July 2020The 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. Nothing further was conducted on the fungicide or CAS validation field trials. We were unable to apply our fungicides during bloom because of the COVID-19 shutdown. We plan to start the planning and set up in the fall for these trials in 2021.We found that in the polar extracts of the pin head, popcorn, and open flowers greatly stimulated the production of conidia compared to sterile distilled water and 2.5% sucrose solution. The length of the germ tubes and their diameter were greatly increase, an unexpected result. There were also a greater propotion that germinated when compared to the water and sucrose solutions. We plan to test to see if this makes the spores more or less infectious on flowers during bloom. Tests with the non-polar extracts are planned. Further tests with specific constituents of the extracts will be tested based on Dr. Wang’s analysis.Flowers of different floral stages were collected and delivered to Dr. Yu Wang’s program so a new set of floral extracts are obtained and the experiments repeated. Since the partial re-opening, Dr. Wang’s program has been able to conduct polar and non-polar extractions of the 3 flower stages (pin head, popcorn, and open bloom). They are analysing the constituents for further experimentation. We are in conversation with the USDA to recommence work in their wind tunnel to conduct the experiment with conidia on flowers for the final comparison. However, it is not clear when the USDA will reopen their facilities. We were unable to acheive our field portions of the project as planned due to the shut down and travel ban. These were extenuating circumstances and we hope to be able to receive a no cost extension so we can undertake the objectives next season. Accordingly, I have removed my technical staff from the project as the are unable to work on the project as had been anticipated.