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Microbial diversity and disease suppression in turfgrass landscapes under intensive management

Michael Millican: University of Wisconsin

<div>Maintenance of turfgrass requires routine applications of nitrogen fertilizer, herbicides, insecticides, and fungicides that are beneficial for the turf stand but have broader ecological costs. Understanding the influence of nitrogen and pesticide applications on the turf-associated microbiome is a critical step in understanding how these maintenance regimes impact the surrounding ecosystems and the health and sustainability of the turf phytobiome. High and low acute toxicity herbicides, insecticides, or fungicides were sprayed on tall fescue in Madison, WI and soil samples taken at 0, 1, 3, 7, 14, and 21 days. Nitrogen was applied to creeping bentgrass at 0, 9.76, and 29.29 kg N/ha applied bimonthly and soil cores were removed every four weeks. Bacterial and fungal diversity in both studies was assessed using the 16S rRNA and ITS-2 DNA regions, respectively, and sequenced using Illumina MiSeq. Raw sequencing data was processed using Mothur and statistical analyses were carried out in R. Increasing nitrogen input to 29.29 kg/ha results in reduced dollar spot severity nearly to fungicide treated turf. With our study we strive to understand how pesticides, pesticide toxicity, and nitrogen fertilizer impacts microbial diversity and any implications it has on turfgrass disease suppression. These results will deepen our knowledge of how management practices affect the turf phytobiome and help create more sustainable management strategies moving forward.</div>