Progress 01/01/07 to 12/31/07
Outputs
Data from the studies shown in Outcomes/Impacts section below have been distributed to various end-user groups at turfgrass conferences, highway roadside vegetation management meetings and at professional society meetings such as the Southern Weed Science Society. Results from the highway roadside study clearly show that Milestone VM (aminopyralid) is a viable alternative to Oust (sulfometuron) for broadleaf weed control on bermudagrass roadsides. Yellow nutsedge remains a widespread weed problem in fine turfgrasses; however, this research shows that this weed can be effectively managed in bermudagrass turf with several recently-registered herbicides.
Impacts
Dismiss (sulfentrazone) at 0.25 and 0.375 lbs. ai/a, Echelon (sulfentrazone + prodiamine) at 0.75 and 1.25 lbs. ai/a and Pennant (s-metolachlor) at 2.5 lbs. ai/a were applied to separate plots on March 9, 2007 and April 10, 2007 which corresponded to 0% and 35% bermudagrass (Cynodon dactylon) green-up, respectively. Both application dates were prior to yellow nutsedge (Cyperus esculentus)emergence. These herbicides did not provide acceptable season-long preemergence control of yellow nutsedge when applied to dormant or greening bermudagrass. Echelon at 1.125 lbs A/A had greater than 90% control three months after the March application (June rating), but fell below 70% control, minimally acceptable, by 4 months (July rating). No treatment had better than 80% control two months after the April application, and control diminished thereafter. In a separate postemergence study, Dismiss was applied at 0.125, 0.188, and 0.25 lbs. ai/a on June 25, 2007. Separate plots were
retreated at intervals of four weeks (July 23), five weeks (July 30), or six weeks (August 8) after the initial application. In another postemergence study, Dismiss at 0.25 and 0.375 lbs. ai/a, Monument (trifloxysulfuron) at 0.016 and 0.035 lbs. ai/a and Certainty (sulfosulfuron) at 0.035 and 0.059 lbs ai/a was applied as a single treatment only on July 7, 2007 or sequentially on July 7, 2007 and August 8. Effective season-long postemergence control of yellow nutsedge was achieved with Dismiss at 0.25 and 0.375 lbs. ai/a, Monument at 0.016 and 0.025 lbs. ai/a and Certainty at 0.059 lbs. ai/a. Herbicide rates and reapplication timing affected control longevity. When Dismiss was reapplied 28 days after the initial application, greater than 87% control was achieved for an additional 46 days. Control diminished for the same time interval when sequential applications were extended to five and six weeks after the initial application. Milestone VM (aminopyralid) at 0.0625 and 0.11 lbs. ai/a
and Oust (sulfometuron) at 0.012 lbs. ai/a was applied alone or tank-mixed with Accord (glyphosate) at 0.1875 lbs. ai/a on February 16, 2007 for broadleaf weed control on a bermudagrass roadside. No herbicide applied alone or tank-mixed controlled buckhorn plantain (Plantago lanceolata). Both rates of aminopyralid provided effective (>80%) and better control of vetch (Vicia sp.), annual sowthistle (Sonchus oleraceus), cat's-ear (Hypochoeris sp.), heartwing sorrel (Rumex hastatulus), Venus looking-glass (Triodanis perfoliata), and hairy fleabane (Conyza bonariensis) than Oust. Bermudagrass exhibited excellent tolerance to both Milestone and Oust.
Publications
- Czarnota, M. and T. Murphy. 2007. Controlling Florida betony in the landscape. Univ. of Georgia Coop. Ext. Serv. Circ. 867. 5 pages.
- Kline, W. N., J. A. Ferrell and T. R. Murphy. 2007. New herbicide products and developments for dogfennel control in pastures. Proc. South. Weed Sci. 60:133.
- Murphy, T. R. and W. N. Kline. 2007. Horsenettle and dogfennel control in a Piedmont pasture. Proc. South. Weed Sci. soc. 60:126.
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Progress 01/01/06 to 12/31/06
Outputs
Progress continues to be made in determining the tolerance of seashore paspalum to herbicides. In experiments conducted in 2005 and 2006, quinclorac (Drive) at 0.5 and 1X (0.42 and 0.84 kg/ha, respectively) rates were applied to newly-seeded and -sprigged seashore paspalum cv. Sea Spray. Application timings were 0, 21 and 42 days after seeding or sprigging. In 2005, quinclorac at 1X applied at the time of seeding was the only treatment that temporarily decreased the density of seashore paspalum during establishment. This treatment reduced density approximately 30% at 28 and 35 days after application (DAA). No effect on density occurred at > 42 DAA. Quinclorac did not affect seashore paspalum establishment in 2006. This research showed that quinclorac, an effective herbicide for crabgrass (Digitaria spp.) and certain other annual weeds, could be applied at the time of seeding or sprigging, as well as during "grow-in" of seashore paspalum. This information was forwarded
to BASF, the registrant of quinclorac, who has added this use and turfgrass species to the Drive herbicide label. Other experimental herbicides were also evaluated on seashore paspalum in 2006. Mesotrione (no trade name) applied at the time of sprigging or seeding seashore paspalum did not affect final establishment. Mesotrione slightly injured (<15%) and decreased (<50%) density on both newly-seeded and -sprigged seashore paspalum at 14 DAA. However, by 30 days after application seashore paspalum density and quality were equal to the untreated check. Future research on the tolerance of seashore paspalum is needed as this turfgrass species does exhibit acceptable tolerance to mesotrione. In additional studies established seashore paspalum exhibited excellent tolerance to carfentrazone (QuickSilver), F6011 (an experimental from FMC), sulfentrazone (Dismiss), and halosulfuron (SedgeHammer). In additional studies foramsulfuron (Revolver) and metsulfuron (Manor, Blade) were evaluated for
the postemergence control of various winter annual weeds. Effective control of henbit and common chickweed was achieved with foramsulfuron at 0.014 kg/ha and metsulfuron at 0.005 kg/ha. Additionally, this rate of foramsulfuron controlled annual bluegrass. Neither herbicide controlled rescuegrass. Trifloxysulfuron-sodium (Monument) at 0.018 and 0.028 kg/ha, sulfosulfuron (Certainty) at 0.04 and 0.06 kg/ha and sulfentrazone at 0.28 and 0.42 kg/ha were evaluated for postemergence yellow nutsedge control in common bermudagrass. Herbicides were applied on July 7, 2006 as a single application or on July 7 and August 6, 2006 as a repeat application. Herbicides and application sequences that controlled (> 80%) yellow nutsedge at 105 DAA were single applications of trifloxysulfuron-sodium at 0.028 kg/ha, and sulfentrazone at 0.28 and 0.42 kg/ha. Single applications of these herbicides were as effective as repeat applications at 105 DAA. Repeat applications of sulfosulfuron at 0.06 kg/ha, and
trifloxysulfuron-sodium at 0.018 kg/ha were required for > 80% yellow nutsedge control at this same evaluation.
Impacts
Herbicides have been identified that will control emerged crabgrass, nutsedge and certain broadleaf weeds in established seashore paspalum. Additionally, turfgrass managers can now effectively control crabgrass with postemergence applications of quinclorac in newly-seeded and -sprigged seashore paspalum. The number of herbicides to control yellow nutsedge in bermudagrass continues to increase. With some herbicides, two applications will be required. However, one application of sulfentrazone can provide approximately 3.5 months of yellow nutsedge control.
Publications
- Ferrell, J. A., Murphy, T. R., Webster, T. M. 2006. Using Preemergence Herbicides to Improve Establishment of Centipedegrass (Eremochloa ophiuroides) from Seed. Weed Technology 20:682-687.
- Murphy, T. R. and F. C. Waltz. 2006. Seashore paspalum response to trinexapac-ethyl tank-mix combinations with flazasulfuron. Proc. South. Weed Sci. Soc. 59:104.
- Waltz. F. C., L. White and T. R. Murphy. 2006. Seashore paspalum response to trinexapac-ethyl tank-mix combinations with flurprimidol. Proc. South. Weed Sci. Soc. 59:103.
- White. L., F. Waltz and T. R. Murphy. 2006. Bermudagrass control in centipedegrass with triclopyr combinations. Proc. South. Weed Sci. Soc. 59:127.
- Warren, L. S., T. R. Murphy, T. W. Gannon and F. H. Yelverton. 2006. Dallisgrass control with MSMA and timings of sulfosulfuron and foramsulfuron. Proc. South. Weed Sci. Soc. 59:129.
- Murphy, T.R. and R. H. Walker. 2006. Efficacy of flazasulfuron for dallisgrass (Paspalum dilatatum) control in bermudagrass. Weed Sci. Soc. Am. Abstr. 46:15.
- Murphy, T. R. 2006. Key Pest-by-Pest Profiles and Critical Issues. Weeds, Algae and Mosses. In Pest Management Strategic Plan for Turfgrasses in the Southern United States. http://www.ipmcenters.org/pmsp/pdf/SouthernTurfgrass.pdf. pages 74-108.
- Waltz. C., G. Landry, T. Murphy, W. Hudson, and A. Martinez. 2006. Turfgrass pest control recommendations for professionals. Univ. of Georgia Coop. Ext. Ser. Bull. 984. (revised January 2005). 88 pages.
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Progress 04/01/05 to 12/31/05
Outputs
Seashore paspalum has a low requirement for fertilizer and is adapted to saline sites. Very few herbicides are registered for weed control in this species. Research conducted over the past four years has identified several herbicides that could be used for weed control in seashore paspalum. One herbicide that has shown outstanding potential for crabgrass control in seashore paspalum is quinclorac. This herbicide can be applied to established, newly-seeded and newly-sprigged seashore paspalum. Crabgrass is a major problem during establishment operations, and quinclorac will be a valuable herbicide to control this problem weed. A study was conducted to determine if flazasulfuron applied alone or tank-mixed with trinexapac-ethyl would regulate the vegetative growth and seedhead emergence of seashore paspalum. Treatments were applied on May 26, and again to the same plots on June 22 and July 20, 2005. Plots were mowed at a height of 1.25 cm and irrigated as needed. Data
collected included seashore paspalum injury, seedhead suppression from a non-mowed area of each plot and weekly clipping weights. Flazasulfuron and trinexapac-ethyl applied alone or as a tank-mix, and metsulfuron + trinexapac-ethyl did not adversely injure seashore paspalum. At most evaluations injury was < 15% for all treatments. Tank mixes of trinexapac-ethyl + flazasulfuron reduced clipping weights 33 to 56% more than flazasulfuron applied alone at the various evaluation intervals. With the exception of the 30 days after the first application (DAFA) evaluation, trinexapac-ethyl applied alone was as effective as trinexapac-ethyl + flazasulfuron and trinexapac-ethyl + metsulfuron tank-mixes in reducing clipping weights. Flazasulfuron at rates < 0.0088 kg/ha, trinexapac-ethyl and trinexapac-ethyl + metsulfuron did not effectively suppress (< 60%) seashore paspalum seedhead emergence. At 30 DAFA, flazasulfuron at rates > 0.0175 kg/ha provided > 80% seedhead suppression; however, at
subsequent evaluations suppression was < 70%. At 30 days after the second and third application, the addition of trinexapac-ethyl to flazasulfuron improved seedhead suppression over that obtained with flazasulfuron applied alone. Flazasulfuron at 0.026 or 0.052 kg/ha, and MSMA at 2.2 kg/ha applied alone or tank-mixed with flazasulfuron was evaluated for dallisgrass control in bermudagrass turf. Treatment sequences were a) flazasulfuron + MSMA applied in late May, followed by MSMA alone at 14 DAIA (days after initial application), and followed by flazasulfuron + MSMA at 28 DAIA, b) flazasulfuron + MSMA in late May and repeated again at 14 DAIA, c) MSMA in late May fb two applications of MSMA at 7 or 14 d intervals. Flazasulfuron at 0.026 or 0.052 kg/ha + MSMA fb MSMA fb flazasulfuron at shown rates + MSMA controlled dallisgrass > 85% at 105 DAIA. Control with two applications of flazasulfuron at 0.052 kg/ha + MSMA and three applications of MSMA applied at 7 or 14 d intervals controlled
dallisgrass < 60% at the same evaluation. Common bermudagrass injury was minimal (< 15%) for any treatment
Impacts
Information generated from this research is being supplied to agrichemical companies who have proprietary rights for these herbicides. Companies will be able to use this information to register these herbicides for use on seashore paspalum. The net impact will be that turfgrass managers and homeowners will soon have effective herbicides that can be used to control objectionable weeds in seashore paspalum.
Publications
- Murphy, T., Waltz., C., Ferrell, J. and S. Kammerer. 2005. Hybrid bermudagrass response to trinexapac-ethyl combinations with flurprimidol and paclobutrazol. Weed Sci. Soc. Am. Abstr. 45: 27-28.
- Burpee, L.L., Murphy, T.R. and J.R. Chamberlin. 2005. Bispyribac-sodium suppresses dollar spot (Sclerotina homeocarpa Bennett) in creeping bentgrass (Agrostis palustris Huds.). Weed Sci. Soc. Am. Abstr. 45: 102-103.
- Askew, S.D., Murphy, T.R., Willis, J.B., Ricker, D.B. and D.S. McCall. 2005. Relative downslope mobility of transition-assisting herbicides on overseeded bermudagrass (Cynodon dactylon) golf course fairways. Weed Sci. Soc. Am. Abstr. 45:28.
- Ferrell, J. A., T.R. Murphy and D. C. Bridges. 2005. Postemergence control of hybrid bermudagrass. Weed Technol. Vol. 19:636-639.
- Ferrell, J. A., T.R. Murphy, F. C. Waltz. Jr. and A.E. Smith. 2005. Oral and dermal exposure of golfers to 2,4-D, dicamba and mecoprop. Intern. Turf. Soc. Res. Journ. 10:1233-1239.
- Kammerer, S.J., T. R. Murphy and J. Ferrell. 2005. Effects of reduced rates and mixtures of trinexapac-ethyl, flurprimidol and paclobutrazol on bermudagrass growth quality and growth suppression. Intern. Turf. Res. Conference Tech. Papers 81-82.
- Murphy, T. R., J. Everest, J. Norsworthy, J. Green, F. Yelverton, G. Breeden, N. Rhodes and S. Hagood. 2005. Pasture and hay field weed management in the southeast United States. Proc. South. Weed Sci. Soc. 58:146.
- Kline, W. N. and T.R. Murphy. 2005. Aminopyralid: a new herbicide from Dow Agrosciences for selective broadleaf control in roadside vegetation management. Proc. South. Weed Sci. Soc. 58:267.
- Murphy, T.R. 2005. Response of seashore paspalum to foramsulfuron and flazasulfuron. Proc. South. Weed Sci. Soc. 58:107.
- Waltz, Jr., F. C. and T.R. Murphy. 2005. Turfgrass renovation with glyphosate. Proc. South. Weed Sci. Soc. 58:110.
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