Early Performance of Recently Released Rootstocks with Grapefruit, Navel Orange, and Mandarin Scions under Endemic Huanglongbing Conditions in Florida

Huanglongbing (HLB), which is believed to be caused by the phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas), has decimated Florida’s citrus production. Grapefruit production declined 75%, mandarin 78%, and sweet orange 52% due high sensitivity of commercial scions rootstocks disease. New combinations hybrid may provide better performance than current selections for fresh production, particularly in Indian River District. The objective this study was evaluate compare University Florida other recently released grafted with grapefruit, navel orange, measuring tree growth HLB tolerance. Three independent large-scale field trials were established September 2019 Fort Pierce, FL, USA. Trial 1 (T1) included 36 ‘Ray Ruby’ grapefruit as scion; Trials 2 3 (T2 T3, respectively) 30 ‘Glenn’ F-56-11 ‘UF-950’ scion, respectively. Tree canopy volume, trunk diameter, CLas titer, severity index, leaf nutrient concentrations evaluated during 2020 2021. Significant differences among rootstock-scion found each trial most assessed traits. In T2, UFR-15 consistently developed largest trees both years. larger on C-22, US-802. Similarly, US-802 US-942 generated trees. Overall, had optimum levels macro- micronutrients except calcium. infection visual index varied scion-rootstock combinations, especially first year when intensive flushing produced. Generally, grew vigorously WGFT+50-7 Willits inducing lowest symptoms all evaluations. Production fruit quality need determine suitability potential that can confer consistent economical biological advantages under scenario