ASHS 2025 Conference

The citrus industry in Florida has been decimated by huanglongbing (HLB), a disease vectored by the Asian citrus psyllid. Industry standard budlines of sweet orange in Florida have all been deemed susceptible to HLB and do not produce profitable yields at the vast majority of commercial groves. Symptoms of HLB include low yield, premature fruit drop, stunted growth, poor fruit and juice quality, blotchy mottle of leaf tissue, and eventual tree decline, dieback, and tree death. There is not yet a therapy or treatment that has cured this disease. A relatively new selection of sweet orange called 'OLL-8' has shown increased tolerance to HLB as measured by yield, fruit quality, tree growth and multispectral imaging metrics. The 'OLL' acronym represents the names of Orie and Louise Lee, who were citrus farmers in the State of Florida for decades. The 'OLL-8' sweet orange is a somaclone of the original 'OLL' tree that was found in St. Cloud, FL. Evidence of the enhanced tolerance of OLL-8 versus standard 'Valencia' and 'Hamlin' will be presented in the form of fruit and juice quality, yield, tree growth and size, and multispectral drone imagery data, including normalized difference vegetation index (NDVI). The 'OLL-8' sweet orange outperformed both conventional scions at multiple sites over multiple seasons in Polk County FL. Several drone flights were used to determine tree size and health over time. The results demonstrate the possibility of enhanced plant performance with the use of somaclonal variation in sweet orange in the HLB environment. More research is needed to confirm 'OLL-8' sweet orange's tolerance, and if confirmed, the biological mechanisms of this budline's tolerance could be elucidated for developing more HLB tolerant germplasm via conventional breeding or biotechnological methods.