Allelopathic potential of cool‐season turfgrass species as an alternative management strategy for weed control

Herbicides are a common input in turfgrass systems. Selecting turfgrass species that have either the ability to out‐compete weeds or inhibit their germination and establishment is a primary integrated weed management strategy to reduce herbicide use. The objective of this experiment was to assess the allelopathic potential of common cool‐season turfgrass species ( Festuca arundinacea , Festuca brevipila , Festuca rubra ssp. rubra , Festuca rubra ssp. littoralis , Festuca rubra ssp. commutata , Lolium perenne , and Poa pratensis ) on common turf weeds ( Digitaria sanguinalis , Eleusine indica , Poa annua , and Taraxacum officinale ). Greenhouse and laboratory experiments were conducted to evaluate the effect of turfgrass competition, leaf extracts, and soil leachates on the germination and growth of weed species. Leaf extracts and soil leachates of turfgrass species generally had more effect on radicle growth than on germination and coleoptile (or hypocotyl) growth. Cool‐season turfgrass leaf extracts did not suppress the gemination of P. annua , D. sanguinalis , or E. indica . P. pratensis leaf extracts were effective in suppressing Taraxacum officinale germination and emergence. Poa annua emergence and development were significantly lower when seeded into dense, established cool‐season turfgrasses. All turfgrass species were equally inhibitory when the turf was dense and competition was present. Limited allelopathic effects were noted in this experiment. Rather than picking a turfgrass species for potential allelopathic effects, these results point to the more effective weed management strategy of maintaining a dense and robust turf sward capable of outcompeting weeds for light, nutrients, and water. The effects of turfgrass leaf extracts and soil leachates on germination of weed species were less prominent and often not significant. Turfgrass leaf extracts had more effect on radicle growth of germinating weed species than soil leachates. A dense and healthy cool‐season turf sward can inhibit annual bluegrass emergence.