Fruit set of rabbiteye blueberry (Vaccinium ashei) after subfreezing temperatures

Plants of 'Brightwell' and 'Tifblue' rabbiteye blueberry (Vaccinium ashei Reade) were subjected to 0, -1, -3, or -4.5 degrees C for 1 hour during flowering. After treatment, half of the plants were exposed to bees (Bombus sp.) only, and half were exposed to bees and received applications of GA(3). Fruit set of both 'Brightwell' and 'Tifblue' pollinated by bees declined sharply after exposure to -1 degrees C for I hour, but there was no visible damage to corollas, styles, and ovaries. Fruit set of GA(3)-treated plants of both cultivars equaled that of control plants (plants having no cold exposure) at temperatures greater than or equal to-3 degrees C. Both pollinated and GA(3)-treated plants had less than or equal to 2% fruit set after exposure of flowers to -4.5 degrees C,Both prefreeze and postfreeze applications of GA(3) were beneficial for fruit set, Assessment of Rower part damage at the different temperatures indicated corollas were most sensitive to freeze damage, followed by styles, and then ovaries, Results suggest fertilization and fruit set of pollinated rabbiteye blueberries can be greatly impaired by even mild freezes (-1 to -2 degrees C), whereas, appropriately timed applications of GA(3) can result in little reduction in fruit set even after moderate freezes (-3 to -4 degrees C) of blueberries during bloom. Chemical name used: gibberellic acid (GA(3)).