HLB is known to make citrus roots more susceptible to Phytophthora root rot. It also reduces the efficacy of chemical management of Phytophthora root rot, creating a difficult management scenario. Current Phytophthora management recommendations are based on pre-HLB work done in the 1980s. These three conditions raise the question of whether yield improvement from Phytophthora management is enough to pay for the management costs themselves. The goal of this project is to develop new soil propagule density managment thresholds and recommendations for chemical management of Phytophthora root rot based on ecomonic analysis of yield responses in different soil conditions. Objective 1) Determine if labelled Phytophthora management maintains efficacy in the field on HLB-affected trees for reducing fibrous root loss and improving yield.The spring, early summer and late summer treatments have been put out in the trial plots. Summer Phytophthora soil samples and propagule counts have been taken.In the next quarter we expect to put the last treatment for the year on the fall root flush and take a fall Phytophthora propagule count from all plots. As an expansion of the original scope, we will also rate the blocks for brown rot. This rating will be both a field assessment and a lab based one by taking a weighed subsample of fruit for assessment of brown rot development under optimal conditions in the lab. The weight of fruit sampled for brown rot will be recorded and considered when determining total yield at harvest. Depending on fruit maturity we may start harvesting Hamlins, but this will likely happen in the following quarter. Objective 2) Determine benefit-cost thresholds for Phytophthora treatment on HLB-affected treesAs planned in the proposal, this objective awaits this years yield results to begin calculating benefit-cost based on a combination of change in yield from the previous year and comparison among treatments within blocks.