SpeedzoneTM Has the Potential to Control Goosegrass Postemergence with Safety to New Seedlings in Low-Mowed Cool-Season Turfs.

Goosegrass (Eleusine indica [L.] Gaertn.) is a difficult summer annual to manage in cool-season turf. This is especially true in golf course greens and tees where preemergence herbicides are rarely used due to label restrictions or reseeding limitations.  The objective of this research was to evaluate Speedzone™ (0.62% carfentrazone-ethyl, 28.57% 2-ethylhexyl ester of 2,4-D, 5.88% mecoprop-p acid, 1.71% dicamba acid) for use before and after seeding to determine its effect on creeping bentgrass (CBG, Agrostis stoloniferus) and perennial ryegrass (PRYE, Lolium perenne) seedlings.  Previous studies conducted at the University of Nebraska in 2012 and 2013 found that sequential applications of Speedzone™ applied postemergence to goosegrass resulted in high levels of control, with little to no negative impact to established CBG or PRYE at fairway and green heights of cut.  In 2013, a field study was conducted using Speedzone™ at 0.9 kg ha^-1 applied 14, 7, or 0  days before seeding or 7, 14, 21, 28, or 35 days after seeding (DAS) for a total of 8 application timings plus an untreated check.  Plots were power-raked in two directions and then seeded with ‘T1/Alpha’ CBG at 49 kg ha^-1  or a PRYE blend consisting of ‘All Star 3’, ‘Fiesta 4’, ‘Revenge GLX’, ‘Apple GL’, and ‘SR4600’ at 245 kg ha^-1.  Rated 28 DAS, phytotoxicity was detected on CBG from the 14 or 21 DAS.  Treatments applied at seeding and 7 DAS to CBG resulted in lower turf cover than the untreated check when rated on 21 and 28 DAS.  However, all damage in CBG recovered by 35 DAS.  No negative effects were seen in PRYE regardless of application timing. This study is being repeated in 2014 and results will be presented.