Golf Course Management

AUG 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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08.14 GOLF COURSE MANAGEMENT 95 or goosegrass on creeping bentgrass put- ting greens (Table 2). However, research tri- als often indicate good control of one-tiller or smaller crabgrass and goosegrass with fenoxaprop (Acclaim Extra, Bayer) at 3.5 fuid ounces/acre (256 milliliters/hectare) on creep - ing bentgrass putting greens with no appre- ciable injury. Furthermore, newly published research shows that a pre-mixture of 2,4-D + dicamba + MCPP + carfentrazone (Speed - Zone) can control goosegrass without injuring creeping bentgrass putting greens (12). Despite t ese reports, t ese tools are not available to su - perintendents since neit er product is registered for use on creeping bentgrass putting greens. On hybrid bermudagrass putting greens, diclofop (Illoxan, Bayer) and foramsulfuron (for example, Revolver, Bayer) can be used for post-emergence goosegrass control. However, diclofop will no longer be available after De - cember 2014 (Jeff Michel, Bayer Environmen- tal Science, personal communication). For post-emergence crabgrass control on bermu - dagrass greens, no effective options are avail- able, as herbicides such as trifoxysulfuron (Monument, Syngenta) exhibit only marginal activity against crabgrass species. Annual bluegrass Annual bluegrass (Poa annua) is a win - ter annual grassy weed common in creeping bentgrass and hybrid bermudagrass putting greens. Pre-emergence control of annual blue - grass can be erratic because this weed is able to germinate in a wide range of environments (9,10). Post-emergence control is diffcult not only because of the limited number of labeled herbicides, but also because of the possibility of multiple annual bluegrass biotypes persist - ing in putting greens, including both an an- nual-type (P. annua cv. annua) and perennial- type (P. annua cv. reptans). Currently, no herbicides are labeled for selective, post-emergence annual bluegrass control in creeping bentgrass putting green turf. However, sequential applications of plant growth regulators such as paclobutrazol (for example, Trimmit, Syngenta) and furprimi - dol (for example, Cutless, SePRO) often re- duce annual bluegrass populations in creeping bentgrass putting greens and/or control seed - head production (13). Although the products are not labeled for use on putting greens, some turfgrass managers have successfully reduced annual bluegrass populations with the herbi - cides Velocity SG (bispyribac-sodium, Valent) and Xonerate (amicarbazone, Arysta Life - Science) (8,13). Additionally, a great deal of interest exists among golf course superinten - dents in the experimental herbicide PoaCure (methiozolin, Moghu), which can control an - nual bluegrass in creeping bentgrass putting greens. The future of this experimental herbi - cide is still largely unknown at this time. On hybrid bermudagrass greens, trifoxy - sulfuron can be used for post-emergence an- nual bluegrass control, along with foramsul- furon (Revolver), pronamide (Kerb, Dow AgroSciences), and rimsulfuron (for example, TranXit, DuPont). Caution should be heeded when attempting to control annual bluegrass with sulfonylurea herbicides labeled for put - ting greens (trifoxysulfuron, rimsulfuron) as annual bluegrass populations resistant to these herbicides were recently found in Alabama, Georgia and South Carolina (5,11) and these herbicides can move laterally and damage ad - jacent cool-season turfgrasses. Sedge and kyllinga species Sedge (Cyperus species) and kyllinga (Kyl- Creeping bentgrass roots were severely injured in this putting green following an off-label appli- cation of dithiopyr (Dimension 2EW) to a putting green. Roots were severely stunted and clubbed, and rooting depths were extremely shallow causing summer management problems/challenges on this putting green. (Left) Annual bluegrass is a problematic weed because of its ability to produce viable seed under close mowing. (Right) White clover in a creeping bentgrass putting green. linga species) species can invade both creeping bentgrass and hybrid bermudagrass putting greens. These species often invade poor-drain - ing or over-irrigated soils. Kyllinga species tend to tolerate low putting green mowing heights and greater mowing frequencies bet - ter than sedges (4); therefore, kyllinga infes- tations tend to be more prevalent in putting greens. No herbicides are labeled for selective control of either weed species on creeping bentgrass putting greens although some have successfully used spot treatments of halosul - furon (for example, SedgeHammer, Gowan), which is labeled for use on all areas of the golf course except putting greens. On hybrid bermudagrass putting greens, applications of trifoxysulfuron provide kyllinga suppression (Table 2). Broadleaf weeds Although most broadleaf weeds cannot survive at mowing heights used to maintain putting greens, species such as white clover

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