Field experiments were conducted in Auburn, AL in 2008 and 2009 to assess new aryloxyphenoxypropionate (AOPP) herbicides applied alone and tank-mixed with triclopyr for Tifway bermudagrass control in Zorro zoysiagrass. Treatments included three sequential applications of clodinafop (0.07 kg ai ha−1); triclopyr (1.12 kg ae ha−1); clodinafop + triclopyr (0.07 + 1.12 kg ha−1); fenoxaprop (0.10 kg ai ha−1); fenoxaprop + triclopyr (0.10 + 1.12 kg ha−1); metamifop (0.40 kg ai ha−1); and metamifop + triclopyr (0.40 + 1.12 kg ha−1). Clodinafop, fenoxaprop, and metamifop applied alone controlled Tifway bermudagrass 32 to 65% when rated 3 wk after the final application; however, the addition of triclopyr to these AOPP herbicides increased bermudagrass control to ≥ 89%. All AOPP herbicides applied alone caused unacceptable injury to Zorro zoysiagrass (20 to 42%) 3 wk after the final application. Clodinafop resulted in the greatest zoysiagrass injury (42%), whereas metamifop caused moderate injury (20%). Zorro zoysiagrass exhibited less injury (< 3%) and greater turf coverage (≥ 95%) when AOPP herbicides were tank-mixed with triclopyr. Of the three AOPP herbicides evaluated in this study, only fenoxaprop is currently labeled for use on turfgrass. However, the nonlabeled herbicides (clodinafop and metamifop) provided bermudagrass control and zoysiagrass safety equal to the commercial standard (fenoxaprop) 3 wk after the final application when tank-mixed with triclopyr. Where zoysiagrass is contaminated with bermudagrass, turf managers will likely have to make applications of AOPP herbicides tank-mixed with triclopyr over multiple years to control bermudagrass as it will continue to regrow from deep rhizomes.

Indaziflam is a new herbicide which potentially provides pre‐ and postemergence control of broadleaf and grass weeds. Two studies were conducted to evaluate indaziflam control of several weed species utilizing different application regimes. Single applications included indaziflam applied at 40 or 60 g ai/ha in October or November, and 20, 40, or 60 g ai/ha in March. Sequential applications included indaziflam applied at 40 followed by (fb) 40 g ai/ha in October and March, 60 fb 20 g ai/ha in October and March, 40 fb 40 g ai/ha in November and March, and 60 fb 20 g ai/ha in November and March. Prodiamine and oxadiazon were also applied as standard comparisons. Indaziflam applied at 60 g ai/ha in November provided the most consistent control across weed species. This treatment controlled annual bluegrass > 90% 20 weeks after treatment (WAT) and large crabgrass > 90% 29 WAT. All sequential indaziflam applications (except for the 40 fb 40 g ai/ha in November and March) controlled annual bluegrass > 90%. All rates and timings of indaziflam controlled lawn burweed at least 40% greater than industry standards. Indaziflam applied at 40 g ai/ha in October and March controlled cock's‐comb kyllinga 80%. Indaziflam provided better weed control and longer residual activity than industry standards in some cases, however, weed control varied among species.

Zoysiagrass (Zoysia spp.) is a popular turfgrass species for use on lawns, sod farms, and golf courses in the transitional and southern climatic zones of the United States. One common problem in managing zoysiagrass is the contamination and subsequent removal of bermudagrass (Cynodon spp.). Various herbicides and herbicide tank‐mixes may be utilized for bermudagrass control in zoysiagrass. Research was conducted in Fayetteville, AR, and Auburn, AL, to evaluate aminocyclopyrachlor, fluazifop, fenoxaprop, triclopyr, and their combinations for bermudagrass suppression in zoysiagrass. Fluazifop at 0.105 kg active ingredient (a.i.) ha–1 suppressed bermudagrass most, but this application caused unacceptable injury and quality reduction to zoysiagrass. Tank‐mixing fluazifop or fenoxaprop at 0.14 kg ai ha–1 with triclopyr at 0.56 kg acid equivalent (a.e.) ha–1 reduced zoysiagrass injury and improved turf quality over fluazifop or fenoxaprop alone. Fluazifop + triclopyr provided more bermudagrass suppression than fenoxaprop + triclopyr. Aminocyclopyrachlor (0.026 or 0.071 kg a.e. ha–1) did not reduce herbicide injury from fluazifop or fenoxaprop applications to zoysiagrass and did not provide significant bermudagrass suppression. Results suggest that fluazifop + triclopyr and fenoxaprop + triclopyr remain the best treatments for bermudagrass suppression in zoysiagrass because they provide bermudagrass suppression without reducing zoysiagrass quality.

Field experiments were conducted to evaluate the efficacy of herbicides and soil sterilants for the fairway conversion of ‘Tifway’ bermudagrass to ‘Zorro’ zoysiagrass. Treatments included glyphosate (4.48 kg ae ha−1), EPTC (7.84 kg ai ha−1), dazomet (338 kg ai ha−1), siduron (13.4 kg ai ha−1), glyphosate plus ETPC (4.48 + 7.84 kg ha−1), glyphosate plus dazomet (4.48 + 338 kg ha−1), EPTC plus siduron (7.84 + 13.4 kg ha−1), and dazomet plus siduron (338 + 13.4 kg ha−1). Glyphosate treatments were applied 5 wk prior to establishment (WPE), dazomet and EPTC treatments were applied 3 WPE, and siduron was applied at establishment. Dazomet and EPTC treatments were incorporated to a depth of 10 to 15 cm with a rotary tiller and rolled with a weighted roller to reduce losses from volatilization after application. Zorro zoysiagrass was established in June 2008 and 2009 using a mixture of rhizomes and stolons at a rate of 76 cm3m−2. Results indicate that glyphosate + dazomet, glyphosate + EPTC, dazomet + siduron, and EPTC + siduron were equally effective at controlling Tifway bermudagrass. EPTC and dazomet controlled bermudagrass more effectively when used in combination with glyphosate or siduron. There were no significant differences in bermudagrass cover between the EPTC combinations with glyphosate or siduron and dazomet applied with glyphosate or siduron. Comparing EPTC- and dazomet-alone, EPTC yielded less bermudagrass cover (32%) than dazomet (71%). At present, research is limited on using EPTC for controlling perennial grasses in turfgrass systems. Data from these studies demonstrate the potential use of EPTC as a preplant soil herbicide to control hybrid bermudagrass during zoysiagrass renovation.

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