COS 65-4 - Fertility Impacts Common Lawn Weed Function as a Pollinator Floral Resource in Managed Ecosystems

Abstract: Background/Question/Methods





A healthy turfgrass system can provide a range of ecological functions; however, turfgrass is typically managed as a monoculture through the implementation of several cultural practices and the application of numerous products including fertilizers. Although these inputs are necessary for the production of a healthy, dense turfgrass stand, monocultures provide limited habitat and floral resources for pollinators. Adjustments to fertilization practices could further promote floral production and long-term persistence of common lawn weeds as a pollinator resource, but little is known about the influence of fertility on the competition between weeds and warm-season turfgrass species. Therefore, the objective of our research was to study the impact of fertility on perennial weed growth and floral production in hybrid bermudagrass [Cynodon dactylon (L.) Pers. x C. traansvalensis Burtt-Davy] and centipedegrass [Eremochloa ophiuroides (Munro) Hack.]. Research was conducted at the Athens Turfgrass Research and Education Center in Athens, GA during the summer of 2022. White clover (Trifolium repens L.) and Virginia buttonweed (Diodia virginiana L.) were transplanted into ‘IronCutter’ hybrid bermudagrass maintained at 3.8 cm and ‘Santee’ centipedegrass maintained at 6.4 cm. Four fertility treatments were evaluated within each turfgrass species: [0 g (none), 12 kg (low), 24 kg (medium), and 48 kg N ha^-1 (high) for hybrid bermudagrass and 0 g (none), 6 kg (low), 12 kg (medium), and 24 kg N ha^-1 (high) for centipedegrass]. Treatments were arranged in a randomized complete block design with four replications. Granular fertilizer (18-12-6) was applied by hand every four weeks. Weed lateral spread and floral count data were recorded weekly over three months.


Results/Conclusion


Virginia buttonweed lateral spread and floral production was greater than white clover, regardless of fertility treatment and turfgrass species. Increasing levels of fertility decreased lateral weed spread in hybrid bermudagrass but increased lateral spread in centipedegrass. Floral production of both weed species was least under high fertility when grown in competition with hybrid bermudagrass. On the other hand, floral production of Virginia buttonweed was greatest under high fertility when grown in competition with centipedegrass. In conclusion, each weed species shows potential as a floral resource for pollinators; however, turfgrass competition in response to fertility varies with respect to species and fertility rate. Utilization of low fertility inputs would hinder bermudagrass growth, leading to an open canopy, which would encourage weed infestation. Centipedegrass is a low input species, so exorbitant amounts of fertility only enhance weed competition and further infestation.