Two new replicated field trials with Valencia scion were planted with SuperSour-type rootstocks at two locations, one in the east coast area and one in the west coast area. The west coast trial is on high pH soil and should give good information about the tolerance of the SuperSour rootstocks to high pH, in addition to HLB tolerance. Field performance information is being collected on more than 400 new rootstocks in 17 different replicated field trials. Performance attributes being assessed include tree growth, tree health, fruit yield, fruit quality, and tolerance or resistance to HLB and other diseases. New rootstocks are only appropriate for large-scale grower use when outstanding performance has been documented by statistically replicated trials over multiple years. It is anticipated that at least one of the best new SuperSour rootstocks will be released for commercial use within 3 years. In the meantime, outstanding performance has been documented for US-802 and US-942 rootstocks over multiple years in trials affected by HLB, and these rootstocks are available in large numbers through commercial nurseries. During this quarter, analysis was completed on data from several established trials to assess relative rootstock performance, rootstock effects on yield, fruit quality, tree size, and HLB symptom development. A new paper providing a comprehensive comparison of field performance for the new USDA rootstocks with other standard rootstocks, was submitted and accepted for publication in a refereed journal. This publication will be a very valuable reference for use by growers and nurseries making decisions about the best rootstocks to use for new plantings. A new replicated field trial was established to collect detailed information about Valencia tree performance on the most HLB-tolerant rootstocks under optimum management conditions. Focused study in this trial will help to more clearly measure the ways in which tree performance is affected by HLB and estimate the economic viability of commercial production on the most tolerant rootstocks. Trees in the USDA nursery on a large number of advanced rootstock selections, especially SuperSour-type, were continued in propagation for field trials to be planted in 2017. New trials in propagation continue to focus on sweet orange scion, but include some plantings to assess performance with new scions that have better tolerance to HLB. Nursery experiments were conducted with promising new rootstocks to determine nursery-related traits important for commercial use. Cooperative work continued with commercial nurseries involved with micropropagation, to facilitate more rapid deployment of the best new rootstocks. A cooperative project is underway with Dr. Ute Albrecht (UF, Immolakee) to compare trees on rootstocks propagated by seed, cuttings, and micropropagation, so that growers can have confidence that rootstocks propagated by the different methods will have equivalent performance. Cooperative planning continued with UF researchers, to submit grant proposals to USDA NIFA to help fund expanded rootstock research and development efforts. Cooperative grant-funded work continued with UF researchers and a commercial nursery to propagate trees for use in multiple rootstock field trials sponsored by the HLB MAC program.