This project was initiated in 2014 and is focused on understanding the effect of nutrients applied through foliar fertilization programs (FFP) on HLB-affected trees in the Indian River marketing district. Two research trials have been established in commercial mature grapefruit groves in St. Lucie County and a young tree trial is being conducted at the UF-IRREC grove. Grove 1 has ~25 years old of ‘Flame’ grapefruit on Swingle rootstock. Grove 2 utilizes ~7-year-old ‘Ruby Red’ on Sour orange trees. Trial 3 is looking at the effect(s) that foliar fertilizers have on young tree growth and their ability to protract HLB disease symptoms in 2-year-old ‘Ray Ruby’ grapefruit on Kuharske rootstock. Combinations of macro and micronutrient treatments initiated on all three trials in February 2014 and applications have been made quarterly since. During the 2014 and 2015 production seasons, the population of the Asian Citrus Psyllid present in the groves were recorded using sticky traps. The monitoring shows a consistent decrease in the psyllid populations from 2014 until the recent counts in March 2016. The latest data had an average of only 0.02 psyllids per trap. However, the decrease in the psyllid population has not had an effect in HLB titer in the trees. The real time PCR analysis in trees exposed under each treatment has revealed a constant status of tree infection. The latest results (Jan 2016) showed a 100% presence of HLB in trees used in the experiments at the two commercial groves. There have not been any significant differences in the tree growth among treatments durig the 2 seasons in terms of tree volume or canopy density (a>0.05). Nonetheless, the canopy density (evaluated through Leaf Area Index (LAI) measurements) showed a trend of lower LAI in the control treatment compared to the rest of the treatments (receiving foliar applications) in one of the commercial groves. After two harvests, there has been no difference in juice quality parameters among treatments. There has, however, been a significant increrease in the percentage of medium size fruit (sizes 36 and 40) of trees treated with urea, di-potassium polyphosphate, and potassium phosphite compared to the control. This increment is reflected in an increase of 37% in the Gross Packed Value (GPV). (The GPV is the value of fruit when sold from a packinghouse and calculated by the number of fruit produced in each pack size and value of each size of fruit at the time of harvest). It is important to note that, although the other foliar treatments did not have significantly higher GPV compared with control (a>0.05), the GPV of these treatments were all 13%-33% higher and ranged from $85 to $103 per tree, compared to an average GPV of $75 in the untreated control trees.