Hi y’all,
I know a lot of us get the UF|IFAS Citrus Tip of the Week. This week’s (9/28/2026) had a highlight of some of the work I was a part of back when I was at UF. We did a plant growth regulator trial looking at how gibberellic acid (GA) and auxin (2,4-D) could be used to delay preharvest fruit drop in citrus greening affected trees. Trees affected by citrus greening see early and excessive preharvest fruit drop in the few months leading up to harvest. In some cases, we saw >40% of the crop load lost in this preharvest window in severely symptomatic trees. We saw that 2,4-D and 2,4-D in combination with GA could significantly reduce preharvest fruit drop in those trees in Florida.
Up here in Georgia, the story is a little different. Because most of our trees are healthy, we should have very minimal preharvest fruit drop and should not need any sort of mitigation efforts. I have played around with GA as a means of delaying harvest in satsuma, but thus far we’ve seen that the effect is inconsistent and highly dependent on our fall weather. GA delays color development so using GA up here during the late summer/early fall, especially at higher rates, would likely keep our fruit green too late into winter. When we’ve had a warmer fall, GA-treated fruit were still green well into December. Lastly, CitrusFix®, the commercial 2,4-D product used in Florida, is not labelled for use in Georgia and the label is the law!
