Creeping bentgrass (Agrostis stolonifera L.) is grown on golf course putting greens and its use as fairway turf is becoming more common. Creeping bentgrass cultivars tolerant to the herbicide glyphosate [N-(phosphonomethyl)glycine] have recently been developed. The ability to control weeds by the application of a nonselective herbicide, such as glyphosate, would ease overall turfgrass management. The conversion of existing putting greens and fairways to glyphosate-resistant creeping bentgrass is an option that many golf course superintendents are likely to consider. However, the conversion of existing turf to a more desirable species or cultivar is costly and would require the golf course to close for a considerable period of time. The objective of these field experiments was to speed the conversion of previously established putting greens and fairways to glyphosate-resistant creeping bentgrass. The best timing for glyphosate application to remove competition from existing grasses was researched on existing putting greens and fairways. Research was also conducted to study the effect of the following factors on conversion of existing putting greens to glyphosate-resistant creeping bentgrass: (i) seeding date, (ii) seeding rate, (iii) surface preparation method, (iv) mowing practices after seedling germination, and (v) N fertility. The best timing for glyphosate application to remove competition from existing turf was before seeding or shortly after seeding. Golf course putting green conversion to glyphosate-resistant creeping bentgrass was most rapid when seed was sown in late summer at 7.3 g m⁻². All surface preparation methods resulted in similar turf cover, but some methods were less labor-intensive and caused less disruption to the putting green surface. Putting green conversion was most rapid when seedlings were mowed for the first time at 6.4 mm and glyphosate-resistant creeping bentgrass was permitted to reach approximately 100% cover before lowering the mowing height at a rate of 0.76 mm wk⁻¹. No differences were observed between N fertility rates of 1.2 and 2.4 g m⁻² wk⁻¹. The results of these experiments suggest that successful conversion of golf course turf to glyphosate-resistant creeping bentgrass can occur with minimal interruption to golf play
