Golfdom, November 2017

FROM GOOD TO GREAT annual bluegrass early in the life of a fairway before populations become excessive No treatment effects were visible until May 2012 Table 1 which was after the second year of treatments Record high summer temperatures in 2012 reduced annual bluegrass cover to zero in all plots by August 2012 These two observations reinforce the usefulness of long term annual bluegrass studies in climates like the northern Great Plains with dramatic weather f luctuations that could confound treatment effects Three postemergence applications of Tenacity plus preemergence Barricade applied in August or August and November reduced annual bluegrass cover compared to the untreated control in May 2012 and 2013 and August 2013 and reduced final annual bluegrass cover by more than 75 percent since study initiation Figure 1 These same two treatments also reduced AUPPC by 69 percent to 83 percent compared to the untreated control Three postemergence applications of Prograss plus preemergence Barricade applied in August and November also reduced annual bluegrass cover compared to the untreated control in May 2012 and 2013 and August 2013 reduced final annual bluegrass cover by more than 65 percent from study initiation and reduced AUPPC by 62 percent compared to the untreated control Even though many other treatments performed similarly these were the only three to reduce final annual bluegrass cover and AUPPC compared to the untreated control Our data reinforce that Tenacity has potential for controlling annual bluegrass in the northern Great Plains of the United States We likely could have improved efficacy of postemergence applications of Tenacity with more frequent applications at lower rates or by increasing the amount of N applied with or shortly after application Tenacity applied alone as a preemergence had little effect on annual FIGURE 1 Control of annual bluegrass by preemergence and postemergence herbicide applications in the Kentucky bluegrass experiment in May 2013 bluegrass as Tenacity applied once as a preemergence in August was the only treatment that did not affect annual bluegrass cover at any time during the study Table 1 Tenacity applied as a preemergence in August and as a pre postemergence in November reduced annual bluegrass cover compared to the untreated control rated in May 2012 and thus the November application provided some postemergence control Annual bluegrass on this site appeared to be mostly Poa annua var annua because it was fairly coarse textured light green and a prolific seed producer However the annual bluegrass on this site may have Continued on page 32 November 2017 Golfdom 31 Golfdom com PHOTOS BY ZAC REICHER FIG 1 MATT SOUSEK FIG 2 FIGURE 2 Control of annual bluegrass by postemergence herbicide applications in the creeping bentgrass experiment in May 2013