Utilization of Stress Tolerant, Weed Suppressive Groundcovers for Low Maintenance Landscape Settings

Abstract

The recent emphasis on development of alternative, non-chemical weed strategies for landscape and roadside management has led to the study and utilization of well-adapted landscape groundcovers, including turfgrass and herbaceous ornamentals that can successfully withstand and suppress weed invasion. By selecting groundcovers which exhibit growth characteristics that result in consistent interference with weed establishment, one can successfully achieve effective long-term weed control in the landscape using reduced herbicide and labor inputs. In addition to allelopathic characteristics resulting in enhanced weed suppression due to the production and release of phytoinhibitors in the landscape, some groundcovers effectively suppress weedy invaders through competition for space, sunlight, moisture, nutrients and even direct alteration of the rhizosphere environment. Additional information related to weed biology and the impact of cultural practices used in the landscape on weed infestation are also critical when considering long-term and sustainable weed suppression for landscape and natural settings. Until recently, little information was available regarding the development of low maintenance landscapes for use in the Northeastern United States, with the exception of roadside trials documenting utilization of certain direct-seeded groundcovers in highway medians. Recent studies in both landscape and roadside settings have indicated that the selection and utilization of certain herbaceous perennial groundcovers and turfgrasses may not only result in lower labor inputs with respect to maintenance, they may further prevent the spread of noxious invasive weeds by severely limiting their ability to establish. When surveyed, stakeholders reported that weed suppressive groundcovers had much greater aesthetic appeal than those that were partially infested. Many of these groundcovers suppress weeds effectively by intense competition for resources, particularly by reduction in the amount of available light at the soil surface due to dense canopy cover. In addition, some groundcovers such as Nepeta x faasennii and Festuca rubra inhibit weed seedlings by their potential release of allelochemicals into the rhizosphere. Although still relatively novel, allelopathic groundcovers and turfgrasses offer interesting possibilities for future development of allelochemicals as bioherbicides and attractive, stress-tolerant and pest-resistant landscape plantings.