Seasonal root sampling continues in two field sites for root density and root growth. We are collecting a second year of root growth data from Hamlin/Swingle and have 1 year of root growth data on Valencia/Swingle. Results so far emphasize the need to use treatments that improve root longevity as the main method of managing HLB root loss. Root growth stimulation is unlikely to improve root density. Preliminary tests of root tubes are complete and easy observation of root growth and root dieback have been confirmed. This will allow for more rapid quantification of root growth and death using nondestructive sampling so that the same roots can be monitored over time. The root tubes have been installed in treated and untreated plots of a thermotherapy trial to combine efforts and provide both basic disease information and treatment effects on the root system. Sampling at a rootstock trial site continues. Only one rootstock tested to date has shown a significant difference in response to HLB. Initial sampling at a second rootstock trial site has begun. This will allow comparison of some of the rootstocks on Ridge and Flatwoods soils. We continue to monitor the most promising rootstocks identified in the field trial to HLB using rhizotrons in the greenhouse. A second set of rootstocks is ready for testing in rhizotrons as soon as greenhouse space is available from the breakdown of the first set. Changes in image acquisition and soil type have been tested to improve the data analysis steps in these followup experiments. The first experiment is ready for takedown, but is awaiting some final root collections for phytohormone and microscopic analysis. Method development to characterize the mechanism by which Liberibacter causes root death continues with a second round of samples to be collected shortly with improved tissue selection to avoid variability found in the first attempt at microscopy analysis of cell death.