This project evaluates young tree protection from ACP/HLB using approaches to integrate ground cover, insecticides, and irrigation management at three locations 1) Southwest Florida Research and Education Center (SWFREC), Immokalee, FL, 2) Citrus Research and Education Center (CREC), Lake Alfred, FL, and 3) Florida Research Center for Agricultural Sustainability, Vero Beach, FL. Treatments of 1) soil-applied neonicotinoids interspersed with sprays of a different mode of action insecticides on a calendar basis, and 2) rotation of insecticide modes of action sprayed twice on each major flush were applied to trees on UV reflective and bare ground at the three locations. The irrigation deficit treatments were implemented at SWFREC and CREC locations to trees on UV reflective and bare ground to synchronize flush to make insecticide spray applications twice on each major flush.We monitored flush abundance and psyllid populations at CREC and SWFREC. Analysis of data at CREC revealed that ACP adult abundance responded to all the factors tested, including ground cover (bare vs. mulch) and insecticide application timing (calendar vs. flush applied). There were fewer ACP adults on trees with mulch than with bare ground. Trees with insecticides applied based on a calendar schedule also had fewer adult ACP than those that experienced insecticide applications based on flush. Lastly, ACP adult abundance was weakly but positively dependent on flush abundance, which was impacted by the ground cover treatment and the date of sampling. On average, there was fewer flush observed on bare ground trees than on mulched trees. We have reported similar findings from the data collected at SWFREC on these variables in the previous reports. However, effects during this quarter were not as pronounced as observed at the CREC location. We also measured trunk growth and analyzed HLB incidence in the trees at SWFREC. The diameter of the trunk of the rootstock and scion of the trees on the mulch was significantly more than the trees on the bare ground. An average rootstock diameter of 45.6 mm on the mulch and 39.7 mm on the bare ground was observed. Scion diameter averaged 29.9 mm on the mulch and 26.5 mm on the bare ground. As part of this project, we are also evaluating tree defenders on trees planted on bare ground. Interestingly, the trees’ rootstock or scion trunk diameter on mulch did not differ significantly from the trees covered with tree defenders on bare ground. HLB incidence was significantly higher in the trees planted on the bare ground compared to the trees on mulch, an average of 55% and 22% HLB positive trees, respectively; however, disease incidence did not differ between the trees treated with insecticides applied based on a calendar schedule (foliar sprays interspersed with soil applications) and those that experienced insecticide spray applications based on flush. Data on soil moisture and irrigation treatments have been continuously monitored every 30 minutes at the CREC and SWFREC sites. The next report will provide some updates on the status of available water in the treatment with regular or deficit irrigation. A significant number of trees at the Vero Beach locations were damaged by rains and died. We have already replaced 100 trees and are in the process of replacing another 50-60 trees. One challenge observed to-date is the difficulty in imposing irrigation regime (regular over deficit irrigation) treatments at this location due to the presence of a perched water table that results in water upflux, confounding the effect of irrigation in the reflective mulch treatments. At this point, we have discussed with the collaborator and are maintaining the same level of irrigation to trees on mulch and bare ground to be able to see any differences between the main treatments and wait to evaluate deficit irrigation treatment to synchronize flush at a later time based on findings.An economics student was hired that will work on this grant, though but funded through other sources. The student had a delayed start in the fall semester but has been working on this project and has now completed a draft of the survey instrument and begun data collection for partial budgeting analysis. The instrument has IRB approval and will go through grower and team reviews in 2021. Because of COVID-related travel restrictions, the team has to change the survey approach. Project spending was delayed but will begin with funding the new survey approach and hiring a postdoc to conduct analysis and help to create educational material. We will continue our activities reported here into the next quarter.