Field and laboratory experiments were conducted in New Jersey to investigate the influence of spray adjuvants on foliar absorption and efficacy of bispyribac-sodiurn on annual bluegrass, creeping bentgrass, and perennial ryegrass. In laboratory experiments on annual bluegrass, C-14-bispyribac-sodium without an adjuvant had 25 foliar absorption by 8 h after treatment, whereas absorption increased to 45, 46, and 75 when applied with crop oil concentrate, nonionic surfactant, and methylated seed oil, respectively. In creeping bentgrass fairways, sequential bispyribac-sodiurn applications at 37 g ai/ha with spray adjuvants controlled annual bluegrass similarly to 74 g ai/ha applied sequentially without adjuvants. In perennial ryegrass, treatments with methylated seed oil and nonionic surfactant required 25 and 41 lower bispyribac-sodium rates, respectively, to obtain annual bluegrass control levels comparable to bispyribac-sodium rates without adjuvants. Spray adjuvants did not exacerbate turf-grass discoloration from bispyribac-sodium. Overall, spray-adjuvant use with bispyribac-socliurn may allow practitioners to reduce application rates and enhance efficacy for annual bluegrass control.
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