The objectives of this proposal are: 1) conduct a field trial using the selected grapefruit seedlings to ensure the productivity of the trees in Florida where HLB is endemic; and 2) evaluate the quality of the fruit produced. Achievement of these goals will produce a more resistant/tolerant variety that could be available in the near future since its use would not require regulatory approval. Based on two year’s graft-inoculation assays in greenhouse with two HLB bacterial isolates and the performance of individual seedlings in the field, four lines of the seedlings (with greater HLB resistance/tolerance) were selected for further propagation on three different rootstock (commercial sour orange, newly selected USDA-sour orange and 942). The fruit quality (Brix, sucrose, glucose and fructose, soluble solids, pH, % TA and total ascorbic acid) of the four selected seedlings showed no significant difference from their maternal trees. The first group of the propagates on three different rootstock from the selections of Scott Grove’s seedling variants were grown at our research farm, Picos Farm, where the plants are under extreme high HLB disease pressure with very aggressive HLB pathogens. These new plantings (July, 2017; Nov, 2017; and May, 2018) showed different disease index, the longer the planting was, the higher the disease index, which was also highly correlated with the titers of Ca. Liberibacter asiaticus (Las) in infected plants. It is worth noting that the new HLB isolate from Picos Farm caused severe HLB disease on most of grapefruit selections of seedlings and bud sports in our latest greenhouse evaluation. Those selections were either resistant or tolerant to the previous HLB isolates we maintained in greenhouse. Prelimilary data showed some of the selections are better than the others with either lower disease index or better canopy growth. In general, the average infection rate was 20.85% for one group of grapefruit plants (470) 20 months after planting, and 5.46% for the other group of grapefruit plants (366) 15 months after planting. The second group of the propagates on three different root stocks mentioned above (Ca. 750 plants) have been budded and grown in our greenhouse, and over 400 plants in 12 combinations have been planted in Scott Grove, and the remainding plants will be planted in September. All of the propagates have been tested for the presence of Las. Propagates carring a low titer of Las will be planted separately and serve as the experiment for “cross-protection”.