Global citrus production has been severely impacted by huanglongbing (HLB), a disease presumably caused by the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas). While there are not any commercial citrus cultivars currently available that have total resistance to this pathogen, several varieties show some degree of tolerance, including the LB8-9 ‘Sugar Belle’ mandarin. This cultivar was released by the UF/IFAS CREC Plant Improvement Team in 2009 and is known to be one of the most HLB tolerant varieties in HLB-endemic conditions when considering tree health. Fruit from this cultivar can be used for juicing or in the fresh market and with proper cultural care the trees consistently produce relatively high yields with typically an acceptable ratio of total soluble solids (TSS) to titratable acidity and value in pounds-solids per acre. Despite the improved tolerance to HLB in ‘Sugar Belle,’ many growers in Central and South Florida have had increased incidences of fruit disorders with this variety in the past several seasons. Fruit that are misshapen, have a poor peel color, or go soft on the tree are more common making this cultivar often undesirable for packing houses. The objective of this study is to determine if hedging the trees at different times (early summer, middle summer, or late summer), manually removing ~50% of the developing fruit in July (thinning), controlled release fertilizer applications, or oxytetracycline trunk injections will help mitigate some of the incidences of fruit disorders and increase overall fruit and juice quality at harvest. There were two sites used for this experiment (The Citrus Research and Education Center in Lake Alfred, FL, and Tamiami Citrus “Bee Branch Grove” in Avon Park, FL) and it was conducted over two seasons 2022-2024. Significant differences (p-value < 0.05) were discovered among the treatment groups in terms of TSS, titratable acidity, sugar:-acid ratio, pounds-solids per box, fruit size, yield, percent asymptomatic fruit, and peel rupture force. Despite evidence that some treatments may provide benefits to the grower, more research is needed to mitigate the soft fruit problem in ‘Sugar Belle’ mandarin.
