Effects of Spray Volume and Washing On Efficacy of S-ABA Spray Applications

S-ABA is being developed for use on bedding plants and other crops to reduce transpiration and increase time to wilt. The objective of this work was to evaluate two factors that might alter the efficacy of S-ABA in commercial applications. Water use was determined by change in weight over 24 hr. To evaluate the effects of spray volume, S-ABA was applied at 1,000 or 2,000 mg/L to petunia ‘Dreams Appleblossom’ and impatiens ‘Super Elfin XP Blue Pearl’. Spray volumes were 100, 200, 300 or 400 ml/m2. Nonsprayed control plants were included in each experiment. The amount of water used by petunia plants sprayed with 1,000 mg/L in 100 ml/m2 was 57% of amount for control plants. Water use decreased to 38% in plants sprayed at a volume of 400 ml/m2. For impatiens, the amounts of water used by plants in the respective treatments were 74% and 66% of amounts used by the control plants. The effect of 2,000 mg/L of S-ABA at all spray volumes was similar to 1,000 mg/L. In experiments to evaluate the potential for washing off S-ABA with irrigation following a spray application, plants were quickly dipped in water at intervals after S-ABA was applied at 2,000 mg/L. Amount of water used in Salvia ‘Jedi Red’ plants washed at 5, 15, 30 or 60 min after the spray was increased by 53, 24, 24 and 12%, respectively, compared to plants that were sprayed and not washed. For Petunia ‘Dreams Red’, water use amounts were increased by 57, 30, 22, and 19% by washing at 5, 15, 45, and 135 minutes after the S-ABA spray application. These results indicate that overhead irrigation shortly after S-ABA is applied may cause a significant decrease in efficacy. Changes in spray application volume do cause a variation in efficacy, but above 200 ml/m2 the effects are relatively minor.