Tolerance of Bentgrass (Agrostis spp.) to Postemergence Applications of Metamifop

Abstract

Previous research indicates that metamifop may be an alternative for the control of bermudagrass (Cynodon spp. Rich.) in bentgrass (Agrostis spp. L.) with minimal phytotoxicity; however, only a few cultivars have been evaluated for tolerance. We hypothesize that bentgrass cultivars will respond differently to increasing rates of metamifop. Therefore, the objective of our research was to evaluate the tolerance of several bentgrass cultivars to sequential postemergence applications of metamifop. ‘L‐93’, ‘Penn A‐4’, ‘Penncross’, ‘Seaside II’, ‘Crystal Bluelinks’, and ‘T‐1’ creeping bentgrass (Agrostis stolonifera L.) and ‘SR 7200’ velvet bentgrass (Agrostis canina L.) were established in a greenhouse and sprayed with metamifop at 0, 200, 300, 400, and 500 g a.i. ha−1. Metamifop applications reduced 3‐wk clipping production and increased phytotoxicity of L‐93, Penn A‐4, and Penncross more than Seaside II, Crystal Bluelinks, T‐1, and SR 7200 3 and 6 wk after initial treatment. Seaside II, Crystal Bluelinks, T‐1, and SR 7200 exhibited good tolerance (≤26% phytotoxicity) to sequential applications of metamifop at 300 g a.i. ha−1. The same applications caused ≥47% phytotoxicity to the remaining cultivars. However, methods employed in this research may have affected the level of bentgrass phytotoxicity. Plants grown under greenhouse conditions are often more susceptible to herbicides and therefore exhibit higher levels of phytotoxicity. Furthermore, continuous defoliation indicative of golf course putting greens may stimulate leaf production, thereby reducing bentgrass phytotoxicity associated with metamifop applications. Consequently, additional research is warranted to evaluate the response of bentgrass cultivars maintained under putting green conditions to field applications of metamifop.

Investigating low-dose herbicide programs for goosegrass (Eleusine indica) and smooth crabgrass (Digitaria ischaemum) control on creeping bentgrass greens

“…This was less than the maximum injury of 38% to 74% caused by both rates of fenoxaprop, both quinclorac rates, and topramezone applied monthly (Table 2). Both Parker et al (2015) and Cooper et al (2017) reported similar results where multiple applications of metamifop at 0.2 kg ai ha −1 injured creeping bentgrass by less than 10%. Only one previous study has investigated repeated applications of siduron on creeping bentgrass putting greens.…”

“…Alternate approaches to control summer annual grassy weed infestations on golf putting greens could rely on postemergence herbicides. None are currently registered for use on creeping bentgrass putting greens, but some have shown promise for grassy weed control in other areas or have been assessed for turf tolerance on creeping bentgrass putting greens in published studies (Carroll et al 1992;Cooper et al 2017;Parker et al 2015). In creeping bentgrass mown to 0.6 cm, fenoxaprop, topramezone, and quinclorac are registered to control goosegrass, smooth crabgrass, or both depending on the product (Anonymous 2013(Anonymous , 2018b(Anonymous , 2019.…”

Response of creeping bentgrass (Agrostis stolonifera) and weed species to plant growth regulators

“…ha –1 every 10 d for ultradwarf hybrid bermudagrass ( Cynodon dactylon × Cynodon transvaalensis Burtt‐Davy) cultivars ‘Champion’, ‘FloraDwarf’, ‘MiniVerde’, ‘MS Supreme’, and ‘Tifdwarf’, but only 46% clipping reduction for ‘TifEagle’. Furthermore, differences in tolerance have been reported among creeping bentgrass cultivars to the postemergence herbicides metamifop, fenoxaprop, and methiozolin (Cooper et al., 2017; Henry & Hart, 2004; Hoisington et al., 2014), which may result in variable responses to PGRs.…”