TALL FESCUE TOLERANCE TO TOWER (DIMETHENAMID) AND FREEHAND (DIMETHENAMID + PENDIMETHALIN). D... Gomez de Barreda* and P. McCullough, Polytechnic University of Valencia, Valencia, Spain (26)


Freehand (1.75G) contains dimethenamid (0.75%) and pendimethalin at (1%) and is being evaluated for potential use as a preemergence herbicide in turf.  The objective of this field experiment was to investigate tolerance of a ‘Talladega’ tall fescue field established in fall 2010 to spring applications of Freehand in 2011.  Treatments included Freehand at 0, 2.94, 3.92, 5.9, and 7.85 kg a.i./ha, Tower 6L (dimethenamid) at 1.68 and 3.36 kg a.i./ha, and Pendulum 3.8ME (pendimethalin) at 2.24 kg a.i./ha.  All treatments were applied May 16 and again on June 28, 2011. Freehand injured tall fescue 11 to 34% by 6 weeks after initial treatments (WAIT) while all other treatments caused ≤15% injury.  After the second application, tall fescue injury from Freehand ranged 19 to 50% by 10 WAIT but sequential applications of Pendulum and Tower caused <10% injury. Freehand rates >2.94 kg a.i./ha reduced turf quality on several dates from the untreated but Tower and Pendulum applied separately did not reduce quality.