Annual Bluegrass Control Via Fraze Mowing.

Fraze mowing is a cultural practice designed to remove aboveground biomass to a depth of 5 cm while allowing turfgrass to reestablish via belowground rhizomes. Given that >80% of viable annual bluegrass (Poa annua) seed is found within the top 1-cm of soil, we hypothesized that fraze mowing may be an effective means of non-chemical annual bluegrass control, particularly useful in scenarios where herbicide resistance has limited chemical control options. Field research was conducted from 2015-2017 at the University of Tennessee (Knoxville, TN) on a zoysiagrass (Zoysia japonica ‘Meyer’) fairway naturally infested with annual bluegrass. Turf was frazed mowed (2.5 cm depth) in June of each year with debris collected and discarded. Non-frazed mowed control plots (2.4 x 2.4 m) were included in each replication for comparison. Each spring annual bluegrass infestations were quantified via plant counts. Additionally, soil cores removed from the center of each plot in spring were subjected to soil seedbank analysis at Purdue University (West Lafayette, IN). Germination assays in this analysis quantified the total number of weed seeds in each core, as well as the species, type, and life cycle of weeds present. In field studies, fraze mowing in June significantly reduced annual bluegrass plant counts (26%) the following spring, with seedbank analyses supporting field observations. Our findings suggest that summer fraze mowing can reduce annual bluegrass populations in zoysiagrass turf. However, this technique may not provide acceptable control when used alone and should be incorporated into a diversified weed management program.