for controlling grass weeds in creeping Smooth Crabgrass and Goosegrass Control bentgrass, new herbicidal control op- with Metamifop in Creeping Bentgrass tions would be beneficial for sustain- able management. Metamifop is an arloxyphenoxy- Ethan T. Parker1, J. Scott McElroy2, and Michael L. Flessner3,4 propionate (AOPP) herbicide that has reported herbicidal activity on smooth crabgrass and goosegrass ADDITIONAL INDEX WORDS. Eluesine indica, Digitaria ischaemum, Agrostis stolonifera, aryloxyphenoxypropionate with safety to creeping bentgrass. Metamifop is not currently registered SUMMARY. Smooth crabgrass (Digitaria ischaemum) and goosegrass (Eleusine in the United States, but is used for indica) are problematic weeds in creeping bentgrass (Agrostis stolonifera) because of POST annual and perennial weed limited herbicide options for postemergence (POST) control and turfgrass injury control in Asia and the Middle East. potential. Metamifop is a herbicide currently being considered for release to markets It is used in many turfgrass systems in the United States but information is lacking on the most effective rates and application timings for smooth crabgrass and goosegrass control in creeping including parks, golf courses, and bentgrass. Field trials were conducted in Auburn, AL in 2009 and 2013 to evaluate gardens (Flessner and McElroy, metamifop rates (200 to 800 gÁhaL1) and single or sequential application timings 2011; Hoyle et al., 2012; Kim et al., compared with fenoxaprop (51 to 200 gÁhaL1) at two different mowing heights. 2003a, 2003b; Post and Askew, Metamifop applied twice and three times sequentially at 200 gÁhaL1 provided the 2010). It is also used in many cereal greatest smooth crabgrass (>97%) and goosegrass (>90%) control at rough (1½ crops such as rice (Oryza sativa) for inch) and green (1/8 inch) mowing heights without unacceptable creeping control of annual and perennial grass bentgrass injury at 56 days after initial treatment. All treatments caused <20% weeds at 100 to 200 gÁha–1 (Moon visible injury on creeping bentgrass at both mowing heights except the highest rate et al., 2007, 2010). Along with of metamifop. Smooth crabgrass control at the green mowing height was greater smooth crabgrass and goosegrass, than at the rough mowing height, especially at lower metamifop rates with a single application. metamifop has also controls over an- nual grass weeds such as barnyard- grass (Echinochloa crus-galli), while mooth crabgrass and goosegrass past research has shown fenoxaprop remaining less injurious to cool- are problematic weeds in creep- to cause stunting and stand reduction season grasses (Flessner and McElroy, Sing bentgrass in the transition in seedling tall fescue (Schedonorus 2011; Kim et al., 2003b; Post and zone, an area that rests between the arundinaceus), perennial ryegrass Askew, 2010). Post and Askew southern United States where warm- (Lolium perenne), and creeping bent- (2010) observed that metamifop at season grasses dominate, and the grass (Cudney et al., 1997; Dernoeden, 300 gÁha–1 controlled smooth crab- northern United States where cool- 1987; Neal et al., 1990). Herbicidal grass while causing <10% creeping season grasses thrive. These weeds are control options of smooth crabgrass bentgrass injury whereas comparable able to survive low mowing heights, and goosegrass in creeping bentgrass smooth crabgrass control with fenox- especially among cool-season grasses also include quinclorac, siduron, and aprop completely killed creeping (Busey, 2003; Callahan, 1986). As bensulide. However, previous research bentgrass putting greens. herbicide-resistant populations of has shown stunting, thinning, or foliar Metamifop inhibits acetyl-CoA smooth crabgrass (e.g., quinclorac) phytotoxicity to both mature and im- carboxylase (ACCase), the enzyme and goosegrass (e.g., prodiamine mature cool-season turfgrasses includ- that catalyzes the first step in fatty and pendimethalin) increase and as ing creeping bentgrass with varying acid synthesis for membranes and cell cultural control methods can be in- rates and application timings of many growth (Burton et al., 1987; Devine effective in cool-season grasses, new of these herbicides as well (Busey, et al., 1993; Focke and Lichtenthaler, herbicides will be needed to ensure 2003; Cudney et al., 1997; Dernoeden, 1987; Senseman, 2007). Like other future control (Busey, 2003; Callahan, 1987; Mueller-Warrant, 1990; Neal AOPP herbicides, metamifop does 1986; Hart et al., 2004; Heap, 2015; et al., 1990; Warren et al., 1989). not affect eudicotyledonous plants Mudge et al., 1984). Currently, only bensulide and oxa- because of limited activity against Several herbicides have been reg- diazon are explicitly registered for cytosolic, the prokaryotic ACCase istered for smooth crabgrass and preemergence (PRE) smooth crab- (Burton et al., 1987; Senseman, goosegrass control in cool-season grass and goosegrass control on creep- 2007). It has been hypothesized that turfgrass (King, 1990; Parker et al., ing bentgrass putting greens (PBI/ these differing activities of AOPP 1985). Fenoxaprop controls both Gordon Corp., 2009; Quali-Pro, herbicides in cool-season grasses and crabgrass and goosegrass; however, 2013). Given these limited options the selectivity observed among grasses
1Department of Plant Sciences, 2431 Joe Johnson Drive, University of Tennessee, Knoxville, TN 37996 Units 2Department of Crop Soil and Environmental Sci- To convert U.S. to SI, To convert SI to U.S., ences, 201 Funchess Hall, Auburn University, AL multiply by U.S. unit SI unit multiply by 36849 0.3048 ft m 3.2808 3Department of Plant Pathology, Physiology, and 9.3540 gal/acre LÁha–1 0.1069 Weed Science, Virginia Polytechnic Institute and 2.54 inch(es) cm 0.3937 State University, Blacksburg, VA 24061 25.4 inch(es) mm 0.0394 4Corresponding author. E-mail: [email protected] 70.0532 oz/acre gÁha–1 0.0143
• December 2015 25(6) 757 RESEARCH REPORTS may be because of an altered binding 400, and 800 gÁha–1, metamifop ap- nontreated control on a 0 (no con- site within the ACCase target enzyme plied in two sequential applications trol) to 100 (complete plant necrosis) (Senseman, 2007; Stoltenberg et al., on a 3-week interval at 200 or 400 scale. Creeping bentgrass injury was 1989). Irrespective of the specific gÁha–1, metamifop applied in three visually evaluated using a similar 0 to mechanism, metamifop appears to be sequential applications on 3-week in- 100 scale, with a score of 20 repre- safer to cool-season turfgrasses while tervals at 100 or 200 gÁha–1. Fenox- senting the maximum level of creep- offering comparable control to other aprop (Acclaim ExtraÒ; Bayer ing bentgrass injury considered herbicides currently marked for crab- Environmental Science, Research Tri- acceptable, similar to previous studies grass and goosegrass control (Cox and angle Park, NC) was included as (Johnson, 1995, 1996; Johnson and Askew, 2014; Flessner and McElroy, a standard comparison and applied Murphy, 1995). 2011; Kim et al., 2003a; Post and in three sequential applications on EXPERIMENTAL DESIGN AND Askew, 2010). a 3-week interval at 17 gÁha–1 (note ANALYSIS. Data analyses were per- The most efficacious rates and that these rates are below label rec- formed using PROC GLM (SAS ver- sequential application timings to ommendations). Smooth crabgrass sion 9.1; SAS Institute, Cary, NC). achieve smooth crabgrass and goose- control studies were initiated on 17 Data were subjected to analysis of grass control have not been estab- July, 10 Aug., and 25 Aug. 2009 for variance and effects were considered lished. In addition, creeping bentgrass the first experimental repetition and significant when P < 0.05. Subse- tolerance to metamifop at different 19 June 2013 for the second experi- quently, data were subjected to means mowing heights must be assessed. Re- mental repetition. In both 2009 and separation using Fisher’s protected search was conducted to evaluate meta- 2013, smooth crabgrass growth stage least significant difference (P < 0.05). mifop rates and sequential application was one to two tillers at the putting All model assumptions were confirmed. timings for smooth crabgrass and green height and three to five tillers at In all studies, treatment and rating goosegrass control compared with an the rough height at the time of initial date were considered fixed effects industry standard, fenoxaprop. The application. Smooth crabgrass con- whereas year was considered a ran- second objective was to evaluate trol and creeping bentgrass injury dom effect. creeping bentgrass injury associated data were collected 7, 14, 28, 42, with varying rates and application and 56 d after initial treatment Results and discussion timings of metamifop at two mowing (DAIT). Twenty-eight DAIT corre- SMOOTH CRABGRASS AT ROUGH heights. sponds to 7 d after second treatment, HEIGHT. Smooth crabgrass control 42 DAIT corresponds to 21 d after and creeping bentgrass injury data were Materials and methods second treatment, and 56 DAIT cor- pooled across years as the year by Field research was conducted at responds to 35 d after second treat- treatment interaction was not signifi- the Auburn University Turfgrass Re- ment or 14 d after third treatment. All cant (P > 0.05). All metamifop treat- search and Education Center in Au- treatments were applied at 30 gal/ ments resulted in smooth crabgrass burn, AL (lat. 32.34 N, long. acre with a handheld four-nozzle control greater than fenoxaprop at all 85.29 W) in ‘Crenshaw’ creeping boom [nozzles on 25-cm spacing rating dates (Table 1). Metamifop rates bentgrass that has been established (TeeJet TJ8002VS; Spraying Sys- totaling 400 gÁha–1 or greater resulted for greater than 5 years. Soil type was tems, Wheaton, IL)] to 1.5 · 1.5-m in ‡80% smooth crabgrass control 56 Marvyn Sandy Loam (fine-loamy, ka- plots. DAIT. These data were consistent with olinitic, thermic Typic Kanhapludult) Treatments evaluated for goose- those of Cox and Askew (2014), who with a pH of 6.0 and 1.1% organic grass control were metamifop applied found that 400 gÁha–1 resulted in 88% matter. All trials were irrigated as once at 200, 300, and 400 gÁha–1, and control at 8 weeks after treatment. Meta- needed to prevent drought stress. metamifop applied in two sequential mifop treatments applied sequentially at Three studies were conducted. Stud- applications on a 3-week interval at 3-week intervals offered greater and ies 1 and 2 evaluated smooth crab- 200 or 300 gÁha–1. Fenoxaprop was more prolonged control (at 56 DAIT) grass control and creeping bentgrass included as a standard comparison than those applied only once, with injury at two mowing heights—1/8 and applied once at 100 gÁha–1 and the exception of the highest rate of inch simulating a golf course putting in two sequential applications on a 800 gÁha–1. Fenoxaprop applications green and 1½ inch simulating a golf 3-week interval at 100 gÁha–1.Goose- resulted in <50% control of smooth course rough, respectively. Study 3 grass control studies were initiated on crabgrass. All treatments resulted in evaluated goosegrass control in creep- 29 June and 20 July 2009 for exper- <15% creeping bentgrass injury with ing bentgrass at 1/8 inch height. All imental run 1 and 24 July and 19 applications of 800 gÁha–1 (whether studies were conducted as randomized Aug. 2013 for experimental run 2. sequential or one time) resulting in complete blocks with a minimum of Goosegrass growth stage was mostly the greatest injury (Table 2). Cox and three replications per treatment and all (‡75%) two to three tillers at the Askew (2014) reported no injury to studies were repeated in-time in 2009 initial application for both experi- any cool-season turfgrasses (not includ- and 2013 as subsequently described. mental repetitions with the remaining ing creeping bentgrass) in studies, but TREATMENTS. Treatments evalu- plant at less mature growth stages. made no conclusions because of lack ated for smooth crabgrass control Goosegrass control was rated 7, 21, of replication. Overall, metamifop at were the same for both mowing 42, and 56 DAIT. 200 gÁha–1 followed by 200 gÁha–1 heights and were metamifop (SAH- MEASUREMENTS. Smooth crab- resulted in the most economical com- 001; Summit Agro International, grass and goosegrass control were bination of smooth crabgrass control Tokyo, Japan) applied once at 200, visually evaluated relative to the (>95% at 56 DAIT) and creeping
758 • December 2015 25(6) bentgrass injury (<15%) at the rough Table 1. Smooth crabgrass control comparing metamifop treatments and mowing height compared with fenox- fenoxaprop at simulated roughs mowing height of 1½ inch (3.81 cm) pooled aprop (<49% control at 56 DAIT). over experiments in 2009 and 2013 in Auburn, AL. SMOOTH CRABGRASS AT GREEN 14 DAITy 28 DAIT 42 DAIT 56 DAIT HEIGHT. At green mowing height, Herbicide Rate (gÁhaL1)z % control the year by treatment interaction was nonsignificant for smooth crab- Metamifop 200 65 65 59 64 grass control, so data were pooled Metamifop 400 75 83 82 80 across years. All metamifop treat- Metamifop 800 94 95 95 93 ments controlled smooth crabgrass Metamifop 200 fb 200 68 90 96 98 greater than fenoxaprop at all rating Metamifop 400 fb 400 92 96 100 100 dates (Table 3). All metamifop treat- Metamifop 200 fb 200 fb 200 81 92 97 98 ments resulted in >90% smooth crab- Metamifop 100 fb 100 fb 100 60 67 72 91 > Fenoxaprop 17 fb 17 fb 17 23 25 39 49 grass control 28 DAIT, 95% control x 42 DAIT, and ‡94% control 56 LSD(0.05) 28 16 11 5 DAIT. Fenoxaprop resulted in <75% LSD = least significant difference. zSequential treatments were applied on 3-week intervals; 1 gÁha–1 = 0.0143 oz/acre, fb = followed by. smooth crabgrass control throughout yDays after initial treatment. the trial. A single application of meta- xLSD with a 95% confidence interval. mifop at 800 gÁha–1 resulted in ‡18% creeping bentgrass injury between 7 and 42 DAIT, with complete recov- Table 2. Creeping bentgrass injury from metamifop at various rates and application regimes at simulated roughs mowing height of 1½ inch (3.81 cm) in ery by 56 DAIT (Table 4). The 2009 and 2013 in Auburn, AL. second application of 400 gÁha–1 in the sequential treatment resulted in 7 DAITy 14 DAIT 28 DAIT 42 DAIT L 17% creeping bentgrass injury. There- Herbicide Rate (gÁha 1)z % injury fore, there is risk of creeping bent- Metamifop 200 0 0 2 0 grass injury associated with higher Metamifop 400 1 0 4 3 rates of metamifop, especially at low Metamifop 800 13 13 12 10 mowing heights. Sequential metami- Metamifop 200 fb 200 0 0 6 7 fop applications resulted in similar Metamifop 400 fb 400 4 0 10 9 smooth crabgrass control with less Metamifop 200 fb 200 fb 200 3 0 4 2 creeping bentgrass injury compared Metamifop 100 fb 100 fb 100 0 0 3 0 with single applications. Based on Fenoxaprop 17 fb 17 fb 17 1 0 0 0 x these results, an effective regimen LSD(0.05) 5 NS 57 for smooth crabgrass control in LSD = least significant difference. a creeping bentgrass putting green is zSequential treatments were applied on 3-week intervals; 1 gÁha–1 = 0.0143 oz/acre, fb = followed by. three applications of 100 gÁha–1 (98% yDays after initial treatment. xLSD with a 95% confidence interval; NS = not significant. control at 56 DAIT and 3% injury at 56 DAIT) or a single application of 200 gÁha–1 (94% control at 56 DAIT Table 3. Smooth crabgrass control comparing metamifop and fenoxaprop at and no injury at 56 DAIT). Similar to simulated greens mowing height of 1/8 inch (3.18 mm) pooled over this research, Post and Askew (2010) experiments in 2009 and 2013 in Auburn, AL. reported that metamifop controlled 14 DAITy 28 DAIT 42 DAIT 56 DAIT smooth crabgrass with <10% creeping L Herbicide Rate (gÁha 1)z % control bentgrass injury, whereas comparable smooth crabgrass control with fenox- Metamifop 200 93 96 96 94 aprop completely killed creeping Metamifop 400 99 100 99 96 bentgrass putting greens. Comparing Metamifop 800 99 100 99 96 this with creeping bentgrass mowed Metamifop 200 fb 200 92 96 98 99 at rough height, creeping bentgrass is Metamifop 400 fb 400 97 99 99 100 more susceptible to metamifop injury Metamifop 200 fb 200 fb 200 95 98 99 98 at lower mowing heights. Metamifop 100 fb 100 fb 100 86 91 99 98 GOOSEGRASS. Year by treatment Fenoxaprop 17 fb 17 fb 17 52 62 69 74 x interactions were not significant for LSD(0.05) 86710 goosegrass control studies; accord- LSD = least significant difference. zSequential treatments were applied on 3-week intervals; 1 gÁha–1 = 0.0143 oz/acre, fb = followed by. ingly, data were pooled. Metamifop yDays after initial treatment. –1 at 200 followed by 200 gÁha and xLSD with a 95% confidence interval. 300 followed by 300 gÁha–1 resulted in >89% goosegrass control 42 DAIT and 56 DAIT, respectively (Table 5). the best metamifop treatments (>90%). Metamifop applied sequentially at Fenoxaprop treatments resulted in These data indicate that metamifop 300 followed by 300 gÁha–1 does pose similar to significantly less goosegrass at 300 followed by 300 gÁha–1 was the injury risk to creeping bentgrass control at 56 DAIT (<74%) relative to best treatment for goosegrass control. greens, therefore timing is important
• December 2015 25(6) 759 RESEARCH REPORTS
Table 4. Creeping bentgrass injury from metamifop at various rates and application regimes at simulated greens mowing height of 1/8 inch (3.18 mm) in Literature cited 2009 and 2013 in Auburn, AL. Burton, J.D., J.W. Gronwald, D.A. 7 DAITy 14 DAIT 28 DAIT 42 DAIT 56 DAIT Somers, J.A. Connelly, B.G. Gengenbach, L and D.L. Wyse. 1987. Inhibition of plant Herbicide Rate (gÁha 1)z % injury acetyl-coenzyme A carboxylase by the Metamifop 200 1 0 1 0 0 herbicides sethoxydim and haloxyfop. Metamifop 400 9 3 6 1 0 Biochem. Biophys. Res. Commun. Metamifop 800 22 23 18 19 1 148:1039–1044. Metamifop 200 fb 200 0 0 0 5 3 Busey, P. 2003. Cultural management of Metamifop 400 fb 400 9 4 7 17 8 weeds in turfgrass: A review. Crop Sci. Metamifop 200 fb 200 fb 200 4 1 2 6 4 43:1899–1911. Metamifop 100 fb 100 fb 100 2 0 1 0 3 Callahan, L.M. 1986. Crabgrass and Fenoxaprop 17 fb 17 fb 17 5 0 0 1 0 x goosegrass control in a bentgrass green in LSD(0.05) 63 6 4NS the transition zone. Agron. J. 78:625–628. LSD = least significant difference. zSequential treatments were applied on 3-week intervals; 1 gÁha–1 = 0.0143 oz/acre, fb = followed by. Cox, M.C. and S.D. Askew. 2014. Met- yDays after initial treatment. amifop rates, application timings, and x LSD with a 95% confidence interval; NS = not significant. broadleaf herbicide admixtures affect smooth crabgrass control in turf. Weed Technol. 28:617–625. Table 5. Goosegrass control from metamifop at various rates and application Cudney, D.W., C.L. Elmore, V.A. regimes in 2009 and 2013 in Auburn, AL. Gibeault, and J.S. Reints. 1997. Common 7 DAITy 21 DAIT 42 DAIT 56 DAIT bermudagrass (Cynodon dactylon) man- L agement in cool-season turfgrass. Weed Herbicide Rate (gÁha 1)z % control Technol. 11:478–483. Metamifop 200 33 63 50 57 Dernoeden, P.H. 1987. Tolerance of pe- Metamifop 300 42 72 68 73 rennial ryegrass and tall fescue seedlings to Metamifop 400 45 76 75 81 fenoxaprop. Agron. J. 79:1035–1037. Metamifop 200 fb 200 34 58 89 91 Metamifop 300 fb 300 31 81 99 100 Derr, J.F., T.J. Monaco, and T.J. Sheets. Fenoxaprop 100 39 60 52 40 1985. Response of three annual grasses to Fenoxaprop 100 fb 100 38 58 87 74 fluazifop. Weed Sci. 33:693–697. x LSD(0.05) 8171014Devine, M., S.O. Duke, and C. Fedtke. LSD = least significant difference. 1993. Physiology of herbicide action. zSequential treatments were applied on 3-week intervals; 1 gÁha–1 = 0.0143 oz/acre, fb = followed by. Prentice Hall, Englewood Cliffs, NJ. yDays after initial treatment. xLSD with a 95% confidence interval. Flessner, M.L. and J.S. McElroy. 2011. Potential use of metamifop for weed control in turfgrass. Proc. Amer. Soc. Agron./Crop Sci. Soc. Amer./Soil Sci. when choosing a second application crabgrass. Generally, metamifop ap- Soc. Amer. Intl. Annu. Mtg., San Antonio, date. An alternative is to apply 200 plied sequentially resulted in greater TX. Abstr. 328-6. followed by 200 gÁha–1, which pro- smooth crabgrass and goosegrass Focke, M. and H.K. Lichtenthaler. 1987. vides good goosegrass control with control and creeping bentgrass safety Inhibition of the acetyl-CoA carboxylase less injury potential to creeping bent- relative to single applications. POST of barley chloroplasts by cycloxydim and grass than fenoxaprop, as well as de- metamifop applications along with sethoxydim. Verlag der Zeitschrift fur€ creased cost in amount of product used. currently used PRE options such as Naturforschung. 42:1361. bensulide and siduron will allow for Summary greater smooth crabgrass and goose- Hart, S.E., D.W. Lycan, and J.A. Murphy. 2004. Use of quinclorac for large crab- Compared with current herbi- grass control with the added benefit grass (Digitaria sanguinalis) control in cide options for smooth crabgrass of multiple modes of action to de- newly summer-seeded creeping bentgrass and goosegrass control, metamifop crease the likelihood of herbicide (Agrostis stolonifera). Weed Technol. offers comparable control with less resistance in creeping bentgrass sys- 18:375–379. threat of cool-season grass injury tems. Multiple applications of meta- Á –1 Heap, I. 2015. The International Survey (Derr et al., 1985; Neal et al., 1990; mifoptotaling300to600gha will of Herbicide Resistant Weeds. 30 Sept. Warren et al., 1989). Metamifop can provide good control of smooth 2015.
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