1. Please state project objectives and what work was done this quarter to address them: The objectives of this project are: 1, To study the effect of Brs on priming immunity on young, newly planted trees. This will allow to know for how long immune response will last after Br application, so we can adjust timing (number of applications).Spring flush that started in early February was highly syncronized, following the trend we observed during Summer and Fall flushes. We are counting less psyllids per flush after Br application. The canopies are denser than in controls and there is a significantly higher fruit set (30% more fruit) in Br treated trees. In general tree health is improved significantly. Since we are getting more synchronized flushes, we are planning to concentrate Br sprays only at the time of flushing in a set of trees and follow psyllid population, with the idea of limiting Br application only to these moments of flushing and maximum psyllid pressure. 2, To determine the best time of application (frequency) to achieve maximum protection against pests and disease in newly planted trees. Gene expression of genes related to SA pathway, and PR5 and NPR1 is maximum at 30 days, but still significant by 60 days. This confirms past year’s results and indicates that treatments may be performed every other month in young trees. We plan to do a trial with application every other month in the next season.3, To determine the effect of Br application on advancing fruit maturation in both Valencia and Hamlin. We started treatments in Valencia mature fruit-bearing trees on January.We performed two different sets of treatments: biweekly treatment and only once treatment, as in Hamlin. We have noticed this year a great variability in tree health and canopy density in these trees. In general the grove is in decline and most of the trees were categorized as 4 in the disease indexing developed by Jim Syvertsen and Brandon Page for CRDF. Interestingly we saw only a significant effect of Br application on trees that were 2 and 3 in the scale (there were neither 0 nor 1 trees). Fruit was harvested in late April and in the healthiest trees Brix was 9.6 in Br-treated in Mid March as compared to 8.8 in controls. Ratio was also greatly improved. These differences were not significant in trees categorized as 4 in the disease indexing (8.8 for controls as compared to 9.2 in Br-treated). Outreach: -Alferez, F. New tools for growing citrus under endemic HLB. Collier Co Fruit Growers Association, Naples, April 15.-Pérez-Hedo, M.; Urbaneja, A.; Alférez, F. Homobrassinolide Delays Huanglongbing Progression in Newly Planted Citrus (Citrus sinensis) Trees. Plants 2024, 13, 1229. https:// doi.org/10.3390/plants13091229 CRDF project 22-003 is aknowledged in the publication. 2. Please state what work is anticipated for next quarter: We will finish analyzing juice quality and determine gene expression as related not only to plant immunity, but also we are interested in sugar and acid metabolism in response to Br.We are planning to use trees that have been injected with OTC and show symptoms of canopy recovery but not significant improvement in fruit quality to test if Br application can boost internal quality in the next season. This idea came after seeing this year that we get most of the Br effect on increasing Brix on trees with the best canopies (in our plots that are not treated with OTCs). We will focus this quarter on identifying those trees in commercial groves and select trees with different response to OTC in terms of fruit quality to perform the treatments during next season. Finally, for objectives 1 and 2 we will perform a new set of trials: i) concentrate Br treatments in young trees only at the time of flushing and ii) apply Br every other month. 3. Please state budget status (underspend or overspend, and why): Spending continues on track.