Project Number: 6618-21000-015-00
Project Type: Appropriated

Start Date: Oct 01, 2012
End Date: Dec 31, 2013

Objective:
1. Evaluate citrus scion cultivars and advanced selections with potential for commercial use, identifying genotypes that will survive to bearing age and produce high quality fruit for the fresh and juice markets. 2. Determine horticultural and physiological factors affecting citrus trees propensity to succumb to HLB (huanglongbing).

Approach:
Sustainability of the U.S. citrus industry, especially in Florida, is currently threatened by Huanglongbing (HLB), a disease associated with the bacterium Candidatus Liberibacter asiaticus (CLas) and its vector, the Asiatic citrus psyllid. HLB debilitates trees, reduces yield, ruins fruit quality, and eventually kills trees. Young trees are particularly susceptible to HLB, making the establishment of new orchards challenging. The foundation of sustainable citrus production in the face of HLB will be cultivars, both scion and rootstock, that are able to survive to bearing age and that produce high quality fruit for the fresh and juice markets. Identification of citrus types resistant or tolerant to HLB and acceptable to the market will require research at various stages of tree development; however, young tree survival, by default, is the first step in the process. If trees can survive to bearing age, the next step in the evaluation of promising genotypes is horticultural performance including susceptibility to other diseases, cropping ability, and fruit quality. Evaluation of fruit quality for genotypes which survive and produce a crop is essential to determine if new hybrids or transgenic plants meet established standards. Finally, when promising selections have been identified, replicated field trials will be the conducted to determine worthiness for eventual release. Protection and preservation of the invaluable advanced selections and breeding lines which exist only in the U.S. Horticultural Research Laboratory citrus breeding program are essential to this program; novel methods for pathogen elimination, scion evaluation, and germplasm conservation will be tested. Enhanced production efficiency, health, and value of the U.S. citrus crop will be outcomes of this research.