Fine fescue is a group of several species in the genus Fesctuca, including chewings fescue, hard fescue, strong creeping red fescue, and slender creeping red fescue (F. rubra ssp. littoralis) (Bonos et al., 2006). They are known for drought and shade tolerance, as well as minimal requirements for maintenance and fertility. In recent years, the increasing demand for low-input turfgrass makes fine fescue species desirable for various turf uses (Watkins et al., 2012).
The presence of annual bluegrass may reduce turf quality as a result of to its poor disease, heat, drought, and wear tolerances (Beard et al., 1978). Annual bluegrass is a prolific seed producer that germinates across a wide range of temperature, from 7 to 29 °C (McElroy et al., 2004). Annual bluegrass control in turfgrass requires integrated strategies of cultural and chemical control practices. Deep and infrequent irrigation encourages root development of desirable turfgrasses while reducing soil moisture for annual bluegrass infestations (Gaussoin and Branham, 1989). Turf managers may also collect clippings to minimize the return of annual bluegrass seeds to the soil, and balance fertility to enhance turfgrass competition with populations (Youngner, 1959). Preemergence herbicides are used to control annual bluegrass in turfgrass management, but applications often do not provide satisfying results because of poor efficacy of the available chemistries, herbicide resistance, or the presence of perennial biotypes (Callahan and McDonald, 1992; Isgrigg et al., 2002; Juska and Hanson, 1967; Yu and McCullough, 2014). Postemergence herbicides for annual bluegrass control in cool-season grasses, especially fine fescues, are limited. For example, amicarbazone and bispyribac-sodium can be used for annual bluegrass control in chewings fescue, creeping bentgrass (Agrostis stolonifera), perennial ryegrass (Lolium perenne), and tall fescue (Schedonorus arundinacea); however, there is concern over injury to other cultivated cool-season turfgrass species (Arysta LifeScience, 2012; Lycan and Hart, 2005; McCullough et al., 2010).
Methiozolin is a new herbicide in the isoxazoline chemical family. Koo et al. (2014) reported that it controlled annual bluegrass selectively in various cool- and warm-season turfgrasses. It has been evaluated extensively on creeping bentgrass, perennial ryegrass, and kentucky bluegrass (Poa pratensis) (Hoisington et al., 2014; McCullough and de Barreda, 2012). Methiozolin controls annual bluegrass postemergence when applied at 0.5 to 1 kg·ha–1 two to five times per year (Flessner et al., 2013; Koo et al., 2014; Xiong et al., 2015). Despite various research, little has been published to date on the phytotoxicity of methiozolin on fine fescue species. Therefore, this experiment was conducted to investigate the safety of methiozolin application regimens on hard fescue, chewings fescue, and strong creeping red fescue—the three most widely used fine fescue species.
Arysta LifeScience 2012 Xonerate herbicide label. Arysta LifeScience, Cary, NC
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