• The Effects of Pre-Emergence Applications of Sulfentrazone Herbicide and Perennial Ryegrass Overseeding of Poa annua Infestation of Winter Turf under Desert Conditions

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Poa annua or annual bluegrass is a cosmopolitan winter annual weed in turfgrass systems. A field test was conducted to evaluate the effects of sulfentrazone herbicide, both with and without the fall overseeding practice on bermudagrass in the desert. Sulfentrazone was applied three days before overseeding at 0.125, 0.187, 0.25, 0.375, 0.5 and 0.625 lbs.AI/A. Percent Poa infestation levels were dramatically less on overseeded (perennial ryegrass added) turf throughout the entire test period than non-overseeded (dormant bermudagrass) turf. For non-overseeded turf, sulfentrazone provided a maximum of 74% weed control at November 1997, 68% in December, and 25% by March 1998 at the highest application rate of 0.625 lbs./A. For overseeded (perennial ryegrass) turf, the highest level of weed control was achieved for sulfentrazone at the 0.625 lbs./A rate, which was 68% in April. The practices of overseeding and sulfentrazone applications provided the greatest weed control, however, different rate/timing regimes should be investigated to increase efficiency.
    • Ethephon Potential for Spring Transition of Perennial Ryegrass back to Common Bermudagrass

      Kopec, David M.; Jensen, D. P.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Spring transition of ryegrass back to the underlying bermudagrass has become problematic for turfgrass managers in the Southwest. This is in part do to increased heat tolerance and shoot densities of newer ryegrass cultivars which predominate the market place. The chemical ethephon (Proxy for turf) was evaluated for use as a plant growth regulator (PGR) to enhance transition from perennial ryegrass to bermudagrass. Proxy was applied at either 5 or 10 ounce rates/1000 square ft, either before, during or after soil moisture stress was imposed on the overseeded turf. On the dates of July 6, 21, 19 and August 9 the greatest visible difference occurred among treatments for percent bermudagrass. These responses were not not statistically significant, however. The greatest transition response was achieved (in general) from Proxy applied at 10 the ounce rate, when applied "pre-stress". This treatment combination generally ranked highest for percent bermudagrass throughout the test. The second most beneficial treatment (in general) was that of Proxy at the 10 ounce rate when applied under "medium stress". From July 21 to August 9 this treatment essentially ranked second for the ryegrass to bermudagrass transition. The third most beneficial treatment (in general) was Proxy applied at the 10 ounce rate , applied "post stress". This treatment was applied the latest in the season ( June 16), which was 22 days after the entire test was fully irrigated (at the start of the test on May 23). Proxy applied "post stress" at the 10 ounce rate excelled in enhancing the ryegrass to bermudagrass transition from July 21 to July 29. When applied at either the 5 or 10 ounce product rates, the "low stress" application treatments had minimal affect for transition. These treatments ranked similar in response to that of the untreated - well watered controls. The "medium" stress plots receiving Proxy exhibited a greater affect on the ryegrass to bermuda transition, depending on the date of bermudagrass evaluation. Further testing should be conducted on lower mowed perennial ryegrass with a more aggressive underlying bermudagrass base, such as the popular Tifway 419.
    • Evaluation of Proxy and Primo for Growth Reduction in Perennial Ryegrass

      Kopec, David M.; Jensen, D. P.; Liddell, Steven B.; Gilbert, Jeffrey J.; Marcum, K. B.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      PROXY (ethephon) and PRIMO (trinexepac-ethyl) were applied to ryegrass (as overseeded turf) in winter and early spring of 1999. PGR effect was assessed as reduction in clipping weight between mowings on eleven harvest dates. From March to April, the greatest percentage reductions were realized from all PGR treatments. Over the entire test period (March 5 to May 15), clipping reduction was rate dependent for PROXY with the 10.0 ounce rate producing a greater PGR effect (less clippings than that of PROXY at the 5.0 ounce rate). PRIMO treated turf (at the highest label rate of 1.0 ounce/product/1000 ft) generally produced the greatest clipping reductions, but lost affect in the middle of May when suppression (broke) was released. PROXY at the 10.0 ounce rate was closer to that of PRIMO for PGR effect than was PROXY at the 5.0 rate. All treatments produced less clippings than that of the control on nine of the eleven harvest events. PRIMO produced on average a noticeably darker color turf than PROXY treated turfs and that of the control plots as well. PROXY treated turf at the 10.0 ounce rate generally had similar overall quality turf when compared to PRIMO treated turf throughout the test. This was due to a high degree of plant uniformity among PROXY treated turf, versus the darker color enhancement realized from PRIMO. No PGR affected the initial stages of spring transition from ryegrass to bermuda by late May 1999.
    • Evaluation of Timing Applications of Ethephon and Trinexepac-Ethyl for Seed Head Suppression of Poa annua

      Kopec, David M.; Gilbert, Jeffrey J.; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Seed head production from Poa annua is problematic on winter turfs, whether they are overseeded or not. Flowering culms are unsightly, prevent a uniform surface, and insure a continuous crop of seeds for the future. A field test was conducted to evaluate the effects of PROXY and a PROXY/PRIMO PGR tank mix for seed head control. Treatments were applied on three different dates in order to evaluate the degree of response of treatments and help define treatment window applications for future programs. PROXY when applied alone at 5 ounces/product/M produced a maximum of 60% seed head control at 26 days after a single application on February 15, and 83% seed head control at 27 days after a single application on March 1. A tank mix of PROXY/PRIMO (5.0/0.25 ounces/product/M) generally produced greater seed head control than PROXY alone. The tank mix produced seed head control effects quicker, greater, and longer than PROXY alone. Seed head suppression and percent seed head control was greatest when products were applied initially on either February 15 or March 1, 2001. PROXY/PRIMO produced the darkest color turf when applied on either February 15 or March 1. At least three tank mixes seem to be needed, applied monthly to suppress/control seed heads throughout the winter/spring season.
    • Fairway Overseed Turfgrass Trials, 1996-1997 Season

      Kopec, David M.; Gilbert, Jeffrey J.; Kerr, Darren E.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Twenty-three overseed entries (and a non-overseed check) were evaluated from November 1996 to June 1997 for turf performance over Tifgreen (328) bermudagrass. Entries varied for turfgrass establishment, color, quality, density, texture and uniformity on all evaluation dates. One annual ryegrass and three intermediate ryegrass Lolium hybridium entries were included. The intermediate type 'Hybrid X-NC' had better performance than 'Froghair' or 'Hybredium' intermediate hybrids in most cases, except for early transition. Entries which consistently had the darkest green genetic color included 'Citation III', 'LPQ-N3', 'EP-20', 'Charger II', '84-91', 'WX-140', and 'Roadrunner'. Entries which consistently ranked high in overall turfgrass performance included 'Citation III', '2-DLM', '84-91', 'Roadrunner', 'Charger II', 'WX-140', '93-7', and 'LPQ-N3'.
    • Field Performance of Selected Mowed Distichlis Clones, USGA Research Report #1

      Kopec, David M.; Marcum, Kenneth P.; Hughes, Harrison; Christiansen, Dana; Koski, Anthony; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Twenty-one clonal selections of saltgrass (Distichlis) were evaluated in March and May for initial green-up, plot growth, unmowed canopy height, number of satellite plants emerging from rhizomes and floral expression. Accessions were statistically different for all variables measured. Colorado’s accessions (5 of 7) were upright in growth habit and had the greatest number of satellite plants at the surface in March. These plants also had the greatest percent plot coverage. Arizona’s accessions had lower growth in height, were more compact in growth and were less sprawling. However, their plot coverage (grow-in) was not as great as the upright, rapid growing Colorado accessions. Of the twenty-one clones included, thirteen are males and eight are females, with expression ranging from 1 to more than 200 flowering culms per plot.
    • Field Performance of Selected Mowed Distichlis Clones, USGA Research Report #2

      Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Twenty-one clonal selections of saltgrass (Distichlis spp.) were evaluated during the first full summer growing season (May - October 1999) for turf characteristics and general adaptation. Initial percent plot cover in May ranged from 8% to 42% among clonal accessions. Accessions which produced the highest unmowed canopy heights had the greatest initial cover in May. This trend reversed itself by August and September whereby entries which exhibited less elevated foliage tended to produce turfs which had higher shoot densities, greater percent plot cover, visual estimates of density and more acceptable overall turfgrass quality under accumulated mowing pressure. The "treatment" (clonal accession) affect was significant on all dates for all field variables demonstrating clearly that differences exist for growth parameters of Distichlis screened under mowing stress.
    • Field Performance of Selected Mowed Distichlis Clones, USGA Research Report #3

      Kopec, David M.; Adams, Alan; Bourn, Chris; Gilbert, Jeffrey J.; Marcum, Kenneth P.; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Twenty-one clonal (genotype) accessions of Distichlis are being continually evaluated for field performance as replicated mowed turf plots under desert conditions. The genotype ("treatment") affect was significant for most field variables measured, or assigned to plots using visual rating scales customary for turf evaluations. Genotype differences occurred for percent plot composition color, quality, texture, uniformity and leaf width. Visual stress (prolonged hot weather without irrigation) and leaf hair presence were not significant responses between accessions. Long term mowing stress shows divergent performance amount Distichlis germplasm for growth characters and turf persistence under mowed conditions.
    • Field Performance of Selected Mowed Distichlis Clones, USGA Research Report #4

      Kopec, David M.; Adams, Alan; Bourn, Chris; Gilbert, Jeffrey J.; Marcum, Kenneth P.; Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Clonal accessions (genotype selections) of Distichlis continue to show divergent responses for turf-type growth habit and general turf-type adaptation under field mowing stress. The treatment (clonal accession) affect was significant for all field response variables from mid July to mid August (data collections for Report #4, except for "percent plot straw" on October 12. In July 2000, mean percent plot green cover ranged from 47% to 96% among clonal accessions. Turfgrass quality in July was best among the entries A138, A86, A137, A48, A51, and A40. These entries had the greatest percent plot cover, moderately fine leaf texture, and high shoot density, compared to other entries. In the calendar year 2000, (includes weather conditions in Report #3), the test site was exposed to atmospheric conditions which included a reference ET. of 3.59" (January); 4.42" (February); 6.23" (March); 8.96" (April); 11.32" (May); 9.08" (June); 9.31" (July); 7.53" (August); 7.37" (September); 3.55" (October). The test was subjected to severe drought conditions throughout the test, starting April 2000. Rainfall from January too, and including April was 1.28 inches. There was no rain from May 1 to June 15. Four rains from July 17 to July 30 added 2.94 inches of rainfall, with two thirds of this occurring from one storm on July 29. No irrigation was added from July 1, until September 15. During that time period, 3.26 inches of rain fell in July. In August, 2.47" of rainfall occurred. From June 1 to September 15, the accumulated reference ET. was 29.68 inches. Total rainfall was 5.81" (no irrigation practiced). Most (but not all) Distichlis accessions maintained adequate turf color and percent plot green, up to late August. Visual stress ratings in early August showed differences in visual stress ratings and leaf canopy temperatures measured with a hand held IRT device. Entries A48, A51, A40, A138, A61, and C10 exhibited the least amount of visible drought stress in early August. Accessions that had the highest overall quality ratings in July were A138, A86, A137, A48, A51, and A40. Accessions that exhibited acceptable (highest) turf quality prior to and during the drought period included A138, A40, and A51. Drought induced dormancy finally occurred at the beginning of September, as most accessions drastically decreased the amount of green plot foliage after a prolonged period without irrigation. After flood irrigation and fertilizer applications on September 15 and September 29, plots recovered by mid October. The recovery was not full, as the greatest amount of green percent plot cover ranged from 23% to 83% among entries. Entries with the greatest amount of green cover after the post dormancy period included, A65, A138, A137, A77, and A72. All entries did exhibit reduced quality in comparison to July ratings. Based on these results, Distichlis should be irrigated once/month in a desert condition to avoid drought induced dormancy. During the calendar year 2000, accessions which had notable performance included: Early Spring Green Up: C8, A77, A138, A86; Early Summer Quality (non-water stress in May, and water stressed in June): A55, A86, A51, and A40, A138; Mid Summer Quality: A48, A86, A137, A51, A138; During Drought Quality: A138, A40, A51; Post Dormancy Quality: A65, A138, A137, A77, A72.
    • Forced Transition of Tifway 419 using Select Cultural Management Practices

      Kopec, David M.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      A test was devised to investigate a forced spring transition from perennial ryegrass, back to Tifway (419) bermudagrass with scalping as the main treatment. Scalping of the turf was combined with various nitrogen and aerification treatments performed initially on May 22, 1997. Turfgrass aeration, either with or without extra nitrogen applications, when combined with an initial scalping operation, did not enhance bermudagrass transition by twenty-eight days after treatment (DAT), at the end of June 1997. Turfgrass color, quality and density were adversely affected from initial aerification treatments, especially when combined with initial scalping, The turf recovered best from multiple applications of nitrogen (applied at scalping and again at 7DAT). Turfgrass density (visual estimates) showed that in conjunction with scalping, two applications of nitrogen, totaling 1.5 lbs./month, without aerification, provided a dense turf at 16DAT, which was second only to the untreated control plot. At 27 DAT, scalping + N + N + aerification treated plots had the highest estimate of visual density, eventually showing a benefit from aerification. Scalped and aerified turf alone (no nitrogen) had unacceptable turf density at 16DAT and 27DAT. Generally, two 0.75 lb./N/m applications with aerification proved beneficial over the single application of nitrogen plus aerification, when both turfs were initially scalped. Although non-significant statistically, the additional treatment of nitrogen provided 10% more bermudagrass cover than the single application of nitrogen, for turfs both overseeded and scalped. Scalping alone, plus a single application of N, produced 33% less bermudagrass by June 30, then that of the untreated control.
    • Green-Up of Dormant Bermudagrass after Applications of Early Spring Pre-Emergence Herbicides

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Six treatments of pre-emergence herbicides were evaluated for their effects on the spring green-up of dormant non-overseeded bermudagrass turf. Plot composition (percent yellow, percent green, percent straw or dormant turf) components were affected by herbicides to various extents on March 27, April 20, and April 27. Percent plot yellow turf was least in occurrence for BARRICADE, PENDULUM, and SURFLAN at 25 days after the first treatment. At 25 days after the first application (March 27) PENDULUM produced the lowest amount of green turf (13%) among treated turfs. At 50 days after the first application (April 20) PENDULUM treated turf had the greatest amount of yellow turf (63%), and the least amount of green turf present (18%). Turfgrass color was affected by herbicide treatments (on June 2, 30 days after the second treatment). The TEAM-PRO product had the darkest noticeable turf at this time. Herbicides had no affect on: A) visual estimates of turfgrass density B) number of lateral (horizontal) green stolons in the turf mat C) number of subterranean rhizomes D) root pegging of surface stolons. Green-up responses were short-lived from the herbicides evaluated at product rates tested.
    • Growth Responses of Desert Saltgrass under Salt Stress

      Pessarakli, Mohammed; Marcum, K. B.; Kopec, David M.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Saltgrass (Distichlis spicata), clonal accession WA-12, collected from Wilcox, Arizona was studied in a greenhouse to evaluate its growth responses in terms of shoot and root lengths, shoot fresh weight, and shoot and root dry weights under control and salt (sodium chloride) stress conditions. Plants were grown under control (no salt) and three levels of salt stress (100, 200, and 400mM NaCl equivalent to 6250, 12500, and 25,000 g Lᴮ¹ sodium chloride, respectively), using Hoagland solution in a hydroponics system. Plant shoots (clippings) were harvested weekly, oven dried at 60 °C, and dry weights recorded. At each harvest, both shoot and root lengths were measured and recorded. At the last harvest, plant roots were also harvested, oven dried, and dry weights were determined and recorded. The results show that the shoot and root lengths decreased with increasing the salinity levels, however, both shoot fresh and dry weights significantly increased at 200mM NaCl salinity compared with the control or the 400mM NaCl level. Root dry weights at both 200mM and 400mM NaCl salinity levels were significantly higher than the control.
    • Influence of pH 11 Water on Termiticide Degradation in Arizona

      Baker, Paul B.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Termites continue to be Arizona’s number one urban pest. Factors that influence the persistence of termiticides are constantly under investigation. High pH has been identified as a potential concern for persistence in termiticides. I studied the influence of pH 11 water on five termiticides applied to commercial ABC fill 10 months post-treatment. In general, the addition of pH 11 water had little influence on termiticide persistence under Arizona conditions. Initially plots treated with Ph 11 water had higher residues than those that did not receive the treated water; over time these differences diminished.
    • Initial Investigations of Effectiveness of Cultural Practices to Minimize the Negative Effects of Excessive Thatch on SR1020 Creeping Bentgrass

      Whitlark, Brian S.; Jensen, David; Kopec, David M.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Increased demand for golf course greens with fast ball speeds and aesthetically pleasing turf present the greatest public pressures that golf course superintendents face today. In the desert southwest, the annual summer monsoon rainfall pattern brings increased atmospheric humidity which results in an increase in the tendency of SR1020 creeping bentgrass to build-up thatch. The effects of four different cultural practices on color, quality, thatch, and ball roll were evaluated on a SR1020 creeping bentgrass green built to USGA specifications grown in an arid environment during a period of increased atmospheric humidity and rainfall. Plots that were verticut/topdress once every two weeks showed unacceptable color, quality, and ball roll. Rolling twice a week had no significant impact on color, quality, and thatch, however, rolling did have a slightly positive impact on ball roll. Grooming three times per week had no significant impact on thatch reduction, and resulted in decreased color, quality and ball speed. Topdressing one time per week did decrease the natural tendency of thatch build-up in SR1020 during periods of increased atmospheric humidity. Topdressing one time per week slightly increased color, quality, and ball roll.
    • Overseed Greens Trial 1997-1998

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Perennial ryegrass germplasm was quicker to establish plot cover on a "Tifgreen" bermudagrass green than that of Poa trivialis when used alone. Poa trivialis alone produced lighter color turfs when compared to perennial ryegrass. Turfgrass color was generally uniform in appearance, however, within each entry. Therefore, color as a selection criteria is a matter of choice by the user. The turfgrass mixture "Catalina/Winterplay" (80% perennial ryegrass/20% Poa trivialis) was intermediate in turfgrass color. "Brightstar II" PR generally produced a dark turf throughout the growing season. For overall turfgrass quality, the perennial ryegrasses generally out performed the Poa trivialis germplasm. The mixture of "Catalina/Winterplay" produced a very dense turf, followed closely by "Turfstar Plus" PR, "95-1" PR and "PT-4" PT. ASnowbird@ PT had the least amount of living ground cover by May 31, which is desirable from a transition standpoint.
    • Overseeding Fairway Trials

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Fifty-one overseed entries were evaluated in 1997-1998 for turfgrass performance. New experimental accessions of perennial ryegrass were darker in color than most of the commercially available germplasm included in this test. Ryegrass germplasm had better turfgrass quality after April, than did mixtures of perennial ryegrass with Poa trivialis, which performed well in December, January and March. General appearance for total plot leaf texture was best generally among the Poa trivialis containing mixtures. Hybrid (or intermediate) ryegrasses (L. which are crosses between perennial X annual ryegrass, are generally closer to annual ryegrass in performance. There was a vast improvement in L. hybridum (Pick YNC) when compared to annual ryegrass alone for turf performance. Intermediate and annual ryegrasses did show signs of decline in June (more so than ryegrass or Poa trivialis blends), which was desirable from a transition standpoint.
    • Oxadiazon Applied as a Pre-Emergence for Poa annua with Reference to Fall Overseeding of Bermudagrass Turf

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Ronstar was applied at three rates (1.0, 2.0 and 4.0 lbs. AI/A) at 12, 10, 8, 6 and 4 weeks before overseeding bermudagrass turf with perennial ryegrass on October 20, 1997. On November 7, 1997 (18 DAS) Ronstar treated plots ranged from 20% to 81% for percent plot ryegrass coverage. The greatest mean ryegrass coverage occurred for the 2.0 lbs. rate/@ 12 WBOS. Among the 4 lbs. treatments, there was more or less a linear decrease for ryegrass establishment on a visual plot basis as the application time came closer to the overseeding date. On December 1, Ronstar treated field plots ranged from a low of 29% ryegrass cover (4 lbs./@ 4 WBOS) to 91% (2 lbs./@ 12 WBOS). Among the 4 lbs. treated plots, the 10 and 12 WBOS timing allowed for 82% and 75% mean plot cover respectively, by December 1 (42 DAS). Of the remaining treatments, the 2 lbs./@ 4 WBOS had 61% plot cover (ryegrass) while all other 1 lbs. and 2 lbs. plots had 80% or greater cover at this time. On December 15, 1997 (56 DAS), mean percent plot scores for percentage ryegrass cover ranged from 53% to 100%. The only plot which had significantly less plot cover was 4 lbs./@ 4 WBOS (53%). All other plots had 88% or greater ryegrass cover. Turfgrass color scores showed a significant Atreatment@ effect on December 15, but not on December 29, January 29, March 11 or on April 11. On December 29 (70 DAS), overall turfgrass quality scores ranged from 4.0 (unacceptable) to 7.8. Two treatments which were sub-par included 4 lbs./@ 6 WBOS (5.7 = marginal) and 4 lbs./@ 4 WBOS (4.0 = unacceptable). Treatments which had mean quality values of 7.0 or higher included; 1 lbs./@ 10 WBOS (7.8), 1 lbs./@ 6 WBOS (7.8), 2 lbs./@ 10 WBOS (7.5), 1 lbs./@ 8 WBOS (7.3), 2 lbs./@ 6 WBOS (7.3), 4 lbs./@ 12 WBOS (7.3) and 2 lbs./@ 12 WBOS (7.3). Weed pressure was inadequate to fully assess pre-emergence control of Poa annua. At the close of the test on April 11, 1998, weed control ranged from 8% to 100%. Plots with 90% or greater weed control included 2 lbs./@ 10 WBOS, 1 lbs./@ 4 WBOS, and 4 lbs./@ 12, 8, 6, and 4 WBOS. The 1.0 lbs. AI/A treatment was safe for perennial ryegrass at 12, 10, 8, 6, and 4 WBOS. The 2.0 lbs. AI/A treatment was safe for perennial ryegrass at 12, 10, and 8 weeks. The 4.0 lbs. AI/A treatment was safe at 12 and 10 WBOS.
    • The Potential use of Sulfentrazone for Poa annua Pre-emergence Control at Overseeding

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Sulfentrazone herbicide was applied to bermudagrass turf, prior to overseeding at 0.125, 0.250 and 0.375 lbs. AI/A. Sulfentrazone did not inhibit emergence of perennial ryegrass when applied two days before overseeding. Plots ranged from 92-100% cover (of perennial ryegrass) from December to the end of March (last evaluation). Turfgrass color was noticeably less at the 0.375 lb. AI/A rate, but not significantly different from that of the lower rate application treatments. Pre-emergence weed control based on non-overseeded controls ranged from 51-100% across Sulfentrazone treated turfs, from December 1996 to late March, 1997. The percent reduction in Poa annua due to overseeding (comparison of non-overseed vs. overseed controls) was 90%, 61% 67% and 65% in December, January, February and March, respectively. Initial screening shows favorable activity for Poa annua control, especially at the 0.375 lb. AI/A rate. Further evaluation is needed to assess Poa annua suppression from Sulfentrazone and its potential interaction with overseeding, before cultural management programs can be devised for Poa annua control in an overseed program.
    • Response of Common Bermudagrass Turf to Applications of Sulfentrazone

      Kopec, David M.; Gilbert, Jeffrey J.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Sulfentrazone was applied in single applications at the rates of 0.125, 0.250 and 0.375 lbs. AI/A, and after 30 days in split rate combinations of 0.125/0.125, 0.250/0.250 and 0.125/0.375 lbs. AI/A. Turfgrass color scores were slightly diminished form sulfentrazone characterized by a lighter uniform color change on mowed common bermudagrass. The response was generally rate dependent. Imazaquin caused a light green turf to develop while halsulfuron had no effect. After the first application was made, sulfentrazone treated turfs exhibited leaf twisting/cupping effects at 3 and 7 days after treatment. The degree of effect was also rate dependent. To the lay person, twisting was noticeable only for a short time at the 0.375 lb. AI/A rate. At two weeks after treatment, there was a trace amount of leaf sheath necrosis at the base (older leaves) of common bermudagrass stolons. This was negligible and short lived. At the rates tested in this initial preliminary test, it appears that common bermudagrass seems to be tolerant of sulfentrazone.
    • Response of Creeping Bentgrass to Sulfentrazone Herbicide under Putting Green Maintenance Conditions

      Kopec, David M.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)
      Sulfentrazone herbicide was applied to a SR1020 creeping bentgrass putting green (5/32") on October 15, 1996 and again on March 4, 1997 at the rates of 0.125, 0.250 and 0.375 lb. AI/A. Betasan was included at the standard rate of 5.6 ounces of product/1000 ft2. Turf response to sulfentrazone was mostly linear with application rate, with higher application rates causing more damage to the turf. Responses occurred quicker in the fall (by 3 DAT) compared to late winter (7DAT). Magnitude of injury was also somewhat less in the late winter than in the fall, although rank responses were still rate dependent for sulfentrazone treated creeping bentgrass turf. Applied rates of 0.250 and 0.375 lb. AI/A were deleterious and not acceptable for putting green quality turf. A marginal (acceptable) response occurred overall at the 0.125 lb. rate. Betasan applied at 5.6 ounces product/1000 ft², caused no visible damage to the turf in the fall and was similar in response to sulfentrazone in the spring at the 0.125 lb. AI/A (repeat) application rate.