ACCELERATING CITRUS SCION CULTIVAR DEVELOPMENT AND TESTING

Establish and utilize priority parent trees in parent-tree screenhouse at USDA Whitmore Farm (jointly funded by Florida Citrus Research Foundation and the Citrus Research and Development Foundation) to permit hybrid production without compromise from winter injury or disease. Techniques to manage tree growth will be evaluated to maintain trees within restricted spaces. Trees in the screenhouse will also provide information on parthenocarpy and if not parthenocarpic, provide opportunities to determine suitable pollenizer. Establish and maintain priority seedlings on the juvenility trellis. Most material will be placed inside the screenhouse so that resulting selections for further testing will not require CTV-cleanup, but plans must include room for future seedlings. Trying new liners to see if they perform better than material grafted onto older established Swingle. Germinate and grow seeds of 500+ mandarin hybrids, 500+ orange-like hybrids produced in 2014 crosses many of which will segregate for genetic seedless from using Kishu and Kishu hybrids as pollen parents. Bud or graft trees into screenhouse/juvenility trellis as soon as possible. Irradiate large numbers of 5-51-2 buds and prepare nursery trees for planting in commercial sites and evaluation for low-seeded variants. 5-51-2 displays marked tolerance to Huanglongbing (HLB) and has excellent fruit quality. Grow out trees of irradiated priority mandarin-type and grapefruit hybrids. Coordinate with NVDMC to have planted in grower fields. Continue screening existing hybrids at both the Ft. Pierce and Leesburg Farms. Select buds of priority selections (irradiated and conventional hybrids) at Ft. Pierce, treat with antibiotics and propagate promising selections. Follow CLas (Candidatus Liberibacter asiaticus, the HLB pathogen) levels to verify HLB-free. Continue to pass priority selections through Peggy Sieburth¿s shoot-tip grafting program and establish material in the parent-tree screenhouse at USDA Whitmore Farm as well as coordinating second tests in collaboration with NVDMC and Dr. McCollum. In 2015, there will be a reduced focus on new hybridizations and greater focus on evaluation of advanced hybrids in coordination with Greg McCollum. Hybridizations will focus on creating new hybrids which capitalize on advanced USHRL selections, especially with HLB-tolerance, as seed parents and Kishu-Hybrids as pollen parents. Mandarin, sweet orange-like and grapefruit-like progeny are targeted.