1. Please state project objectives and what work was done this quarter to address them: The objectives for this proposal are 1) Conduct field trials of new products and fungicide programs for PFD management as well as validation trials for the Citrus Advisory System (CAS); 2) Investigate the reasons for the movement of Postbloom fruit drop (PFD) to new areas and recent major outbreaks; 3) Evaluate methods for initial inoculum reduction on leaves so that early fungicide applications could be more effective and identify the constituents of the flower extracts using omics techniques. We conducted 7 field trials to evaluate how well the Citrus Advisory System (CAS) predicted PFD outbreaks from 2017 to 2021. During this period there were very few PFD outbreaks. In all four years, only one fungicide application was recommended by CAS. This was in 2019 in Fort Meade. In most seasons, there was no significant difference among the treatments, applications recommended by CAS, the older model PFD-FAD, Weekly applications and an untreated control. This indicates that the recommendation of no fungicide application was correct. We also looked at the economic savings of using CAS over the other fungicide application recommendation methods and found there were considerable savings. We also conducted five fungicide trials from 2018 to 2021. Unfortunately, we were not able to make solid conclusions about fungicide efficacy from these trials because the disease was not at high enough levels to statistically separate the treatments reliably. We investigated how far the conidia of Colletotrichum acutatum (syn. C. abscissum) can travel under different conditions: 5, 10, and 20 m/s with and without rain in a laminar flow windtunnel. We also used a turbulent wind tunnel at 5 and 7 m/s with and without rain. We found that the secondary conidia formed on leaves could travel at least 15 m at the 15 and 20 m/s winds with and without rain. This has not been observed before. We were unable to test primary conidia from flowers in the laminar flow tunnel because of COVID-19 and a mechanical breakdown. In the turbulent wind tunnel, the conidia from the leaves did not travel as far but could still move further than if from simple splash with and without rain. We determined that the high polarity fraction of the sugars from citrus (flowers and leaves) can stimulate the germination of C. acutatum conidia nearly as well as the raw floral and leaf extracts. We did not expect leaf extracts to stimulate or stimulate as much as floral extracts, but surprisingly they did. We have tried most of the consituents of the high polarity sugar blend but no single consituent seems to work as well as the original extract. We tested the stimulation of conidia production on leaves with and without fungicide. Ferbam completely inhibits the production of conidia and Headline partially inhibited it. We are trying to figure out why the production of conidia are not stimulated by leaves in the field. Ultimately, we would like to test whether we could suppress inoculum by stimulating it and suppressing it with fungicide before it could infect flowers. 2. Please state what work is anticipated for next quarter: None. This is the final report 3. Please state budget status (underspend or overspend, and why): The budget is closed and no further spending will occur