A study was conducted in 1997, 1998 and 1999 to determine the effect of Pistill (ethephon) at rates of 333, 667 or 1000 ppm and Atrimmec (dikegulac-sodium) at rates of 723, 1446 or 2176 ppm on flower abortion, fruit set and axillary shoot stimulation of Lagerstroemia x fauriei Koehne ‘Tuscarora’ when applied at full flower. Flower abortion increased from 16.7% (1998) and 2.1% (1999) for the control to 84.2% and 64.4% respectively for Pistill (1000 ppm) at 7 days after treatment (DAT). Pistill similarly caused a significant decrease in fruit set during all three experiments with fruit set as low as 2.2% at 14 DAT in 1997 compared to 69.4% for the control. Atrimmec had no effect on flower abortion at 7 DAT in any year except 1999 with 11.3% at the 2176 ppm rate vs 2.1% for the control. Atrimmec also had little effect on fruit set except during 1998 when fruit set at 14 DAT was approximately 40% for all rates of Atrimmec compared to 65% for the non-treated control. Pistill applications resulted in more new shoots than Atrimmec in 1997, and the control in all years. Applications of Pistill at full flower can be an effective tool to abort crapemyrtle flowers resulting in reduced fruit set and increased number of new shoots
2Graduate research assistant.