• Growth Responses and Nitrogen Uptake of Saltgrass under Salinity Stress

      Gessler, Noah; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Various saltgrass (Distichlis spicata) clones were studied in a greenhouse to evaluate their growth responses in terms of shoot and root lengths and shoot and root dry matter (DM) weights under salt stress. Plants were grown hydroponically using Hoagland solution No. 1. Treatments included control plants and plants grown with salt (NaCl) at EC of 20 dSm⁻¹. Twelve different clones were grown with four replications of each variety. Plants were grown in a randomized complete block (RCB) design. Plant shoots (clippings) were harvested weekly, oven-dried at 60° C and DM weights were recorded. At the last harvest, plant roots were also harvested, oven-dried at 60°C and DM weights were determined and recorded. The results show increased shoot length in control plants, increased root length in most of the plants grown in saline conditions, greater shoot dry weight in control plants and greater root dry weight in saline plants. All results for shoots are based on a weekly average for six weeks and for roots are based on an average of the four replicated clones at the end of the study.
    • Growth Responses of Selected Warm-Season Turfgrasses under Salt Stress

      Pessarakli, Mohammed; Kopec, David M.; Gilbert, Jeff J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Use of low quality/saline water for turf irrigation, especially in regions experiencing water shortage is increasing. This imposes more salt stress on turfgrasses which are already under stress in these regions. Therefore, there is a great need for salt tolerant turfgrasses to survive under such stressful conditions. This study was conducted in a greenhouse, using hydroponics system, to compare growth responses of three warmseason turfgrasses, bermudagrass (Cynodon dactylon L.), cv. Tifway 419, seashore paspalum (Paspalum vaginatum Swartz), cv. Sea Isle 2000, and saltgrass (Distichlis spicata L), accession A55 in terms of shoot and root lengths and DM, and canopy green color (CGC) under salt stress condition. Whole plants, stolons, and rhizomes were grown in Hoagland solution for 4 months prior to initiation of salt stress. Then, plants were grown for 12 weeks under 4 treatments (control, 7000, 14000, and 21000 mg/L NaCl) with 4 replications in a RCB design trial. During the stress period, shoots were clipped bi-weekly for DM production, shoot and root lengths were measured, and CGC was evaluated weekly. The bi-weekly clippings and the roots at the last harvest were oven dried at 60o C and DM weights were recorded. Shoot and root lengths and shoot DM weights decreased linearly with increased salinity for bermudagrass and paspalum. However, for saltgrass these values increased at all NaCl levels compared with the control. For bermudagrass and paspalum, the highest values were obtained when the whole plants were used, and the lowest ones resulted when the rhizomes were used. The reverse was found for saltgrass. For the control plants, the measured factors were higher and the canopy colors were greener for bermudagrass and paspalum compared with saltgrass. The canopy color changed to lighter green for bermudagrass and paspalum as NaCl salinity increased, but saltgrass maintained the same color regardless of the level of salinity.
    • Low Maintenance Overseed Trials 2007– 2008

      Kopec, David M.; Gilbert, Jeff J.; Pessarakli, Mohammed; Nolan, Steve; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Five hybrid ryegrasses were evaluated as low maintenance turfs against Gulf annual ryegrass an one turf-type perennial ryegrass, when mowed once a week at 2.75 inches. Among four improved hybrid ryegrass entries, several hybrid ryegrass entries did not statistically differ from the dark perennial ryegrass color as hybrid 05 ABL maintained dark color throughout the test from November 2007, to late April 2008. The entries 05 ABD, 04-1 LH and 04-2 LH all provided nominally dark color turfs, which held good color even up to the end of April. At a seed rate of 625 lbs PLS/acre, all entries produced acceptable "dense" turfs, with the exception of Gulf annual. The hybrids 05 ABL and 04-2 LH produced very dense turfs, with high apparent shoot densities very similar to that of perennial ryegrass. Both 04-1 LH and 0 5 ABD hybrids also produced satisfactory turf densities as well. While the perennial ryegrass "American Star" had very narrow leaves, the hybrid 04 2 LH also had fine leaves throughout the season. Hybrid 05 ABL was also fine textured. After emergence, 04-1 LH hybrid had somewhat wider leaves than some of the other hybrids, but it produced finer leaves shortly afterwards until the close of the test. Measured leaf widths ranged from 1.4 to 2.7 mm in February under peak performance conditions of growth and weather. American Star perennial ryegrass ranked highest for quality on most occasions, but was often included in the same statistical mean performance grouping (within the same LSD value range) with the hybrid entries of 04-2 LH, 04-1LH, 05 ABD, and 05 ABL. Froghair was generally better than Gulf annual in quality, while the check plots (nonoverseeded) showed green up by late April. At mid June, both Gulf annual and Froghair hybrid ryegrass had the least amount of overseed present, but the bermudagrass was not filling in quickly as other hybrids which had more bermudagrass cover present and less straw (from dead overseed) present. This was true for hybrids 05 ABL (41% bermuda: 13% straw), and 04-1 LH (25% bermuda: 11% straw). Therefore, there are hybrid entries which show better transition than Gulf annual, and at the same time produce lesser amounts of lingering necrotic tissue at transition.
    • Overseed Home Lawn Variety Trials 2006-2007

      Kopec, David M.; Gilbert, Jeff J.; Pessarakli, Mohammed; Nolan, Steve; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Spring transition (from ryegrass to bermudagrass) has been problematic for the last 20 years based on, in part, improved heat tolerance and lower growing cultivars of perennial ryegrass. Annual ryegrass is used sparingly for commercial properties and for home owners in southern Arizona. Hybrid ryegrass (cross between perennial and annual ryegrass) has been manufactured by seed companies in an effort to improve the transition of a grass used specifically for overseeding, with improved turf grass attributes over those of annual ryegrass. A field test was conducted to evaluate several hybrid ryegrasses, two improved annual ryegrasses, and Gulf annual ryegrass under homeowner conditions. The true annuals produced the quickest amount of ground cover in the shortest period of time. By early December, all plots had 98% or more cover, with FH having 95% cover. Transend, Transport and 041 Lh had consistently high quality scores throughout most of the 8 month test, with Transport and 04 1 LH scoring for fair turfgrass quality into mid June. Sprint annual ryegrass had excellent turfgrass quality scores in November and December, however, scores declined substantially in April and afterwards. After emergence and into early December, Transport and 041LH clearly had the darkest turf coloration, with 041LH producing a turf with a color intensity typical of medium green perennial ryegrass. Gulf and FH were noticeably lighter in color. Gulf, Sprint and Transcend developed ring/patch type disease symptoms in early February 2007, while others did not. "Stemminess" ratings in late spring (a time at which annual ryegrass is typically pronouncedly so) showed that FH intermediate and Gulf produced the most "stemmy" turfs, followed by Sprint annual. Transport and 041LH showed hardly any seed head culm development, with Transcend being intermediate. Interestingly, not all the entries which generally had the highest numerical rankings for density, texture, uniformity and overall turfgrass quality, had the highest percent plot living overseed during transition. Entry 041LH had 30% overseed, 46% bermuda, and 24% straw. Transcend had 16% overseed, 25% straw and59% straw on June 12. Transport had the highest retention of green overseed (72%), with 23% bermuda and 5% bare ground or straw plot cover. Sprint had 19% overseed, 20% live bermudagrass, and 61% bare straw plot cover, more so than that of Gulf. Final quality scores showed that 041LH and Transport had the best quality mean rank values, with all others having low quality scores on 12 June just prior to scalping to fully reconstitute the underlying Tifway bermudagrass. This shows vast improvements in turfgrass performance for INTERMEDIATES, which previously (and again) show near full acceptability in most turfgrass attributes, and now show enhanced color. Likewise, improvements in strict annual types show improved turf quality (Sprint) over Gulf.
    • Perennial Ryegrass Transition Using Selected Herbicides

      Kopec, David M.; Gilbert, Jeff J.; Nolan, Steve; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Thirteen herbicide treatments were applied on May 8, 2006, on a golf course fairway to assess transition and turf quality effects. Initial injury to perennial ryegrass was most extreme for Tranxit GTA when applied at 1.0 oz/prod/acre and Katana applied at 2.0 oz/prod/acre. Katana resulted in the total elimination of ryegrass and resulted in a fully necrotic canopy (straw cover) within two weeks after application to July 19, 2006 (72 Days after treatment). The development and persistence of necrotic leaf tissue of perennial ryegrass (straw) had the greatest impact on decreasing overall turfgrass quality ratings. No treatment went through the summer without some loss of quality at some point, including the untreated control. Certainty had little or no effect on transition when applied once at the rate of 1.25 oz/prod/acre. Surflan was not effective in ryegrass transition. The tank mix of Transit and nicosulfuron applied at the rate of 0.25 oz/prod./A each, produced an enhanced transition with nominal quality. In similar fashion, Monument applied at 0.35 oz./A produced an enhanced transition with nominal quality. A rates used in this test, other treatments had either too slow of a transition or had poor and extended low quality turf scores from rapid development of dead ryegrass (straw) and subsequent slow bermudagrass re-establishment. The UTC turf maintained a high percentage of living green ryegrass into the summer and 20% live ryegrass on August 8, 2006 which is roughly six weeks before the next overseeding.
    • Repeat Applications of Paclobutrazole (TGR) Plant Growth Regulator on Overseeded Bermudagrass Turf: Weed Control and Bermudagrass Transition

      Kopec, David M.; Gilbert, Jeff J.; Pessarakli, Mohammed; Nolan, Steve; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      TGR (paclobutrazole) was applied to both overseeded and non-overseeded turfs in repeat monthly applications at either 8.0 oz or 12.0 oz product/1000 ft² rates. Applications were made in repeat monthly intervals to apply either three, four or five repeat applications beginning in December 2007, and ending in April 2008. When applied as a post emergent PGR material, TGR caused only a slight decrease in turfgrass color and quality of overseeded turfs in March at the high (and repeated) rate of 12.0 oz/product/acre. This effect was short lived, as overseeded turfs for the remainder of the season maintained fully acceptable color and quality through the spring transition period. Tenacity turfs always had quality scores of 6.0 or higher throughout the test. Seed head suppression was realized from TGR, with greater head suppression at the 12.0 oz rate than that of the 8.0 oz rate. Bermudagrass transition among TGR treated turfs was not different from that of the untreated controls, whether the turfs were overseeded or not. On 20 June 2008, percent bermudagrass plot cover ranged from 29-58% for TGR treated turfs, 40% for Tenacity, while the overseeded UTC had 35%, on average. The percent bermudagrass increased quickly after a 2.0 lb. /N /M application on June 20, to 68% to 90% bermudagrass cover for TGR treated turfs (UTC = 83%). After a scalping event (from 1.25 inches to 0.50 inches) performed on July 1, percent bermudagrass decreased temporarily (from bermudagrass removal), but rebounded within 15 days to yield 96% to 99% bermudagrass cover by the close of the test on 31 July, 2008. Like wise, Tenacity alone did not inhibit transition, as Tenacity treated turfs had bermudagrass cover slightly greater than that of the overseeded controls.
    • Turfgrass Systems for Saline Irrigation Water

      Walworth, James; Kopec, David M.; Pond, Andrew; Gilbert, Jeff J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Seashore Paspalum (Paspalum vaginatum) is a warm-season halophyte with excellent salt tolerance after establishment. In areas which require overseeding, there is a need for a cool-season counterpart suitable for over-seeding. The goal of this field research is to evaluate a year-round turfgrass system for saline conditions using perennial ryegrass (Lolium perenne), alkaligrass (Puccinellia distans), and a combination of perennial ryegrass and Puccinellia as the cool-season grasses. In the summer months, paspalum quality and density were reduced when overseeded with ryegrass or with a combination of puccinellia and ryegrass. Ryegrass quality and density decreased slightly as irrigation water salinity was increased from 0 to 3000 to 6000 mg/L. In addition, the percentage of cover by overseeded ryegrass decreased significantly when 6000 mg/L irrigation water was applied. Puccinellia was much more sensitive to salinity than ryegrass and overall quality, turf density, and percent cover by puccinellia were greatly reduced by addition of salt. However, in the absence of added salt, puccinellia quality, percent cover, density, and color were generally greater than that of ryegrass. The puccinellia/ryegrass overseed mixture generally performed intermediate relative to either grass alone.
    • Use of Select Herbicides for Pre and Post Emergence Control of Poa annua When Overseeding Bermudagrass with Perennial Ryegrass

      Kopec, David M.; Gilbert, Jeff J.; Pessarakli, Mohammed; Nolan, Steve; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Overseeding bermudagrass turf with perennial ryegrass is essentially a standard practice in south western turfgrass maintenance. This practice complicates (and often negates) the pre-emergence control of Poa annua (PA) which germinates within the overseeding window. Outplay (mesotrione) was applies as pre , post and pre+post applications to control PA in golf turf (overseed on October 2, 2006). Outplay was applied with Trimmit as a post emergence treatment. Barricade and Barricade + Monument were applied post emergence. On non overseeded turf: The greatest amount of (PA) weed control was achieved by the treatment of Barricade 16 ounce/product/acre (8WBOS) and Monument 16 gm (2WBOS) (Table 3). This treatment had no PA initially (2 November) 93% control on 17 November, and 7 December, 90% control on 4 January, dropping to 77% control by 16 February. Outplay applied pre-emergence as a sole treatment had little or no affect on PA, providing essentially no control. This was even true for the high rate of 16 ounces of product, applied 1 week before overseeding. Outplay applied both pre/post at eight ounces also had little effect on PA. The same was true for Outplay applied as two post emergence treatments [( 8 + 8 ) or (16 + 16) ounce rates] (Table 3). Prograss had a maximum weed control of 50% on January 4, sixteen days after its repeat application of 64 ounce. The post emergence tank mix of Outplay and Trimmit, followed by Trimmit alone had a maximum of 50% (PA) weed control on January 4, which declined afterwards. Overseeded Turf: Barricade and Barricade plus Monument had good control initially (94% 16 February), noting that the addition of Monument increased percent weed control by 10% in March (Table 8). Outplay applied alone as a pre-emergence product, had minimal control, with the high rate of 16 ounces applied 1 week before overseeding providing nominal weed control (65%, 41%, 58%) on 16 February, 15 March, 26 March, respectively. Outplay applied as a post emergence treatment only, exhibited good to moderate weed control, with the 16 and 16 ounce repeat treatments having better weed control than the 8 ounce plus 8 ounce treatments (applied 8 weeks and 12 weeks after overseeding, respectively). The 16 and 16 ounce treatment had 100%, 82% and 78% weed control on 16 February, 15 March, and 26 March, respectively (Table 8). Prograss applied twice as a post emergence provided similar levels of PA control (100%, 85%, 89%) on those same dates, respectively. Finally, when Outplay was applied as a post emergence treatment with Trimmit, weed control was good to moderate, providing 88%, 67%, and 78% weed control on overseeded turfs on 16 February, 15 March, and 26 March, respectively (Table 8). The affect of overseeding itself based on NTC means of overseeding and nonoverseed turfs (no herbicides) showed that overseeding alone suppressed PA by 93% on 16 February, 91% on 15 March and 59% on 26 March.
    • Use of Velocity for Post Emergence Control of (AB) in Overseeded Turf

      Kopec, David M.; Gilbert, Jeff J.; Nolan, Steve; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Velocity herbicide was applied alone, or with mixtures of Tourney fungicide and/or Primo PGR for the post emergence control/suppression of Poa annua (var. annua) in bermudagrass overseeded with perennial ryegrass. When applied alone as a repeat applications, Velocity herbicide applied at 15 and 30 gm ai/a was safe on perennial ryegrass overseed (based on color response). Velocity was safe for the overseed ryegrass when tank mixed with Tourney fungicide, both with and without the addition of Primo PGR. Tourney fungicide when applied alone at either 8 or 16 oz./product/acre produced no negative affects. As expected, Primo alone produced a dark color turf (7.8, 7.5, 7.0, and 7.0) on all four dates, respectively. Several treatments caused moderate injury to the (AB) across the entire test period. These included Velocity alone at the 15 gm/ai/a rate, and Velocity @ 30 gm ai/a plus Tourney @ 8 oz.prod/acre. The greatest amount of injury to (AB) occurred on 3/11/2008 for Velocity at 30 gm ai/a, either with or without Tourney fungicide. Although visible injury to Poa annua resulted after treatments were applied, seed head suppression was the most consistent treatment response. While injury to the Poa was severe for some treatments (Velocity plus Tourney fungicide), the Poa annua did return, ranging from re-growth as "weak plants" to an actively growing turfs (as is sometimes typical after a surviving injury response). Based on results, perhaps a tank mix application of Velocity at 30 gm ai/a along with 8 oz. product/acre of Tourney and 6 oz./acre of Primo, followed by a repeat application 35 days later may provide the ultimate seed head suppression.
    • Velocity* Herbicide for Poa annua Control in Turf

      Umeda, Kai; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)
      Velocity* at 20 g a.i./A provided P. annua control better than at 10 g a.i./A. Velocity at 20 or 30 g a.i./A offered similar P. annua control with a single application. Velocity at 20 g a.i./A with the addition of non-ionic surfactant Latron CS-7* or Primo*, P. annua control was almost similar to that of Prograss* at 80%. Velocity at 10 g a.i./A combinations or at 20 g a.i./A without additives gave less than 75% control.