This fall, many Florida citrus growers are experiencing heavy fruit drop, some even up to 50 percent.
Tripti Vashisth, assistant professor of horticulture at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, recently spoke on this topic. She discussed fruit drop during the first presentation of the new UF/IFAS OJ Break meeting webinar series.
According to Vashisth, there is no single cause for the fruit to drop, rather a multitude of factors.
“Small-sized fruit are more likely to drop,” Vashisth says. She also mentioned that good tree canopy resulted in less fruit dropping.
Originally it was believed that insufficient carbohydrates in the fruit was a leading cause of drop. However, after a preliminary study, Vashisth discovered that increased drop is not associated with starvation of carbohydrates in fruit. Therefore, it is recommended that growers continue good irrigation and nutrition practices throughout the fruit-development stage.
Vashisth also recommends applying gibberellic acid (GA) during the fruit-development period to improve fruit set and fruit retention. She says it is very important to carefully assess the timing of GA applications to avoid possible yield losses. According to Vashisth, more research is underway to evaluate application timing.
Although growers are seeing increased drop among HLB-affected trees, researchers haven’t been able to pinpoint why trees are reacting this way.
Vashisth says the increased drop in trees displaying HLB symptoms could be attributed to off-blooms, which result in new fruit growth while the current crop is already developing. This could cause the new growth and mature citrus to compete for carbohydrates, leading to additional fruit loss.
Overall, good care of trees along with intensive nutrition and irrigation management throughout the growing season are effective strategies in reducing fruit drop.
Vashisth also noted that UF/IFAS has resumed providing growers with regular flower bud advisories and will continue providing them every other week through the spring. To access the advisories, click here.
This article was written by Ashley Robinson, AgNet Media communications intern in Gainesville, Florida.