Combining Horticultural Practices to Improve Yield of Huanglongbing-affected Citrus
Posted August 2025
Researchers: Tripti Vashisth
Contact: Tripti Vashisth, UF/IFAS CREC tvashisth@ufl.edu
Summary:
Water deficit has a strong impact on huanglongbing (HLB) affected citrus because of the severe damage to the root system the disease causes. Recent research has shown that more frequent daily irrigation (FI) during the dry spring period has a positive effect on final yield and canopy density compared to a standard irrigation program (SI) of two hours every other day. The positive impact that plant growth regulators (PGRs) have on HLB-affected citrus has also been shown in many other field trials, specifically the impact of the use of gibberellic acid (GA) for the improvement of canopy health. Using an already existing trial testing out FI, PGRs in combination with foliar nutrients were applied to a set of trees receiving the FI treatment. The treatment contained cytokinin and calcium nitrate in the spring followed by GA, potassium, and micronutrients. Sprays were applied every 45 days from May until October. After one year of applications, the FI+PGR had significantly higher yield with an average of 48 pounds per tree which was significantly higher than the SI and FI treatments. FI+PGR also had significantly less fruit drop than SI and FI by an average of 30% as shown by the blue dots on the graph. Fruit quality was also trending higher in the FI+PGR treatment, probably due to the nutrients, which addresses some concern over PGRs reducing fruit quality. Combining enhanced horticultural practices, such as frequent irrigation and PGRs, can improve the yield and reduce fruit drop in HLB-affected citrus.
Take Home Message:
- Frequent irrigation + PGRs + nutrition can improve the yield and fruit quality of HLB-affected sweet oranges.
- The use of PGRs, when applied at the right time and rate, can increase yield and reduce fruit drop.
- Foliar nutrients such as potassium, alongside PGRs may contribute to improved fruit production.
