Fruit retention is a critical factor for citrus growers, as fruit that remains on the tree to be harvested is the fruit that gets paid for. The challenge has been exacerbated by Huanglongbing (HLB), a disease that significantly increases premature fruit drop, making it essential to identify the key factors influencing fruit retention. In this study, the relationship between fruit size, leaf count, seed viability, and fruit detachment force (FDF) was investigated to better understand what contributes to fruit retention on the tree. A total of 30 fruit per tree in four trees were tagged,fruit size and leaf count on the fruiting branch were recorded and monitored over five weeks., In the second week, Ethephon (150 ppm) was sprayed to induce faster fruit drop. Weekly measurements were taken to track fruit drop. At the end of the study period, the remaining fruit were removed along with their stems to measure FDF, viable seed count, and aborted seed count. The findings indicate a positive correlation between the fruit’s FDF and leaf count, suggesting that fruit with more supporting foliage are more likely to remain attached. Additionally, a negative correlation between the number of aborted seeds and FDF was observed, implying that fruit with more aborted seeds are also more susceptible to detachment. These findings were strengthened by comparing the average values of leaves and aborted seeds between the fruit that had to be manually removed and the fruit that dropped prematurely. The prematurely dropped fruit had a significantly lower number of leaves (9 vs. 16.4 average) and a higher aborted seed number (1.9 vs. 0.9 average). These insights should motivate growers to find therapies that promote leaf growth for a more profitable orchard. The study also points to a need for further investigation into the causes of seed abortion to get a clearer picture of the basic mechanism causing HLB-induced fruit drop.
