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 January 31st report date. Trees have been inoculated for 7 months and we have had a lower and less synchronized infection rate than expected from previous experiments. This led to a modification of the experimental setup to allow for blocking based on time of initial infection. However, we have decided to proceed with the treatments at this time. Irrigation in the first rep of the experiment has been initiated and we are currently collecting and testing leachate for shifts in pH. Physiological measures of canopy and root health have begun to track tree health under the differing irrigation pH environments. Trees for the second experiment have been inoculated and were just sampled to identify how many were successfully inoculated on both sides of the split root system.