Effect of simulated mowing on the translocation of mefluidide in perennial ryegrass (Lolium perenne L.)

Young plants of perennial ryegrass (Lolium perenne L.) absorbed approximately 50% of an application of the grass growth retardant, mefluidide, while from 6.5 to 21.9% of the applied dose was translocated during a 2- or 7-day period respectively. After the 2-day period 93.4% of extractable radioactivity was identified as mefluidide. This potentially useful chemical was made unavailable as a result of mowing before or after spraying. Mowing before spraying increased the proportion of cut mature laminae and young laminae, neither of which translocated mefluidide to other plant organs as efficiently as intact, mature leaves. Mowing after spraying removed potentially translocatable mefluidide with the cut mature laminae and reduced mefluidide accumulation in untreated plant parts. While mowing treatments may be aesthetically desirable they probably increase the amount of mefluidide necessary for effective growth retardation.