Annual Bluegrass: Emergence of Viable Seed in Various Putting Green Sites and Soil Removal Depths

Abstract

<jats:p>A major concern with many creeping bentgrass (<jats:italic>Agrostis stolonifera</jats:italic>) putting greens is annual bluegrass (<jats:italic>Poa annua</jats:italic>) invasion. The study was designed to garner data regarding the depth of soil removal needed to reduce annual bluegrass seedling emergence in a newly renovated putting green. Research was conducted in different seasons (summer and fall) to evaluate seedling emergence across five soil removal depths in four sampling sites. Cores were collected from four golf courses in southeastern Michigan, subdivided into different soil removal depths, potted in sterile soil media, and established in a growth chamber. Results suggest that excavating soil to a depth of 1.0 inch or, more prudently, to a 1.5-inch depth could minimize annual bluegrass competition in a creeping bentgrass putting green. Annual bluegrass emergence was observed to be greatest in the upper soil depths (0.5–1.5 inches) in both seasons, with minimal emergence (&lt;1.1 plant/0.2 ft<jats:sup>2</jats:sup>) below the 2.0-inch soil removal depth treatment.</jats:p>

Nonchemical annual bluegrass (Poa annua) management in zoysiagrass via fraise mowing

“…The site used in our experiment was a 4-yr-old sward of warm-season turf in Tennessee where annual bluegrass is a problematic weed but a smaller component of the turf sward than in cooler climates. As such, although data in this present experiment do not support that fraise mowing is highly efficacious for annual bluegrass removal from the soil seedbank of warm-season turf, fraise mowing may prove to be effective in removing annual bluegrass from the seedbank of cool-season turf as suggested by Green et al (2019).…”

“…In the seedbank analysis, 235 annual bluegrass seedlings were counted indicating that proportionally, the majority of the annual bluegrass seed remained in the soil following fraise mowing. Again, these results were surprising considering published data on cool-season turfgrasses suggest that the majority of the annual bluegrass in the seedbank resides in the top 1 cm (Branham et al 2004) of soil in cool-season golf course fairways or the top 1.3 cm (Green et al 2019) of the soil in cool-season golf course putting greens. It is likely that seedbank dynamics and seed distribution in the soil profile is different between climates with increased annual bluegrass.…”

“…It is likely that seedbank dynamics and seed distribution in the soil profile is different between climates with increased annual bluegrass. Past research on annual bluegrass seedbank dynamics (Branham et al 2004;Green et al 2019;Watschke et al 1979) was conducted in cool-season turf swards in Illinois, Indiana, Michigan, and Pennsylvania with a high percentage of annual bluegrass. Additionally, some of the sites previously studied were golf course turfs that were 90þ yr old.…”

Fairway Renovation with Fraise Mowing Cultivation and Dazomet Fumigation

“…Based on the recommendations of Branham et al (2004) and Green et al (2019), excavating the upper 1.3 to 3.8 cm of soil should remove the majority of the annual bluegrass seedbank. In these experiments, fraise mowing to a depth of 1.9 cm was inadequate and failed to provide complete or acceptable levels of annual bluegrass control.…”

“…In one season alone, a single population can produce hundreds of thousands of seeds per square meter (Lush, 1988). A majority of those viable reside at shallow depths (Branham et al, 2004;Green et al, 2019). To prolong the sustainability of a production system, the seedbank must be managed (Norsworthy et al, 2012).…”