In Georgia, cool-season grasses are primarily seeded in fall, rather than spring, to optimize establishment and minimize competition with warm-season annual grassy weeds. However, soil disruption, fertilization, and regular irrigation during establishment of cool-season grasses may promote crabgrass (Digitaria spp.) and goosegrass (Eleusine indica Gaertn.) germination in late summer or fall (Peters et al., 1989). Failure to control annual grassy weeds during establishment of cool-season grasses may lead to subsequent emergence of winter annual weeds such as annual bluegrass (Poa annua L.) that warrant further herbicide use and intensive management for successful culture.
Quinclorac effectively controls crabgrass and may be applied to seedling tall fescue at reduced labeled rates (less than 0.84 kg a.i./ha) but applications do not control goosegrass and may cause excessive injury to creeping bentgrass and perennial ryegrass during establishment (Hart et al., 2004; McElroy and Breeden, 2007). Ethofumesate, mesotrione, and siduron are herbicides used during cool-season turf establishment but inconsistent efficacy, cost, and application regimens limit the effectiveness of these herbicides (Johnson, 1983; McElroy and Breeden, 2007; Moshier et al., 1976). Fenoxaprop is an aryloxyphenoxypropionate (AOPP) herbicide used in cool-season turf for controlling bermudagrass [Cynodon dactylon (L.) Pers.], crabgrass, and goosegrass but applications may injure perennial ryegrass, tall fescue, and other species during establishment (Dernoeden, 1987; Johnson and Carrow, 1993).
Metamifop is an AOPP herbicide used in rice (Oryza sativa L.) for post-control of grassy weeds (Hae-Jin et al., 2002). Compared with AOPP herbicides available in turf, creeping bentgrass has better tolerance to metamifop at rates required for weed control, whereas perennial ryegrass and tall fescue also have acceptable tolerance to applications (Carroll et al., 1992; Dernoeden, 1989; Flessner and McElroy, 2011; McElroy and Rose, 2009; Shim and Johnson, 1992). Metamifop could be useful for controlling annual grassy weeds after seeding cool-season grasses but turf tolerance during establishment has received limited investigation. The objective of this research was to evaluate application timing of metamifop, compared with fenoxaprop, on the establishment of creeping bentgrass, perennial ryegrass, and tall fescue grown from seed.
Anonymous, 2004 Acclaim® Extra herbicide label. Bayer Environmental Sciences, Research Triangle Park, NC
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