perenne L.) each October, which remained until May of each year. Spectral data were collected monthly using a multispectral radiometer. Percent reflectance data were acquired over 512 discrete wavelengths in visible (VIS) and near-infrared (NIR) ranges. Quarterly data collection included soil penetrometer and bulk density measurements to a depth of 15 cm. After 2 years of traffic, both soil penetrometer and bulk density data indicated statistically significant increases in soil compaction. In general, as traffic increased there were also increases in percent reflectance in the VIS range. Data were subject to temporal variation, however, as values changed with the date of sample collection. The NIR reflectance data provided little consistent correlation to measurements of soil compaction. Use of NIR and VIS radiometry to evaluate turf stress showed some potential, but temporal variation must be considered.

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Lambert B. McCarty, Raymond K. McCauley, Haibo Liu, F. Wesley Totten, and Joe E. Toler

Overseeded perennial ryegrass (Lolium perenne L.) aggressively competes with bermudagrass [Cynodon dactylon (L.) Pers.] for resources and may adversely affect spring transition by releasing allelochemicals into the environment. Growth chamber studies examined germination and growth of ‘Arizona Common’ bermudagrass in soil amended with 0%, 2%, 12%, or 23% perennial ryegrass root or shoot debris or in soil treated with irrigation water in which perennial ryegrass roots at 0, 5, 10, or 20 g·L−1 or shoots at 0, 10, or 20 g·L−1 had been soaked. Inhibitory effects on bermudagrass germination and growth were most extensive when soil was amended with ryegrass shoot debris, because germination, root ash weight, root length density, and root mass density were reduced 33%, 55%, 30%, and 52%, respectively. Soil amended with ryegrass root debris only inhibited bermudagrass-specific root length. Application of irrigation water containing either ryegrass root or shoot extracts only inhibited bermudagrass-specific root length. In conclusion, results obtained when soil was amended with shoot debris demonstrated perennial ryegrass can inhibit bermudagrass germination and growth in controlled environments.

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Jennifer M. Johnson-Cicalese and C.R. Funk

Studies were conducted on the host plants of four billbug species (Coleoptera:Curculionidae: Sphenophorus parvulus Gyllenhal, S. venatus Chitt., S. inaequalis Say, and S. minimus Hart) found on New Jersey turfgrasses. A collection of 4803 adults from pure stands of various turfgrasses revealed all four billbugs on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb.), and perennial ryegrass (Lolium perenne L.), and S. parvulus, S. venatus, and S. minimus on Chewings fescue (F. rubra L. ssp. commutata Gaud.). Since the presence of larvae, pupae, or teneral adults more accurately indicates the host status of a grass species, immature billbugs were collected from plugs of the various grass species and reared to adults for identification. All four species were reared from immature billbugs found in Kentucky bluegrass turf; immatures of S. venatus, S. inaequalis, and S. minimus were found in tall fescue; S. venatus and S. minimus in perennial ryegrass; and S. inaequalis in strong creeping red fescue (F. rubra L. ssp. rubra). A laboratory experiment was also conducted in which billbug adults were confined in petri dishes with either Kentucky bluegrass, perennial ryegrass, tall fescue, or bermudagrass (Cynodon dactylon Pers.). Only minor differences were found between the four grasses in billbug survival, number of eggs laid, and amount of feeding. In general, bermudagrass was the least favored host and the other grasses were equally adequate hosts. The results of this study indicate a need for updating host-plant lists of these four billbug species.

Full access

Chanjin Chung, Tracy A. Boyer, Marco Palma, and Monika Ghimire

This study estimates potential economic impacts of developing drought- and shade-tolerant bermudagrass (Cynodon dactylon) turf varieties in five southern states: Texas, Florida, Georgia, Oklahoma, and North Carolina. First, estimates are provided for the market-level crop values of the newly developed two varieties for each state. Then, an economic impact analysis is conducted using an input–output model to assess additional output values (direct, indirect, and induced impacts), value added, and employment due to the new varieties. Our results indicate that the two new varieties would offer significant economic impacts for the central and eastern regions of the United States. Under the assumption of full adoption, the two new products would generate $142.4 million of total output, $91.3 million of value added, and 1258 new jobs. When a lower adoption rate is assumed at 20%, the expected economic impacts would generate $28.5 million of output, $18.3 million of value added, and 252 jobs in the region. Our findings quantify the potential economic benefits of development and adoption of new turfgrass varieties with desirable attributes for residential use. The findings suggest that researchers, producers, and policymakers continue their efforts to meet consumers’ needs, and in doing so, they will also reduce municipal water consumption in regions suited to bermudagrass varieties.

Free access

G.E. Bell, B.M. Howell, G.V. Johnson, W.R. Raun, J.B. Solie, and M.L. Stone

Differences in soil microenvironment affect the availability of N in small areas of large turfgrass stands. Optical sensing may provide a method for assessing plant N needs among these small areas and could help improve turfgrass uniformity. The purpose of this study was to determine if optical sensing was useful for measuring turfgrass responses stimulated by N fertilization. Areas of `U3' bermudagrass [Cynodon dactylon (L.) Pers.], `Midfield' bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], and `SR1020' creeping bentgrass (Agrostis palustris Huds.) were divided into randomized complete blocks and fertilized with different N rates. A spectrometer was used to measure energy reflected from the turfgrass within the experimental units at 350 to1100 nm wavelengths. This spectral information was used to calculate normalized difference vegetation index (NDVI) and green normalized difference vegetation index (GNDVI). These spectral indices were regressed with tissue N and chlorophyll content determined from turfgrass clippings collected immediately following optical sensing. The coefficients of determination for NDVI and GNDVI regressed with tissue N averaged r 2 = 0.76 and r2 = 0.81, respectively. The coefficients of determination for NDVI and GNDVI regressed with chlorophyll averaged r 2 = 0.70 and r 2 = 0.75, respectively. Optical sensing was equally effective for estimating turfgrass responses to N fertilization as more commonly used evaluations such as shoot growth rate (SGR regressed with tissue N; r 2 = 0.81) and visual color evaluation (color regressed with chlorophyll; r 2 = 0.64).

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Mark J. Gatschet, Charles M. Taliaferro, Jeffrey A. Anderson, David R. Porter, and Michael P. Anderson

Cold acclimation (CA) of `Midiron' and `Tifgreen' turf bermudagrasses (Cynodon dactylon L. Pers. × C. transvaalensis Burtt-Davy) induced tolerance to lower freezing temperatures and altered protein synthesis in crowns. LT50 (lethal temperature for 50% of plants) values were lowered ≈5C after 4 weeks in controlled-environment chambers under CA [8/2C (day/night) cycles with a 10-hour photoperiod] vs. non-CA (28/24C) conditions. LT50 values for `Midiron' plants decreased from -6.5 to -11.3C after CA and from -3.6 to -8.5C for `Tifgreen'. Proteins synthesized by isolated crowns were radiolabeled in vivo for 16 hours with 35 S-methionine and 35 S-cysteine. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and fluorography revealed increased synthesis of several cold-regulated (COR) proteins in CA crowns of both cultivars. Synthesis of intermediate molecular weight (MW) (32 to 37 kDa) and low-MW (20 to 26 kDa) COR proteins was greater in `Midiron' than `Tifgreen' crowns.

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Kenneth B. Marcum, Mohammad Pessarakli, and David M. Kopec

Relative salinity tolerance of 21 desert saltgrass accessions (Distichlis spicata [L.] Greene var. stricta (Torr.) Beetle), and one hybrid bermudagrass `Midiron' (Cynodon dactylon [L.] Pers. var. dactylon × C. transvaalensis Burtt-Davy `Midiron') were determined via solution culture in a controlled-environment greenhouse. Salinity in treatment tanks was gradually raised, and grasses progressively exposed to 0.2, 0.4, 0.6, 0.8, and 1.0 m total salinity in sequence. Grasses were held at each salinity level for 1 week, followed by determination of relative salinity injury. Relative (to control) live green shoot weight (SW), relative root weight (RW), and % canopy green leaf area (GLA) were highly correlated with one-another (all r values >0.7), being mutually effective indicators of relative salinity tolerance. The range of salinity tolerance among desert saltgrass accessions was substantial, though all were more tolerant than bermudagrass. Accessions A77, A48, and A55 suffered little visual shoot injury, and continued shoot and root growth at a low level, when exposed up to 1.0 m (71,625 mg·L–1); sea water is about 35,000 mg·L–1), and therefore can be considered halophytes.