Methods and species for conversion of Kentucky bluegrass rough to no-mow, low-input turfgrass areas

Abstract

With golf course water, fertilizer, and pesticide restrictions on the rise and labor costs continuing to increase, golf course superintendents are looking for ways to reduce maintained Kentucky bluegrass (Poa pratensis L.) rough. The objective of this study was to (i) compare several methods for converting Kentucky bluegrass roughs to no-mow, low-input grasses and (ii) determine the best turfgrass species that provides a playable and aesthetically pleasing turfgrass stand for this type of conversion. Five grass species and five conversion methods were evaluated at two locations in Minnesota (Maple Grove, MN and St. Paul, MN). Data collected included visual stand quality, tendency for lodging, inflorescence counts, biomass production, Kentucky bluegrass regrowth, and broadleaf weed invasion. At Maple Grove, the fumigation treatment provided the highest visual stand quality ratings and the sod removal treatment at St. Paul provided the highest visual stand quality. Only sheep fescue (Festuca ovina L.) was able to provide acceptable visual stand quality by Year 2 and only at St. Paul. Chewing’s fesuce (Festuca rubra L. ssp. commutata Gaudin) and strong creeping red fescue (Festuca rubra L. ssp. rubra) were best at resisting broadleaf weed invasion at both locations. Hard fescue (Festuca brevipila Tracey) was best at resisting lodging along with strong creeping red fescue in Year 2 at both locations. Due to its perennial nature and rhizomatous growth habit, it may be difficult to obtain complete control of Kentucky bluegrass when converting to a no-mow, low-input area. Selective removal of Kentucky bluegrass regrowth may be needed when converting to low-maintenance grasses. Previous studies have shown that fine fescues (Festuca spp.) have a high tolerance to the herbicide sethoxydim (2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) and it may provide the answer when needing to selectively remove Kentucky bluegrass from fine fescue. The objectives of this second study were (i) to compare the tolerance of cool-season turfgrass species and cultivars to sethoxydim and (ii) determine species tolerance at different application rates. Four herbicide rates (0.0, 1.315, 2.630, and 5.26 L·ha-1) were applied to fifteen coolseason grasses (5 Kentucky bluegrass cultivars, 3 tufted hairgrass (Deschampsia cespitosa [L.] Beauv.) cultivars and selections, ‘Gator’ perennial ryegrass (Lolium perenne L.), ‘Plantation’ tall fescue, (Festuca arundinacea Schreb.), a native prairie junegrass breeding line (Koeleria macrantha [Ledeb.] Schult.), and 4 species of fine fescues. All fine fescue species tested in the study were unharmed by all rates of sethoxydim. Surprisingly, tufted hairgrass showed some tolerance to sethoxydim in 2008 and performed better in 2009. Tall fescue was not tolerant in 2008, but showed some sethoxydim tolerance in 2009. All other species saw individual plant quality decline below acceptable levels by 5 WAT.