By Tripti Vashisth and Prudhvi Vulchi
To mitigate the effects of huanglongbing (HLB) on tree health and productivity, growers are encouraged to adopt proven horticultural practices. Based on recent field trials at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center (CREC), one effective approach combines frequent irrigation (FI), plant growth regulators (PGRs) and proper nutrient supplements.
Field trials began in 2021 with two irrigation treatments on 20-year-old Valencia trees: 1) control (every other day) and 2) FI applied daily in three 20-minute intervals. FI maintains more consistent soil moisture compared to conventional methods, which are applied every other day. This consistent moisture helps trees better manage water stress, particularly during low rainfall periods in spring and summer. FI improves root function and nutrient uptake, which leads to healthier trees.
After observing positive results with FI over three consecutive years, foliar PGR treatments and nutrients were added in 2024 to evaluate the effects of combining these strategies. The results showed that frequent irrigation, combined with PGRs and supplemental nutrients (FI + PNB), led to significant improvements in fruit size, yield and fruit drop reduction.
Trees treated with this combination exhibited larger fruit (62.21 millimeters compared to 58.55 millimeters in controls) and lower fruit drop percentages (29.74% in the FI + PNB treatment, compared to higher drop rates in other treatments). The highest canopy volume (24.55 m³) was observed in the FI treatment. Yield was higher in both the FI (47.5 pounds) and FI + PNB (47.15 pounds) treatments compared to the control (18.3 pounds). The FI + PNB treatment achieved the highest yield efficiency compared to the control. The addition of nutrients along with PGRs contributed to improved fruit quality.
Overall, combining frequent irrigation with PGRs and supplemental nutrients has proven to significantly enhance fruit size, yield, quality and yield efficiency while reducing fruit drop in HLB-affected trees.
Tripti Vashisth is associate center director and associate professor, and Prudhvi Vulchi is a graduate student pursuing a master’s degree, both at the UF/IFAS CREC in Lake Alfred.
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