Managing cool‐season turfgrass without herbicides: Optimizing maintenance practices to control weeds

Abstract

Bans on the use of synthetic herbicides require innovative management approaches to maintain the attractiveness and usability of turfgrass swards. Such measures should include the use of locally adapted cultivars that germinate and establish quickly, resulting in the densest possible stands. Additionally, a number of turfgrasses have been reported to produce allelopathic substances that inhibit common turfgrass weeds. Mowing heights should be set to achieve maximum weed suppression while still providing acceptable quality for desired use. Sustainable turfgrass management programs have led to a reduction in fertilizer inputs; however, without the availability of herbicides, fertilization regimes need to be re‐examined. The literature suggests that broadleaf weeds are reduced but never fully controlled when more N is applied; therefore, finding a balance between what is needed and what is environmentally safe and sustainable is critical. Organic herbicides include plant pathogens from the fungus Phoma and strains of the bacterium Pseudomonas fluorescens. Both can be used to control several weeds common to turfgrasses. Acetic acid has also been shown to have herbicidal activity; however, it has limited residual activity, and its efficacy remains questionable on mature weeds. Thermal weed control can be used to sterilize a seedbank or spot treat existing weeds. Future turfgrass breeding programs could focus on understanding and enhancing the allelopathic potential of turfgrasses to outcompete weeds more effectively. Furthermore, more research should be directed at assessing the competitiveness of certain turfgrasses against weeds within the limitations of producing turfgrass areas of acceptable aesthetics and playing quality.

Viability of five fairway turfgrasses with and without chemical inputs

“…Fertilized KBG always had acceptable quality, but nonfertilized KBG would have required at least one herbicide application in the second year to sustain acceptable quality. Optimized, or at least minimal, fertilization is necessary to benefit the desired turfgrass species over weed encroachment (Hahn et al, 2020). Additionally, DeBels et al ( 2012) examined several turf species in Wisconsin, including two KBG cultivars, at three mowing heights and three N rates, and found that weed invasion decreased as both mowing height and N rate increased, the opposite conditions of a low-input fairway.…”

Repetitive Overseeding for Ecological Management of Grass Playing Fields

“…Weed management in turf is tightly linked to creating the best environment for desirable turf species to grow; therefore, sound overall turf management protocols with proper mowing, irrigation, and fertilization are often the most effective weed management strategy (Busey 2003;Engel and Ilnicki, 1969;Hahn et al, 2020). Supplementation of turfgrass seed may only further enhance these highquality fields.…”

“…Too little fertilization can cause turfgrass species to grow slowly and leave ground open for weeds to emerge (Busey, 2003;DeBels et al, 2012;Johnson and Bowyer, 1982), but too much nutrition can cause weed species to proliferate if turfgrass species are struggling (Busey, 2003). There is some evidence that many grass species are more competitive than broadleaf plants at high rates of nitrogen fertilizer; however, some of the grass species that are most competitive, such as Poa annua (annual bluegrass), are undesirable; finding the correct balance of fertilization is also critical (Hahn et al, 2020). High-quality athletic fields with more turfgrass cover and fewer weeds may respond more effectively to overseeding compared with lower-quality fields with little turf and an abundance of weeds.…”

Optimal fine fescue mixture seeding dates in the northern United States

“…Further research to identify postemergence herbi-cides that provide optimum safety on fine fescue seedlings would improve the success rate of spring plantings. However, reliance on herbicide use at or after seeding can be challenging or not option, such as in regions with pesticide bans (Bachand & Gue, 2011;Barzman, & Dachbrodt-Saaydeh, 2011;Campbell & Wallace, 2020;Hahn et al, 2020). There may be a greater chance of success when seeding in the spring if the fine fescue seed mixture contains more F. rubra taxa than F. ovina, because of the better crabgrass suppression abilities observed in F. rubra taxa (Breuillin-Sessoms et al, 2021).…”