Our last report mentioned the work evaluating three Pummelo x Citrus latipes hybrids for use as double duty grove windbreak trees that would also attract ACP. Our manuscript entitled Double Duty: Production of psyllid-attracting windbreak citrus trees for the control of Diaphorina citri, the vector of huanglongbing was submitted for publication. Objective(s) pursued: 1. To evaluate the tolerance of newly released/developed citrus cultivars to CLas pathogen.2. To evaluate the tolerance of newly released/developed citrus cultivars to D. citri.3. To determine the mechanism underpinning the tolerance of the newly developed cultivar to HLB. To achieve these objectives, we are challenging these varieties with ACP and graft inoculating them with CLas-infected material to study their responses. We also are extracting and analyzing the leaf polar metabolites, leaf stored volatiles and the released volatiles of new flush via GC-MS. The information received will allow us to predict the success of the variety, similar to our studies on Sugar Belle and Bingo hybrids. In a recent study we investigated the effect of rootstocks on citrus tolerance to citrus greening pathogen by studying the metabolite profile of `Sugar Belle’ mandarin hybrid using gas-chromatography mass spectrometry (GC-MS). The principle component analysis showed that the metabolite profiles of the `Sugar Belle’ mandarin hybrid on the three selected rootstocks were different from each other. These results indicated that rootstocks could affect the primary and secondary metabolites of citrus scions, and consequently could affect scion tolerance to pathogens. The data was published in Plant Signaling and Behavior.Progress on Objectives: Rootstock evaluationsWe received 7 rootstocks for evaluation in the form of seeds, which have been germinated and are growing well: UFR-1, -2, -4, -5, -6, -15 and -17; 46 x 20- 04-6; 46 x 20-04-29Scion evaluations C2-2-1; OLL8; N40-6-3; RBB7-34; Grapefruit 914 – we grafted the budwood from these scions onto UF-2 in November 2019. Lucky – the parents of this cross are Sugar Belle mandarin hybrid and Nava x Osceola (pollen). We have 15 plants of each of the three (the two parents and the hybrid cross) ready for evaluation. We planned to make the first VOC analyses during spring flush but were unable due to the COVID closure. We will continue with evaluations of the mature leaves. Newly released varietiesWe recently received `Marathon’ Mandarin kindly donated from Southern Citrus nursery for propagation and evaluation. Marathon is susceptible to HLB but continues to have good yield after infection. The seed parent was the mandarin variety `Daisy’, which was produced by crossing the mandarin varieties `Fortune’ and `Fremont’. The pollen parent was the small-fruited mandarin cultivar `Seedless Kishu’, which is also known as `Mukakukishu’ in Japan. The leaf and phloem chemical composition will be evaluated on this new variety as soon as we have propagated enough plants for good analytical replication. We expect to have enough by fall to begin analyes.