The objectives of this study are to identify optimal pH range for root function and minimize root turnover on HLB-affected rootstocks and how uneven pH levels in the root zone (e.g. irrigated vs. row middle portions of root system) affect the overall health of the tree. This is being done in a split root system in the greenhouse where pH of different parts of the root system can be controlled an maintained. The following progress reported is based on a October 31st report date. The breakdown of the 2nd experiment testing different irrigation pH’s on each half of the split root system (to mimic irrigated and non-irrigated root zones) is complete. Data is being analyzed and samples for RNAseq are being prepared. The 2nd repetition of the 1st experiment is underway to confirm the results that US942 becomes highly sensitive to low pH (5.5) when infected with HLB (root damage and excessive root leakage causing irrigation leachate pH to increase. We also expect to partially confirm this finding in the ongoing data analysis of the 2nd experiment.