Evaluation of flumioxazin efficacy for annual bluegrass control in warm-season turfgrasses
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Flumioxazin is a protoporphyrinogen oxidase inhibitor that offers an alternative mechanism of action to other chemistries for postemergence annual bluegrass (Poa annua L.) control with residual summer annual weed control in bermudagrass (Cynodon dactylon (L.) Pers.). However, comprehensive research is warranted to effectively utilize flumioxazin in warm-season turfgrass weed control programs. This research evaluated the effects of air temperature, application placement, spray adjuvants, and tank-mixtures with other herbicides on flumioxazin efficacy in turfgrass. Temperatures >10° C and root uptake were critical for maximizing flumioxazin efficacy. Adjuvants did not improve postemergence annual bluegrass control from flumioxazin alone, but tank-mixtures with other herbicides enhanced control. Late winter applications of flumioxazin before greenup caused minimal injury (<20%) to four of the five turfgrasses evaluated. Practitioners may use flumioxazin to avoid herbicide resistance of annual bluegrass populations in long-term management, and provide effective preemergence summer annual grassy weed control.