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. Yield was collected on the Valencia plots in the last quarter. Irrigations systems for chemigation treatments has been installed and the spring treatment has been put out. In all but one treatment the first treatment of the year is phosphite. We have begun HLB inoculations of Phytophthora postive rootstocks for a greenhouse experiment to determine if the newly labeled chemistries have the same limitation on HLB-affected plants as fosetyl-Al and mefanoxam have shown. Many of the new chemistries are directly effective against Phytophthora in the soil rather than acting after uptake by the roots, so this is likely to reduce the limitations of Phytophthora management in HLB-affected groves and test the hypothesis.