HORTSCIENCE 47(6):798–800. 2012. was applied 2 WBS (Lycan and Hart, 2006). Sulfosulfuron at 13 to 26 g/a.i./ha applied the day of seeding or 1 WBS reduced creeping Perennial Ryegrass and Tall Fescue bentgrass and kentucky bluegrass establish- ment compared with the non-treated control Reseeding Intervals after (McCullough and Nutt, 2010; Willis et al., 2007). Amicarbazone applied at 0.4 kgÁha–1 Aminocyclopyrachlor Application has the potential to reduce perennial ryegrass and tall fescue cover when applied the day John B. Workman1, Patrick E. McCullough2,4, and F. Clint Waltz3 of seeding. However, researchers noted that Department of Crop and Soil Sciences, University of Georgia, 1109 Experiment perennial ryegrass and tall fescue establish- Street, Griffin, GA 30223-1797 ment appears uninhibited when amicarba- zone at the same rate is applied 2, 4, or 6 James T. Brosnan2 WBS (McCullough et al., 2011). Common Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996 bermudagrass [Cynodon dactylon (L.) Pers.] seedlings have shown significant injury Gerald M. Henry2 and reduced establishment in response to Department of Plant and Soil Science, Texas Tech University, Lubbock, TX rimsulfuron, , and trifloxysulfuron applied 1 to 2 WBS (McCullough and Nutt, 79409-2122 2010; Willis et al., 2007). McCalla et al. (2004) Additional index words. establishment, turf, , weeds reported that ‘Princess 77’ bermudagrass seedlings exhibited 30% or less injury after Abstract. Turfgrass managers applying aminocyclopyrachlor for annual and perennial applications of diclofop, metsulfuron, 2,4-D, broadleaf weed control in cool-season turfgrasses may want to reseed into treated areas. , monosodium acid methanearsonate Field experiments were conducted in Georgia), Tennessee, and Texas to investigate (MSMA), , and applied perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) 1, 2, and 4 weeks after emergence. McElroy reseeding intervals after aminocyclopyrachlor applications. Perennial ryegrass and tall et al. (2005) noted that prepackaged mixtures fescue establishment were similar to the non-treated control after treatments of amino- of containing 2,4-D, , cyclopyrachlor and 2,4-dichlorophenoxyacetic acid (2,4-D) + dicamba + methylchlor- dicamba, clopyralid, or should be ophenoxypropionic acid (MCPP) at 0, 2, 4, or 6 weeks before seeding. Results used with caution when applied at seeding or demonstrate that no reseeding interval is required after aminocyclopyrachlor treatment. before stolon development with warm-season Perennial ryegrass and tall fescue can be safely seeded immediately after amino- grasses. The researchers found that low and cyclopyrachlor treatment at 39, 79, and 158 g/a.i./ha. high rates of 2,4-D + mecoprop + dicamba and 2,4-D + clopyralid + dicamba reduced ber- mudagrass cover of the cultivars Yukon, Synthetic are popular herbicides (Anonymous, 2010; Bukum et al., 2010; Riviera, and Princess 7 21 d after initial for selective, postemergence broadleaf weed Curtis et al., 2009; Rudenko, 2009). treatment when compared with the non- control in turfgrass management (Struckmeyer, Aminocyclopyachlor has promising im- treated control (McElroy et al., 2005). 1951; Watson, 1950). Herbicides in this class plications for controlling problematic broad- Turfgrass managers may need to reseed of chemistry control susceptible weeds by leaf weeds in turfgrass, but turfgrass managers desirable turfgrasses like perennial ryegrass disrupting hormonal balance leading to in- may want to re-establish cool-season grasses and tall fescue after broadleaf weeds have creased cell wall plasticity, nucleic acid metab- from seed after applications. Application been controlled by aminocyclopyrachlor or olism, and uncontrolled growth in meristimatic timing and rate of postemergence herbicides other postemergence herbicides. Thus, re- regions (Sterling and Hall, 1997). A new from various herbicide families have been seeding intervals may be critical for new synthetic , aminocyclopyrachlor, was reg- reported to inhibit establishment of cool- and herbicides introduced for postemergence istered in 2010 for annual and perennial broad- warm-season turfgrasses from seed. Prepack- broadleaf weed control in turf management leaf weed control in turfgrass (Anonymous, age products that include auxin herbicides regimes. Data describing reseeding intervals 2010). 2,4-D, dicamba, and MCPP are recommen- after aminocyclopyrachlor treatments are Aminocyclopyrachlor is the first pyrimi- ded to be applied 3 to 4 weeks before seed limited. In the transition zone and cool humid dine carboxylic acid herbicide with structural is sown or after two to three mowing events region of the United States, tall fescue and similarities to (Bukum et al., 2010). (Anonymous, 2004). Quinclorac, a highly se- perennial ryegrass are widely used for resi- This herbicide has both foliar and soil activity lective auxin herbicide, has shown to be safe dential , golf courses, and commercial and is more effective at lower rates than 2,4- when applied at seeding of annual bluegrass properties. The objective of this research was D and other auxin herbicides (Flessner et al., (Poa annua L.), tall fescue (Festuca arundi- to determine reseeding intervals for perennial 2011; Turner et al., 2009). Aminocyclopyra- nacea Schreb.), perennial ryegrass (Lolium ryegrass and tall fescue after aminocyclopya- chlor has efficacy on many broadleaf weed perenne L.), and fine fescue for pre-weed chlor applications. species including wild carrot (Daucus carota control during establishment (Anonymous, L.) Canada thistle [Cirsium arvense (L.) 1998; Enache and Ilnicki, 1991). Reicher Scop.], Japanese knotweed (Fallopia japon- et al. (1999) found that quinclorac at 0.84 Materials and Methods ica Houtt.), catsear dandelion (Hypochoeris kgÁha–1 did not injure kentucky bluegrass radicata L.), and plantains (Plantago spp.) (Poa pratensis L.) or perennial ryegrass when Experiments were conducted in Griffin, applied at seeding. These experiments did GA, Knoxville, TN, and Lubbock, TX, from note that quinclorac applied at seeding de- Aug. 2010 to Mar. 2011. Experiments at all layed the cover of kentucky bluegrass up to three locations were initiated on mature, 16 weeks (Reicher et al., 1999). Bispyribac irrigated tall fescue that was mowed weekly Received for publication 27 June 2011. Accepted sodium applied 1 week before seeding (WBS) with a rotary mower at a 6.4-cm height. for publication 1 Oct. 2011. 1Graduate Assistant. reduced creeping bentgrass (Agrostis stoloni- Clippings were returned. Soil in Georgia was 2Assistant Professor. fera L.) and kentucky bluegrass by 30% and a Cecil sandy loam (fine, kaolinitic, ther- 3Associate Professor. 42% compared with the non-treated control, mic Typic Kanhapludults) with 2.5% organic 4To whom reprint requests should be addressed; respectively. However, these grasses were matter and a pH of 5.8. Soil in Tennessee e-mail [email protected]. safely established when bispyribac sodium was a Sequatchie loam (fine-loamy, siliceous,

798 HORTSCIENCE VOL. 47(6) JUNE 2012 TURF MANAGEMENT semiactive, thermic humic Hapludult) with in opposite directions with a single nozzle fertilizer was applied at 48 kg N/ha 4weeks 2.1% organic matter and a pH of 6.2%. Soil in (Teejet 9504E flat fan spray nozzle; Spray- after seeding (WAS) at each location. Texas was a Brownfield sand clay loam soil ing Systems Co., Roswell, GA) CO2-pressured Measurements and statistical analysis. (loamy, mixed, superactive, thermic Arenic sprayer calibrated to deliver 375 LÁha–1.In Perennial ryegrass and tall fescue cover were Aridic Paleustalfs) with 1.6% organic matter Tennesse and Texas, treatments were ap- assessed visually, because Yelverton et al. and a pH of 8.0. plied by making one pass per plot with a four (2009) reported that visual ratings of herbi- Experimental design. Separate studies nozzle (Teejet 8002 flat fan spray nozzle; cide responses in turf were highly correlated were conducted to determine reseeding in- Spraying Systems Co.) CO2-pressured sprayer to those measured using the line intersect tervals for perennial ryegrass and tall fescue. calibrated to deliver 280 LÁha–1. method or digital image analysis. Turf cover The experimental design for each was a ran- Turfgrass seeding and maintenance. Seven was evaluated for each species 2, 4, 8, 12, and domized complete block with four replica- days before seeding, each experimental site 20 WAS on a percent scale where 0 equaled tions. Four herbicide treatments were applied received a broadcast application of no turf cover and 100 equaled complete turf at four application timings before seeding in (Roundup Pro. Monsanto Company, St. Louis, cover. addition to a non-treated control. Aminocyclo- MO) at 3.3 kg/a.i./ha to kill existing vegetation Data were subjected to analysis of variance pyrachlor (Imprelis 2SL; DuPont, Wilmington, and facilitate visual assessment of turfgrass with main effects and all possible interac- DE) was applied at 39, 78, or 158 g/a.i./ha and seedling cover. On the day of seeding, the field tions tested using the appropriate expected 2, 4-D + dicamba + MCPP (Trimec Classic was mowed to 3.8 cm with a rotary mower, mean square values as described by McIntosh 2.72 SL; PBI Gordon Corp., Kansas City, debris was removed, and the seedbed received (1983). Data were pooled from all three loca- MO) was applied at 1100 + 300 + 100 g/a.i./ two additional passes with a vertical mower tions because location-by-treatment interac- ha, respectively. Herbicide treatments were set to a depth of 1.3 cm. Perennial ryegrass tions were not detected for tall fescue or applied 0, 2, 4, or 6 WBS. Application dates (Manhattan IV perennial ryegrass; Pure Seed perennial ryegrass cover. Means were sepa- in Georgia, Tennessee, and Texas are pre- Testing, Inc., Hubbard, OR) and tall fescue rated with Fisher’s protected least significant sented in Table 1. Aminocyclopyrachlor rates (Titan tall fescue; Seed Research of Oregon, difference test at the 0.05 P level. were selected from previous research evalu- Inc., Corvallis, OR) were seeded separately ating broadcast applications of aminocyclo- and perpendicular to herbicide treatments over pyrachlor for selective broadleaf weed control half of all plots at 390 kgÁha–1 with a drop Results (Flessner et al., 2011). The 2, 4-D + dicamba + spreader. Herbicide treatments scheduled for MCPP rates were selected from label recom- the day of seeding were applied immediately Perennial ryegrass study. A treatment- mendations (Anonymous, 2004). after seeding each grass species. After seed- by-application timing interaction was not Treatments were applied to 1 · 3.6-m ing, tall fescue and perennial ryegrass were detected on any date for perennial ryegrass plots in Georgia and 1.5 · 3.6-m plots in irrigated daily to promote germination and cover. Perennial ryegrass cover after ami- Texas and Tennessee. In Georgia, treat- applied as needed to prevent turf wilt after nocyclopyrachlor and 2,4-D + dicamaba + ments were applied by making two passes germination. A 10N–10P O –10K O) granular MCPP treatments was similar and not re- 2 5 2 duced from the non-treated control on any date regardless of application timing (Table 2). At 4, 8, and 12 WAS, perennial ryegrass Table 1. Dates of treatment application and seeding in field experiments in Griffin, GA, Knoxville, TN, and had 88%, 95%, and 99% cover, respectively, Lubbock, TX, in 2010. for all herbicides applied 0, 2, 4, or 6 WBS. Application Week before seeding Georgia Tennessee Texas At 20 WAS, no significant differences in Treatments 6 17 Aug. 16 Aug. 24 Aug. perennial ryegrass cover were detected among 4 1 Sept. 30 Aug. 7 Sept. application timing or herbicide treatments. 2 14 Sept. 13 Sept. 21 Sept. Tall fescue study. A treatment-by-application 0 29 Sept. 28 Sept. 5 Oct. timing interaction was not detected on any date Glyphosate 1 21 Sept. 20 Sept. 28 Sept. Seeding 29 Sept. 28 Sept. 5 Oct. for tall fescue cover. Tall fescue cover after aminocyclopyrachlor and 2,4-D + dicamba + MCPP treatments was similar and was not reduced from the non-treated control on any Table 2. ‘Manhattan IV’ perennial ryegrass cover after herbicide treatments at four application timings date regardless of application timing (Table 3). z before seeding in field experiments conducted in 2010–2011. At 4, 8, and 12 WAS, tall fescue had 77%, Perennial ryegrass cover (WAS)y 94%, and 96% cover, respectively, for all her- 2 4 8 12 20 bicides applied at any of the timings. At 20 Treatmentx Rate (g/a.i./ha) ------% ------WAS, no significant differences in tall fes- Aminocyclopyrachlor 39 54 88 96 99 99 cue cover were detected among application 79 54 88 95 98 99 timings or herbicide treatments. 158 54 88 95 99 99 2,4-D + dicamba + MCPP 1100 + 100 + 300 54 89 96 99 99 w LSD0.05 ------NS ------Discussion

Application timing (WBS)v ------% ------Herbicide options are limited for turfgrass 0 5488959999managers who are looking to control prob- 2 5488959999lematic weeds during establishment of cool- 4 5488959999season grasses. Herbicides commonly used in 6 54889599100established cool-season turfgrasses for PRE LSD0.05 ------NS ------weed control such as , oryzalin, Non-treated control 54 88 96 99 98 oxadiazon, , and prodiamine zMeans are combined for experiments conducted in, Griffin, GA, Knoxville, TN, and Lubbock, TX. y can injure immature and newly seeded cool- WAS = weeks after seeding. season turfgrass potentially leading to total xInitial applications were applied on 17 Aug., 16 Aug., and 24 Aug. in Georgia, Tennessee, and Texas, respectively. Seeding dates were 29 Sept., 28 Sept., and 5 Oct. in Georgia, Tennessee, and Texas, failure of turfgrass establishment (Fermanian respectively. and Haley, 1994; Johnson and Murphy, 1991; wNS = nonsignificant at 0.05 P level. Landschoot et al., 1993). Herbicides com- vWBS = weeks before seeding. monly used for post-weed control including MCPP = methylchlorophenoxypropionic acid; LSD = least significant difference. 2,4-D, dicamba, MCPP, MSMA, or triclopyr

HORTSCIENCE VOL. 47(6) JUNE 2012 799 Table 3. ‘Titan II’ tall fescue cover after herbicide treatments at four application timings before seeding in to spring-applied herbicides. Weed Technol. field experiments conducted in 2010–2011.z 5:304–309. Tall fescue cover (WAS)y Landschoot, P.J., T.L. Watschke, and B.F. Hoyland. 1993. Influence of preemergence and postemer- 2481220gence herbicides on rooting of turfgrasses. Treatmentx Rate (g/a.i./ha) ------%------Weed Technol. 7:123–126. Aminocyclopyrachlor 39 36 77 94 96 98 Lycan, D.W. and S.E. Hart. 2006. Cool-season 79 36 77 94 96 99 turfgrass reseeding intervals for bispyribac- 158 36 76 94 97 99 sodium. Weed Technol. 20:526–529. 2,4-D + dicamba + MCPP 1100 + 100 + 300 36 77 95 96 99 McCalla, J.H., Jr., M.D. Richardson, D.E. Karcher, w LSD0.05 ------NS ------and J.W. Boyd. 2004. Tolerance of seedling bermudagrass to postemergence herbicides. Application timing (WBS)v ------%------Crop Sci. 44:1330–1336. 0 3677949799McCullough, P.E., J.T. Brosnan, and G.K. Breeden. 2 3676949799 2011. Tall fescue and perennial ryegrass reseed- 4 3677949699 ing intervals for amicarbazone. HortScience 46: 6 3677949699 648–650. LSD0.05 ------NS------McCullough, P.E. and W. Nutt. 2010. Bermudagrass Non-treated control 37 77 94 96 99 reseeding intervals for rimsulfuron, simazine, zMeans are combined for experiments conducted in Griffin, GA, Knoxville, TN, and Lubbock, TX. and sulfosulfuron. HortScience 45:693–695. yWAS = weeks after seeding. McElroy,J.S.,G.K.Breeden,F.H.Yelverton,T.W. xInitial applications were applied on 17 Aug., 16 Aug., and 24 Aug. in Georgia, Tennessee, and Texas, Gannon, S.D. Askew, and J.F. Derr. 2005. Re- respectively. Seeding dates were 29 Sept., 28 Sept., and 5 Oct. in Georgia, Tennessee, and Texas, sponse of four improved seeded bermudagrass respectively. cultivars to postemergence herbicides during wNS = nonsignificant at 0.05 P level. seeded establishment. Weed Technol. 19:979–985. vWBS = weeks before seeding. McIntosh, M.S. 1983. Analysis of combined ex- MCPP = methylchlorophenoxypropionic acid; LSD = least significant difference. periments. Agron. J. 75:153–155. Reicher, Z.J., D.V. Weisenberger, and C.S. Throssell. 1999. Turf safety and Effectiveness of dithiopyr and quinclorac for large crabgrass (Digitaria sanguinalis) control in spring-seeded turf. are recommended for use after seedlings have Anonymous. 2004. Trimec Classic 2.72 SL herbi- Weed Technol. 13:253–256. begun tillering or after mowing three to four cide label. PBI Gordon Corp., Kansas City, Rudenko, M. 2009. Integrating restoration and times (Askew and Hipkins, 2005). MO. ecologically based weed management practices Results from this study demonstrate that Anonymous. 2010. Imprelis herbicide label. DuPont, for invasive knotweed control. MS thesis, perennial ryegrass and tall fescue can be Newark, DE. Oregon State University. p. 24–30. Askew, S.D., J.B. Beam, and W.L. Barker. 2004. Sterling, T. and J. Hall. 1997. Mechanism of action safely treated with aminocyclopyrachlor ap- Chemical options for selective control or sup- –1 of natural auxins and the auxinic herbicides, plied at 39, 79, and 158 gÁha immediately pression of bermudagrass in creeping bentgrass, p. 111–141. In: Roe, M., J. Burton, and R. Kuhr after seeding. Perennial ryegrass and tall fes- kentucky bluegrass, and perennial ryegrass. (eds.). Herbicide activity: Toxicology, bio- cue establishment appears uninhibited from Weed Sci. Soc. 57:101. chemistry, and molecular biology. IOS Press, aminocyclopyrachlor application; thus, no Askew, S.D. and P.L. Hipkins. 2005. Pest manage- The Netherlands. reseeding interval is required. Practitioners ment guide for home grounds and animals- Struckmeyer, B. 1951. Comparative effects of could selectively control broadleaf popula- weeds section. Virginia Cooperative Exten- growth substances on stem anatomy, p. 167– tions with aminocyclopyrachlor in the fall sion, Blacksburg, VA. p. 144–153. 174. Plant growth substances. Univ. Wisconsin and safely reseed perennial ryegrass or tall Bukum, B., R.B. Bradley, S.J. Nissen, P. Westra, Press, Madison, WI. D.L. Shaner, and G. Brunk. 2010. Absorption Turner, R., J. Claus, E. Hidalgo, M. Holliday, and fescue immediately after application. These and translocation of aminocyclopyrachlor and G. Armel. 2009. Technical introduction of the results are comparable to similar studies that aminocyclopyrachlor-Methyl ester in Canada new DuPont vegetation management herbicide have shown certain herbicides including iso- thistle (Cirsium arvense). Weed Sci. 58:96–102. aminocyclopyrachlor. Proc. South. Weed Sci. xaflutole, , and quinclorac to be Curtis, D.W., B.J. Hinds-Cook, J. Barbara, B.D. Soc. 62:405. safe when applied during establishment of Brewster, D. Bill, A.G. Hulting, and C.A. Watson, D. 1950. Anatomical modification of cool-season turfgrass (Askew et al., 2004; Mallory-Smith. 2009. Tolerance of perennial velvet bent grass (Agrostis canina L.) caused by Willis et al., 2006). Further research should ryegrass and tall fescue grown for seed to soil treatment with 2,4-dichlorophenoxyacetic investigate application rates and intervals for aminocyclopyrachlor (DPXKJM-44). Western acid. Amer. J. Bot. 37:424–431. use of aminocyclopyrachlor after turfgrass Weed Sci. Soc. 62:70–71. Willis, J.B., J.B. Beam, W.L. Barker, and S.D. Enache, A.E. and R.D. Ilnicki. 1991. Bas 514 and Askew. 2006. Weed control options in spring- seedling emergence in perennial ryegrass and dithiopyr for weed control in cool-season turf- seeded tall fescue (Festuca arundinacea). Weed tall fescue stands as well as reseeding in- grasses. Weed Technol. 5:616–621. Technology 20:1040–1046. tervals with aminocyclopyrachlor application Fermanian, T.W. and J.E. Haley. 1994. Application Willis, J.B., D.B. Ricker, and S.D. Askew. 2007. on warm-season turfgrass seed and vegeta- of prodiamine to immature turfs. Weed Tech- Sulfonylurea herbicides applied during early tive material. nol. 8:617–620. establishment of seeded bermudagrass. Weed Flessner, M.L., R.R. Dute, and J.S. McElroy. 2011. Technol. 21:1035–1038. Literature Cited Anatomical response of St. Augustinegrass to Yelverton, F.H., J.A. Hoyle, T.W. Gannon, and aminocyclopyrachlor treatment. Weed Sci. 59: L.S. Warren. 2009. Plant counts, digital image Anonymous. 1998. Drive 75 DF herbicide label. 263–269. analysis, and visual ratings for estimating weed EPA Reg. No. 7969-130. BASF Corporation, Johnson, B.J. and T.R. Murphy. 1991. Response to control in turf: Are they correlated? Proc. South Research Triangle Park, NC. fall-seeded tall fescue (Festuca Arundinacea) Weed Sci. Soc. 62:399.

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