Golfdom, November 2017

damage Annual bluegrass control hasnt been thoroughly researched in Kentucky bluegrass fairways Researchers have shown that Tenacity mesotrione Syngenta has potential as a postemergence herbicide to control emerged annual bluegrass However Tenacitys label does not specifically list postemergence control of annual bluegrass However it is labeled for preemergence suppression of annual bluegrass and for use on Kentucky bluegrass fairways Work in Indiana and Illinois indicated that optimum annual bluegrass control in the fall resulted from three applications of Tenacity at 3 or 5 f l FROM GOOD TO GREAT oz acre applied at 14 day intervals starting in mid to late September Three fall applications of Prograss ethofumesate Bayer has been the standard for controlling annual bluegrass in Kentucky bluegrass and or perennial ryegrass fairways Some fairways in Nebraska and farther west are creeping bentgrass Agrostis stolonifera L In creeping bentgrass Velocity bispyribac sodium Valent currently is the industry standard for postemergence annual bluegrass control and has been thoroughly researched Multiple applications on 2 to 3 week intervals are highly effective for annual bluegrass control and Velocity becomes more effective on annual bluegrass and less phytotoxic on creeping bentgrass at temperatures above 68 degrees F Current label recommendation for Velocity 176WSP is up to four applications at 6 fl oz acre applied at 21 day intervals on fairways with relatively low populations of annual bluegrass Unfortunately the status of Velocity currently is questionable as Valent is reassessing the herbicide in the turf market Hopefully Velocity will remain a viable option for superintendents HOW WE DID IT Kentucky bluegrass fairways The Kentucky bluegrass study was located at Firethorn Golf Club and used a low mow Kentucky bluegrass blend NuDestiny Everglade 4 Season Solar Eclipse and Beyond seeded in 2009 Soil type was Aksarben silty clay loam and maintenance included mowing three times per week at 050 inch with clippings returned 2 lbs nitrogen N 1000 sq ft year preventative white grub control and Dimension dithiopyr Dow AgroSciences applied in spring for crabgrass control The Kentucky bluegrass study consisted of 11 late summer and fall treatments including combinations of herbicides applied as preemergence Barricade 65WDG prodiamine Syngenta or Tenacity and or postemergence Tenacity or Prograss 15EC for annual bluegrass control Table 1 A non ionic surfactant Induce Helena Chemical was included with all Tenacity applications at 025 percent v v We applied treatments starting in August 2010 with identical treatments repeated in 2011 and 2012 over the same plots Creeping bentgrass fairways The creeping bentgrass study was located at Omaha Country Club which has approximately a 5 year old creeping bentgrass blend T1 Alpha and Crenshaw Soil type was a Monona Continued on page 30 percent change from initial percent cover and Area Under the Kentucky bluegrass fairway in Lincoln NE May 2012 Aug 2012 May 2013 Aug 2013 Aug 2013 Aug 2013 percent cover percent change AUPPC 19 bc 0 53 a 38 a 206 a 21092 ab 11 cd 0 36 ab 30 ab 185 a 14856 a d 20 abc 0 16 bc 17 bcd 8 bc 15972 a d 26 ab 0 24 bc 16 bcd 6 bc 17349 a d 17 bc 0 8 c 8 d 46 bc 12969 a e 34 a 0 8 c 7 d 58 c 18577 abc 22 abc 0 9 c 13 cd 16 bc 14331 a e 9 cd 0 7 c 3 d 76 c 6910 de 16 bcd 0 16 bc 14 cd 5 bc 10931 b e 3 d 0 5 c 2 d 78 c 3803 e 9 cd 0 10 c 6 d 65 c 8694 cde 29 ab 0 46 a 25 abc 85 ab 22652 a November 2017 Golfdom 29 Golfdom com