Reducing fruit drop by altering hormonal responses within the tree through nutritional and hormonal therapies: a mechanistic affordable approach

Reducing fruit drop by altering hormonal responses within the tree through nutritional and hormonal therapies: a mechanistic affordable approach

Report Date: 11/15/2023
Project: 21-007   Year: 2023
Category: Horticultural & Management
Author: Alferez Fernando
Sponsor: Citrus Research and Development Foundation

1. Please state project objectives and what work was done this quarter to address them: Specific objectives are:1) To determine the right timing for Zn and K treatments to minimize fruit drop.2) To determine effects of GA3 and 2,4D applications on fruit retention when applied at different times during fruit development.3) To develop a strong and proactive outreach program. For objective 1 we did a new set of treatments by the end of September in Hamlin as we did last year. This date of treatment was the one that got best results last season in terms of yield, despite the effects of hurricane Ian. As before, every set of treatments is performed in an independent replicated block, so treatments are applied only once, to assess the best timing to achieve the best results. Trees under Zn and Zn+K treatments continue having greener canopies. This is consistent with effects we saw last year. Also, we are performing canopy analysis by using the ImageJ program. In Hamlin, trees treated with Zn  continue to have significantly more dense canopies and more canopy volume than controls. These measurements have been done also for objective 2, and we are analyzing data. For objectives 1 and 2 we are also analizyng foliar nutrient concentrations.We see less oxidative stress levels in trees treated with Zn and Zn+K.Fruit drop is being now monitoired weekly. We still don’t see differences in treatments but this is usually seen in October-November. Objective 3:-Optimizing foliar sprays of zinc and potassium to prevent fruit drop, by Fernando Alferez, Daniel Boakye, Murillo De Sousa and Pablo Orozco. Citrus Industry, Tip of the Week, October 2023.  2. Please state what work is anticipated for next quarter:  Treatments for objectives 1 and 2 will continue as programmed in Hamlin. We will continue fruit drop assesments weekly. Sampling will continue as well and we will finisnh data analysis of samples analyzed in the last quarter for objectives 1 and 2. Harvesting of Hamlin will be done in December-January. Treatments in Valencia will start.   3. Please state budget status (underspend or overspend, and why):  Budget is on track  


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