The late March cold snap took a toll on some of the early blueberries in areas of Mississippi. From what I have seen and heard, it appears that areas north of Poplarville were hit hardest. I have not seen a lot of damage to blooms here in Poplarville, although reports out of Stone Co. did indicate damage there. Some reports had up to 50% loss on the early Rabbiteye varieties. It also appears that fields with frost protection (i.e. wind machines) had little damage. Application of Gibberellic Acid (GA) may help if pollination was inadequate and fruit set is low. Research has shown that GA application results in decreased berry size and an increase in length of fruit development period (later harvest). The use of GA should be on a case-by-case basis and not used without cause. It is of little value if a high level of natural fruit set was obtained. A common GA product is ProGibb.
Another issue with having freeze damage is botrytis blight. This fungal disease can infect flowers, twigs, and fruit. Cool, wet weather is perfect for development of this disease (it is rainy and cool as I look out my window this morning). The NC Blueberry Journal blog has a nice discussion of this topic that you can find here (http://ncblueberryjournal.blogspot.com/2012_02_01_archive.html). Choices for control include CaptEvate, Pristine, Switch, and Elevate — as well as others. Always read the label before applying. Below are some photos that Jessica Sibley, MSU county extension agent sent me.