Fescue is one of the largest genera of the grass tribe Poaceae (Clayton and Renvoize, 1986). Of the ≈100 fescue species used in the United States and Europe, six cool-season fine-leaf fescue species are commonly used as turfgrasses in temperate and subarctic climates (Turgeon, 1999). Extensively used for forage, turf, or conservation purposes, fescue species vary greatly in morphology, cytology, and growth habits. Fine-leaf fescue is a common turfgrass in northeastern U.S. lawns and turf, especially in shaded areas (Jauhar, 1993). The fine-leaf fescue group includes slender creeping fescue (Festuca rubra ssp. trichophylla or ssp. littoralis) and strong creeping fescues (F. rubra ssp. rubra), chewing's fescue (F. rubra ssp. commutata), hard fescue (Festuca longifolia), and sheep fescue (Festuca ovina).
Fine-leaf fescue breeders have recently developed genetically improved cultivars that possess tolerance to acidic and low-fertility soils, as well as moderate shade and full-sun conditions. Currently, there is increased interest by the United States and European turfgrass industry in the use of fine-leaf fescue for lawn and golf turf as well as low-maintenance turf settings. Fine-leaf fescue is especially useful for settings experiencing variable light conditions and poor soils, and in regions with temperate climates. In addition, fescue generally thrives in dry, infertile sites such as roadside settings (Ruemmele et al., 1995).
The presence of turfgrass in a landscape impacts the human lifestyle from a visual, functional, and recreational point of view. In the United States, there are currently greater than 12 million hectares of turfgrass, including lawns, parks, golf courses, sod farms, industrial and institutional grounds, and highway right-of ways. In New York State alone, over 3.4 million hectares have been established in turfgrass (Ropel et al., 2004). In all turf settings, especially lawn and roadside turf, weeds are a key pest problem. A substantial pesticide market (over $2 billion) currently exists for the control of weeds, insects, and diseases in private and commercial turfgrass settings in the United States. Although herbicides continue to be the predominant form of weed management in commercial turf settings, herbicide use in public and private landscapes is increasingly challenged by environmental and health concerns (Mortensen et al., 2000). Consequently, turfgrass stakeholders, including homeowners and turf managers, are seeking alternative weed management tools (Matteson, 1995). One preventive strategy to minimize weed infestation is the use of appropriate turf mixtures or cultivars that are well-adapted to a given setting. Weeds are much less likely to invade a well-managed turf in optimal condition, maintained with appropriate cultural practices including timely mowing, fertilization, and irrigation (Bertin and Weston, 2004).
Biological and organic approaches for weed management in turf have often not provided effective long-term control of turf weeds (Bertin and Weston, 2004). Although plant pathogenic organisms have been evaluated for selective control of turf weeds, few, if any, commercial biocontrol products for weed management are currently available. Evaluation of organic products for weed management in turf has shown that most products do not provide selective or cost-effective, long-term weed suppression. Weed removal by mulching, cultivation, flame-burning, and steaming can be used in landscapes, but is cost prohibitive and sometimes injurious to turf (Bertin and Weston, 2004; Weston, 1999). Organic products such as acetic acid or clove oil-based products will result in significant turf injury. Corn gluten meal can provide some initial pre-emergent weed suppression, but many studies, including our own, have shown inconsistent control (Bertin and Weston, 2004).
Over the last decade, the study of plant-plant interactions and the use of allelopathy and plant interference as a potential weed management tool has received increasing attention in the literature (Hoffman et al., 1996; Weston and Duke, 2003; Wu et al., 1999). The use of allelopathy for weed management relies upon the species-specific responses of a target weed to chronic, and/or sublethal doses of an allelochemical, which can be exuded or leached from nearby living plants or decomposing residues. Weed suppressive cover crops that have been successfully used to suppress annual weeds have included economically important cereals such as wheat (Triticum aestivum), oat (Avena sativa), rye (Secale cereale), barley (Hordeum vulgare), sorghum (Sorghum bicolor), and rice (Oryza sativa) (Putnam and Tang, 1986). Although recent studies on allelopathic crops have focused on these key species, many other weedy and crop species show the promise of allelopathic potential for the suppression of surrounding vegetation. However, few studies have been conducted to further evaluate the allelopathic potential of these additional species (Hoffman et al., 1996; Weston and Duke, 2003). Recent trials with weed suppressive ornamental groundcovers have shown that the ability to establish rapidly, produce large quantities of biomass, and reduce light availability at the soil surface by producing a dense canopy and allelopathic properties can all influence weed suppressive ability (Eom et al., 2005).
Previous field experiments have shown that fescue species can be strongly weed suppressive when used for erosion control in agronomic, orchard, and vineyard settings (Malik et al., 2000; McGourty and Christensen, 1998; Morgan and Boubaki, 1999). Most studies have focused on the weed suppressive effects of tall fescue (Festuca arundinacea), which was shown to be potentially allelopathic (Peters and Zam, 1981). Weston (1990) has also demonstrated that strong creeping fescue was highly weed suppressive when established as living mulch or as killed sod in no-tillage field experiments. Although information on the potential allelopathic effects of fescue species is limited and generally unavailable for fine-leaf fescue turf cultivars, it is likely that one could easily select for enhanced weed suppressivity, given the great diversity of fescue germplasm available (Weston, 1996, 2005; Weston and Duke, 2003).
The objectives of this study, therefore, were to evaluate turfgrass quality and weed suppressive ability of fine-leaf fescue cultivars over a 3-year period. Based on initial evaluations, a subset of fine-leaf fescue cultivars was further evaluated in additional field trials conducted over a 2-year period.
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