differences in bermudagrass cultivars' response in tolerance to simulated athletic traffic. These studies also reported that in native soil conditions, the finer-textured, denser cultivars performed better under simulated athletic traffic. The transition zone
Michael T. Deaton and David W. Williams
Marco Volterrani, Nicola Grossi, Monica Gaetani, Lisa Caturegli, Aimila-Eleni Nikolopoulou, Filippo Lulli, and Simone Magni
growth or seed head formation while preserving stolon growth ( McCarty, 2011 ). Volterrani et al. (2012) reported a significant reduction of stolon length when TE was applied on ‘Patriot’ hybrid bermudagrass over the labeled rate. The available data on
J.B. Beard, R.L. Green, and S.I. Sifers
Cultivar selection is one method used for the conservation of irrigation water. The primary objective of this research was to evaluate the evapotranspiration (ET) rates of 24 well-watered, turf-type bermudagrass (Cynodon spp.) genotypes under field conditions and established on a fritted clay root zone contained in plastic minilysimeter pots. A secondary objective was to correlate ET rate to leaf extension rate, a potential rapidly assessed predictor of the amount of leaf surface area present for ET. ET rates were determined by the water-balance method. Both the overall ET and leaf extension rate differed significantly among genotypes. ET rates were not correlated with leaf extension rates in individual years. Our data indicated a potential for water savings based on bermudagrass cultivar selection that was similar to the reported potential water savings based on warm-season turfgrass species selection.
Eight demethylation inhibiting (DMI) fungicides were applied at two rates to `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. ×x C. transvaalensis Burtt-Davy] to determine if DMI fungicides would produce a plant growth regulation effect on healthy bermudagrass. After three applications at 28- to 30-day intervals, compared to the control, both rates of cyproconazole, bromuconazole, propiconazole and triadimefon and the high rate of myclobutanil significantly decreased turfgrass quality on at least one evaluation date in each year of the study. The low rate of myclobutanil and both rates of tebuconazole and fenbuconazole did not adversely effect turfgrass quality in either year. For both rates of fenarimol, there was only one date during both years of the study when the turfgrass quality was significantly lower than the control. These results demonstrate the wide range of physiological activity the DMI fungicides can have on bermudagrass.
R.N. Carrow and B.J. Johnson
A turfgrass wear injury study was conducted at Griffin, Ga., on `Tifway' bermudagrass (Cynodon dactylon × C. transvaalensis) using two golf car tires and three golf car types driven in a semicircular pattern to deliver 85 passes over the tread path plot area. Wear injury for the 14 days after wear was applied was assessed by visual quality, percent green coverage, leaf bruising, and verdure. Golf tire × car interactions occurred, but more wear occurred with the low pressure (48 × 103 Pa), dimpled tread tire with flexible sidewalls than the commonly used bias ply (4-ply), V-shaped tread tire with more rigid sidewalls. Significant differences in wear damage occurred for golf car type but were influenced by tire design. Thus, selection of golf car tire and golf car type can influence the degree of wear injury on turfgrass sites.
George H. Snyder and John L. Cisar
Field and laboratory studies were conducted to evaluate the K retention properties of several resin-coated (RC), sulfur-coated (SC), and plastic-coated (PC) K fertilizers. Substantial differences in K release were found among the controlled-release K materials, based both on the K content of `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davvy] clippings and on direct measurement of K remaining in fertilizer granules in the field over time. One SC material appeared to release K too rapidly, and one RC material appeared to release K too slowly to be useful for providing extended plant-available K to turfgrass. The other sources appeared to have release characteristics that would be favorable for turfgrass maintenance. Because differences in K release were observed among the sources, a laboratory method for assessing K release would be useful. Toward this-end, models were developed relating K retention of sources in hot water (70C) to K retention under field conditions.
Patrick E. McCullough, Haibo Liu, Lambert B. McCarty, and Joe E. Toler
Dwarf-type bermudagrass (Cynodon dactylon Pers. × C. transvaalensis Burtt-Davy) putting greens tolerate long-term mowing heights of 3.2 mm but require heavy nitrogen (N) fertilizations that increase ball roll resistance. Applying a plant growth regulator, such as trinexapac-ethyl (TE), could reduce uneven shoot growth from high N fertility and improve putting green ball roll distances. Field experiments were conducted from April to August 2003 and 2004 in Clemson, SC to investigate effects of ammonium nitrate applied at 6, 12, 18, or 24 kg N/ha per week with TE applied at 0 or 0.05 kg a.i. per ha every 3 weeks on `TifEagle' bermudagrass ball roll distances (BRD). BRD were measured weekly with a 38-cm stimpmeter in the morning (900 to 1100 hr) and evening (>1700 hr) beginning 1 wk after initial TE treatments. Interactions were not detected among N, TE, or time of day. TE increased BRD about 15% from non-TE treated. BRD was reduced with increased N rate and from am to pm; however, bermudagrass treated with TE averaged 10% longer PM BRD than am distances of non-TE treated. Overall, increased N fertility and diurnal shoot growth may reduce BRD but TE will be an effective tool for mitigating these effects on bermudagrass putting greens. Chemical name used: [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] (trinexapac-ethyl).
Alan L. Wright, Tony L. Provin, Frank M. Hons, David A. Zuberer, and Richard H. White
Application of organic amendments can increase dissolved organic C (DOC) concentrations, which may influence movement of nutrients and heavy metals in soils. The objectives of this study were to investigate the influence of compost sources and application rates on concentrations of soil DOC, NO3-N, and extractable P over 29 months after a one-time application of compost to bermudagrass [Cynodon dactylon (L.) Pers.] turf. Few differences were evident between compost sources for soil total organic C (TOC), DOC, and NO3-N. However, the initial P content of compost sources significantly influenced soil extractable P. Increasing the rate of compost application increased soil TOC initially, but levels remained fairly stable over time. In contrast, DOC continued to increase from 3 to 29 months after application, suggesting that compost mineralization and growth of bermudagrass contributed to DOC dynamics in soil. Dissolved organic C was 98%, 128%, 145%, 175%, and 179% greater 29 months after application of 0, 40, 80, 120, and 160 Mg compost/ha, respectively, than before application. Rate of compost application had less effect on DOC than TOC, as DOC concentrations appeared controlled in part by bermudagrass growth patterns. Soil NO3-N was generally unaffected by compost application rate, as NO3-N decreased similarly for unamended soil and all compost treatments. Soil extractable P initially increased after compost application, but increasing the application rate generally did not increase P from 3 to 29 months. Seasonal or cyclical patterns of TOC, DOC, and extractable P were observed, as significantly lower levels of these parameters were observed in dormant stages of bermudagrass growth during cooler months.
C.M. Baldwin, H. Liu, L.B. McCarty, W.L. Bauerle, and J.E. Toler
A 2-year greenhouse study was conducted at Clemson University, Clemson, S.C., in 2003 and 2004 to determine drought responses of six bermudagrass (Cynodon spp.) cultivars at four irrigation intervals. Cultivars selected from the 2002 National Turfgrass Evaluation Program Bermudagrass Trial were `SWI-1012', `Arizona Common', `Tift No.3', `Tifsport', `Aussie Green', and `Celebration'. Treatments included 5-, 10-, and 15-day irrigation intervals plus a control (irrigated daily). Volumetric soil water content (VSWC) and evapotranspiration (ET) rates were recorded every 3 days. Turfgrass quality (TQ) was observed weekly and root weight was measured at the end of a 6-week study. `Aussie Green' and `Celebration' produced the highest TQ rating (>7) at week 4 when watered daily. After 4 weeks of the 5-day irrigation interval, all cultivars showed unacceptable quality ratings (<7). However, `Aussie Green' and `Celebration' were able to maintain an acceptable TQ rating (7), compared to `Arizona Common' (5.1) and `Tift No.3' (5.8) at week 2 (5-day treatment). `Celebration' produced 114% and 97% greater root weight than `Tifsport' and `Aussie Green', respectively, when pooled across all irrigation treatments. At the 15-day irrigation interval treatment, six bermudagrass cultivars pooled together produced 78%, 22%, and 11% greater root weight vs. control, 5-day, and 10-day treatments, respectively. When pooled for all treatments, `Aussie Green' and `Celebration' VSWC was 5% and 7% lower than `Tift No.3', and ET rates were 26% and 30% greater than `Arizona Common'. Based on these results, irrigating bermudagrass in 5-day intervals should be carefully monitored.
Billy J. Johnson, Robert N. Carrow, and Tim R. Murphy
Field experiments were conducted to determine the effects of foliar iron (Fe) applied with postemergence herbicides on injury, color, and quality of `Tifway' bermudagrass [Cynodon transvaalensis Burtt-Davy × Cynodon dactylon (L.) Pers.]. Iron significantly decreased injury and improved quality and color of `Tifway' bermudagrass in conjunction with herbicide treatment. Turf injury was less for 4 to 18 days after the initial MSMA application when Fe was added. Injury was also less from sequential Fe treatment with MSMA + metribuzin (up to 4 days) and MSMA + imazaquin (from 4 to 10 days) compared to the respective herbicides applied alone. There was no difference in turf injury from Fe when imazaquin at 1.3 kg·ha-1 was applied as a single treatment. However, turf treated with Fe and two applications of imazaquin (9- to 10-day interval) recovered from herbicide injury faster than when treated only with the herbicide. Iron did not prevent immediate 2,4-D + mecoprop + dicamba injury to the bermudagrass, but did hasten turf recovery from injury at 26 days after treatment. With a few exceptions, `Tifway' bermudagrass quality was higher and color improved when Fe was added. However, injury expressed as loss of shoot density was not affected by Fe and only injury expressed as color loss was improved by Fe. Chemical names used: 3,6-dichloro-2-methoxybenzoic acid (dicamba), 2-[4,5-dihydro-4-methyl)-4-(1-methylethyl)-5-oxo-1H-imidazol-2yl]-3-quinolinecarboxylic acid (imazaquin), (±)-2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop), 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one (metribuzin), monosodium salt of MAA (MSMA), and (2,4-dichlorophenoxy)acetic acid (2,4-D).