TANK-MIXED HERBICIDES ON LARGE CRABGRASS (DIGITARIA-SANGUINALIS) AND GOOSEGRASS (ELEUSINE-INDICA) CONTROL IN COMMON BERMUDAGRASS (CYNODON-DACTYLON) TURF

Tank-mix combinations of PRE and POST herbicides were applied to control emerged large crabgrass and goosegrass in common bermudagrass turf. Large crabgrass control was better when MSMA at 2.2 kg ai ha-1 was tank mixed with either pendimethalin at 1.7 kg ai ha-1 (less-than-or-equal-to 85 %) or dithiopyr at 0.3 kg ai ha-1 (less-than-or-equal-to 94%), when compared with MSMA at 2.2 kg ai ha-1 (less-than-or-equal-to 50%) alone. When MSMA plus metribuzin at 2.2 +/- 0.14 kg ai ha-1 was tank mixed with pendimethalin in 1992, large crabgrass control was better (greater-than-or-equal-to 96%) than when MSMA plus metribuzin was applied alone (less-than-or-equal-to 73 %). Quinclorac applied alone at 0.8 kg ai ha-1 controlled greater-than-or-equal-to 94% large crabgrass, but control with diclofop was 32%. There was no increase in control when either quinclorac or diclofop was tank mixed with any PRE herbicide. Methyl ester of diclofop applied alone at 1.1 kg ai ha-1 provided 97 % control of goosegrass at one location, but control was less-than-or-equal-to 62% at two other locations. Goosegrass control was better when diclofop at 1.1 kg ha-1 was tank mixed with dithiopyr at 0.6 kg ha-1 (greater-than-or-equal-to 77%) than when either diclofop (less-than-or-equal-to 62%) or dithiopyr (less-than-or-equal-to 50 %) was applied alone. Goosegrass control was consistently better across years from combinations of dithiopyr plus diclofop at 0.6 +/- 1.1 kg ha-1 (82%) than from combinations of MSMA plus metribuzin with dithiopyr (34%) or pendimethalin (53%). Common bermudagrass injury at Griffin-Spalding Golf Course in 1991 was higher at 1 wk after combination treatments of MSMA plus metribuzin with dithiopyr (46 to 54%) or pendimethalin (50%) than with MSMA plus metribuzin applied alone (26 %). Injury from the combinations was higher from single MSMA plus metribuzin treatment for 4 wk. Similar results occurred at the Georgia Station in 1992 from combinations of dithiopyr with MSMA plus metribuzin.