Spring frost is the primary cause of yield reduction in southern highbush, representing a significant challenge to blueberry production in the southeastern United States. Plant growth regulators are used as aids in different agricultural industries to either advance or delay growth and development process. Ethephon influences fruit set, size, and yield and has also been used as a tool to delay bloom in order to avoid freeze damage. This study examined the efficacy of ethephon to delay flower bud growth stages in three Southern Highbush Blueberry cultivars (‘Farthing’, ‘Georgia Dawn’, and ‘Kee Crisp’). Ethephon was applied at different concentrations of 200, 400, and 800 ppm, and a control treatment water/surfactant was also included. Flower buds were visually assessed from January until March. No relevant results were found for ‘Farthing’; however, for ‘Georgia Dawn’ and ‘Kee Crisp', ethephon at 800 ppm had the highest effect on delaying blooming development compared to the control. These results suggest that ethephon might delay flower bud growth stages in Georgia Dawn and Kee Crisp, offering potential advantages in reducing susceptibility to spring chill injury.
