Circular 90

The growth regulators chlormequat (Cycocel), paclobutrazol (Bonzi), daminozide (B-Nine) and Bayleton 25WP (triadimefon) were studied for their ability to control plant height in seed propagated tuberous begonia (‘Nonstop’ begonias). Bayleton is a fungicide used for powdery mildew control that also has growth regulator effects. Two ml growth regulator solution was evenly sprayed on each plant two weeks after transplanting. Cycocel (500 parts per million [ppm], 1 mg active ingredient [a.i.] per plant) resulted in 23% shorter plants than the control plants 15 weeks after transplant. Bonzi (5 ppm, 0.01 mg a.i. per plant) treated begonias were 65% and Bayleton (150 mg•liter-1, 0.3 mg per plant) treated plants 43% shorter than the control plants. The number of flowers and shoots was severely reduced on plants treated with Bonzi or Bayleton. BNine was ineffective at the rate of 3000 ppm (6 mg a.i. per plant) for controlling plant height of seed propagated tuberous begonia