Sept 2018 The objectives for this proposal are1) Conduct ground and aerial applications of fungicides to determine the efficacy and economics of fungicide treatments; 2) Determine if Luna Sensation has enough systemic activity to protect flowers from before they fully develop and open; 3) Determine if the period flowering of trees affected by huanglongbing can be narrowed to eliminate the offseason bloom that contributes to the PFD inoculum increase in groves. Trials were conducted to evaluate further fungicides and fungicide programs. We applied 30 treatments in 3 trials at two locations. One site had Navel oranges and the other was Valencia sweet orange. Only one application was made in each site because there was so little rain during bloom. There was rain during bloom but the temperatures were so low during the rain events that limited disease developed. Fruit counts were collected in July but analysis has not been conducted yet this year. Experiments to validate the Brazilian model were carried out in two citrus producing areas, one with Valencia and the other one with Navel trees. Treatments were equal to the ones tested in 2017. Due to drier and cooler weather the Brazilian model did not recommend any sprays in both orchards. PFD-FAD-based treatments were sprayed twice, whereas three and two weekly applications were performed in the Valencia and Navel groves, respectively. The difference in number of weekly applications was due to the shorter flowering period of the Navel trees. Fruit data were collected in June and there were no statistical differences among the treatments. This again supports the earlier conclusion that the Brazilian model is more conservative and accurate to not indicate sprays when conditions are unsuitable for PFD development. It is hoped that there will be at least one season of where disease occurs to ensure that the model predicts disease as well as it predicts no disease. A presentation was given on the citrus advisory system (CAS) at Citrus Expo in August. For the plant growth regulator trials during this time period, the trees were re-flagged, data were collected on canopy volume (2018) and the treatments were started with applications for Fall 2018. We met to discuss the function of the CAS and if there are any further improvements that are immediately needed. Much of the discussion centered around leaf wetness measurements used in the model and how to make them more robust and reliable, a chronic problem for this type of measurements. To address this question, a small project was initiated to evaluate historical data on how well leaf wetness probes perform compared to models and if models would be sufficient in all situations. Data is being collected.