Turfgrass and Environmental Research Online

1 Using Science to Benefit Golf Turfgrass and EnvironmentalResearch OnlineVolume 8, Number 21 November 1, 2009 Research at the university of Tennessee has been investigating postemergence herbicide applicationsfor selective bermudagrass control in several varieties of zoysiagrass turf. Results indicate 'Tifway'bermudagrass control increases when fluazifop (Trade name: Fusilade II) is tank-mixed with triclopyr(Trade name:Turflon Ester) on 4-week application intervals, and triclopyr safens the application of flu-azifop on 'Compadre', 'Meyer', 'Palisades', and 'Zeon' zoysiagrass. Shown above is Diamond zoysia-grass injury at New Life Turf in Norway, purpose of USGA Turfgrass and Environmental Research Onlineis to effectively communicate the results ofresearch projects funded under USGA s Turfgrass and Environmental Research Program to all who can benefitfrom such knowledge.

2 Since 1983, the USGA has funded more than 400 projects at a cost of $34 million. The pri-vate, non-profit Research program provides funding opportunities to university faculty interested in working on envi-ronmental and turf management problems affecting golf courses. The outstanding playing conditions of today sgolf courses are a direct result of using science to benefit golf. EditorJeff Nus, Rogers PlaceLawrence, KS 832-2300(785) 832-9265 (fax) Research DirectorMichael P. Kenna, Box 2227 Stillwater, OK 743-3900(405) 743-3910 (fax)Permission to reproduce articles or material in theUSGA Turfgrass and Environmental Research Online (ISSN 1541-0277) isgranted to newspapers, periodicals, and educational institutions (unless specifically noted otherwise). Credit must be given tothe author(s), the article title, and USGA Turfgrass and Environmental Research Onlineincluding issue and number.

3 Copyrightprotection must be afforded. To reprint material in other media, written permission must be obtained from the USGA. In anycase, neither articles nor other material may be copied or used for any advertising, promotion, or commercial purposes. USGA Turfgrass and Environmental Research CommitteeSteve Smyers, Co-chairmanGene McClure,Co-chairmanJulie Dionne, DodsonKimberly Erusha, Grass, CGCSAli Harivandi, P. Kenna, Krans, MooreJeff Nus, Rieke, T. SnowClark Throssell, Tisserat, Warnke, Watson, Williamson, (Zoysia spp.) and bermuda-grass (Cynodon dactylon(L.) Pers.) are both usedas highly maintained turf on golf course settingsthroughout the transition zone and southernUnited States. However, bermudagrass canbecome a weed once it contaminates an area ofzoysiagrass turf. When grown under the identicaledaphic and Environmental conditions, bermuda-grass will commonly outcompete zoysiagrass.

4 Zoysiagrass can easily be invaded bybermudagrass as many zoysiagrass fairways andtee boxes are surrounded by common or hybridbermudagrass rough. This situation providesbermudagrass with an easy opportunity toencroach into the fairways from the rough andinvade weak or thin zoysiagrass areas. Onceinfested, bermudagrass will disrupt zoysiagrassuniformity, most easily seen by variations inmorning dew pattern and by entering dormanyearlier than zoysiagrass (12). There are few effective measures forbermudagrass control in zoysiagrass removing the contaminated area andreplacing with sod is only applicable if the infect-ed area is relatively small. Chemically removingbermudagrass takes multiple applications ofglyphosate. However, non-selective options areimpractical because they result in the death of theweed and desired turf.

5 These large dead areas canactually promote bermudagrass regrowth whichSelective Control Options for BermudagrassContamination in Zoysiagrass TurfDustin F. Lewis, J. Scott McElroy, John C. Sorochan, and Greg K. BreedenSUMMARYR esearch at the university of Tennessee has been invest-ing postemergence herbicide applications for selectivebermudagrass control in several varieties of zoysiagrassturf. Overall results from this study indicate:'Tifway' bermudagrass control increases when fluazifop(Trade name: Fusilade II) is tank-mixed with triclopyr(Trade name: Turflon Ester) on 4-week application safens the application of fluazifop on'Compadre', 'Meyer', 'Palisades', and 'Zeon' fluazifop tank-mixed with triclopyr increasesinjury and cover reduction to 'Diamond' zoysiagrass com-pared to fluazifop applied application intervals increase zoysiagrassinjury and cover reduction compared to four-week applica-tion F.

6 LEWIS, Graduate Student; Dept. of Plant Sciences, university of Tennessee, Knoxville, TN; J. SCOTT MCELROY, , Assistant Professor, Turfgrass Weed Science; Agronomyand Soils Dept., Auburn university , Auburn, AL; JOHN , , Associate Professor, Turfgrass Science; andGREG K. BREEDEN, Research Technician; Dept. of PlantSciences, university of Tennessee, Knoxville, TN1 Bermudagrass encroachment from the rough/ intermediaterough into a 'Meyer' zoysiagrass fairway. Notice the dewpattern on the bermudagrass is much more prevalent thanon the Turfgrass and Environmental Research Online8(21) Record Number: 157503will reinvade from its extensive rhizomatous net-work (2). Selective herbicides often fail sinceboth bermudagrass and zoysiagrass are C4turf-grasses that react similar to herbicide treatments. Due to the needs of zoysiagrass managers,the university of Tennessee, Auburn university ,and the USGA partnered with Turfgrass managersacross the Southeast to evaluate selective poste-mergence herbicide treatments for bermudagrasscontrol in various zoysiagrasses.

7 Many productsregistered for selective bermudagrass controlbelong to the aryloxyphenoxy-propionate (AOPP)herbicide family. Research has shown that thesematerials can cause injury to zoysiagrass (3, 4, 7,6, 10). Other Research has indicated that theAOPP herbicide fluazifop tank-mixed with thesynthetic auxin herbicide triclopyr could be safely2 Table 1. Experimental locations, plant materials, and initiation dates for Research City/StatePlant MaterialSpecies Initiation DateAtlanta Athletic ClubDuluth, GADiamond zoysiagrass Z. matrellaJune 2008 Zeon zoysiagrassZ. matrellaJune 2008 East Tennessee ERC Knoxville, TN Tifway bermudagrass Cynodon hybrid May 2007-08 Compadre zoysiagrass Z. japonicaMay 2007-08 Honors CourseOoltewah, TN Meyer zoysiagrass Z. japonicaJune 2008 Little CourseFranklin, TN Palisades zoysiagrass Z.

8 JaponicaMay 2008 New Life TurfNorway, SC Diamond zoysiagrass Z. matrellaJune 2008 Palisades zoysiagrass Z. japonicaJune 2008 Patches of dormant bermudagrass in a 'still-green' 'Meyer' zoysiagrass fairway. Photo credit to David Stone, Superintendentof the Honors Course in Ooltewah, to 'Cavalier' and 'Meyer' zoysiagrass (1,10). Turfgrasses are known to have differences inherbicide tolerance among cultivars (5, 8); there-fore, we tested these products independently andcombined across several zoysiagrass objective of this study was to deter-mine the optimal timing and rate of fluazifop(Trade Name: Fusilade II) with or without tri-clopyr (Trade Name: Turflon Ester) for bermuda-grass control in zoysiagrass and MethodsResearch was conducted to evaluate'Tifway' bermudagrass [C. dactylon(L.) Pers. XC. transvaalensisBurtt-Davy] control and to various timings and rates of flu-azifop applied alone or tank-mixed with all locations (Table 1), experimental units weremanaged and maintained as a golf course were arranged in a randomized complete3 Figure 1.

9 Tifway bermudagrass injury taken 2 weeks after final 2. Zoysia consortium tolerance affected by fluazifop rate by triclopyr rate interaction taken two weeks after final design with four replications. Herbicideapplications were made with a CO2pressurizedpesticide applicator equipped with four 11002 XRflat fan TeeJet nozzles calibrated to deliver 30 gal-lons per acre. All treatments included a non-ionicsurfactant ( , v/v). In order to determine season-long controland tolerance, trials were rated both visual anddigitally. Visual assessments were taken twoweeks after the initial application (2 WAIA) andcontinued until two weeks after the final applica-tion (2 WAFA). Control and tolerance were ratedon a 0-100% scale (0%= no visible injury; 100%= complete plant death) with greater than or equalto 90% injury considered acceptable bermuda-grass control and less than or equal to 20% injuryconsidered acceptable zoysiagrass image analysis (DIA) was taken to deter-mine percent zoysiagrass cover using Sigma ScanPro software (9).

10 Analysis of variance (P= ) was con-ducted using MIXED model methodology in SAS(12) and analyzed as a randomized completeblock design with 4x2x2 factorial (four fluazifoprates by two triclopyr rates x two application tim-4 Figure 3. Zoysia consortium tolerance affected by fluazifop rate by application timing interaction taken two weeks after 4. Zoysia consortium cover affected by fluazifop rate by triclopyr rate interaction taken 2 weeks after final ) arrangement of treatments. During statisti-cal analysis, it was determined that 'Diamond'zoysiagrass responded differently than the otherfour tested zoysiagrasses, which corresponded toobservations made in the field. Therefore, thedata was arranged into three distinct groups:'Tifway' bermudagrass; Zoysia consortium (com-bined analysis of 'Compadre', 'Meyer', 'Palisades',and 'Zeon' zoysiagrass); and 'Diamond' zoysia-grass.