Therapeutic Effects of
CitruSaver on HLB-Affected Trees
University of Florida Institute of Food and Agricultural Sciences · Citrus Research and Education Center, Lake Alfred, FL · Davie Kadyampakeni, Associate Professor
+43%
lb Solids/Tree · Fort Meade CS1
+109%
lb Solids/Tree · 4-Year Micro Jet
+35%
Canopy Volume · Fort Meade CS1
15.7
Brix/Acid Ratio · 4-Year Block
Initial Results Across Florida & Texas Groves
This report covers progress made across multiple commercial citrus grove sites in Florida and Texas from Fall 2024 to Spring 2025. The project focuses on Valencia, Hamlin, and Grapefruit varieties — assessing the therapeutic effects of CitruSaver biostimulants and beneficial microbes on HLB-affected trees.
Both commercial Valencia field-trial groves in Florida received two years of prior OTC (oxytetracycline) trunk injections before this study began — providing a real-world comparison context. Texas sites were not pre-treated with OTC.
The Fort Meade micro jet-irrigated Valencia block — 10 acres (~1,300 trees) — has received continuous CitruSaver treatments for four years, serving as the study's most compelling long-term data point.
Study Scope at a Glance
Treatments Tested
CS1 (CitruSaver 1) · CS2 (CitruSaver 2) · CS2+BM (CitruSaver 2 + Beneficial Microbes) · BM only · Untreated Control · Micro jet irrigation block
Beneficial Microbes Applied
Azotobacter chroococcum and Pseudomonas protegens — known to promote plant growth, enhance nitrogen fixation, improve phosphorus cycling, and suppress pathogens
Application Schedule
9 weeks total · 3 root zone applications + 1 foliar application · 2-week intervals · Valencia FL blocks treated first, Texas and Hamlin FL initiated Spring 2025
Data Collected
Fruit yield (kg/tree, lb solids) · Juice quality (°Brix, TA, Brix/acid RI, juice color) · Canopy volume (m³) · Fruit drop counts · CLas titer (qPCR) · Soil & tissue baseline samples
Statistical Method
Mean separation via Tukey's Honest Significant Difference (HSD) at p ≤ 0.05 across all reported outcomes
CS1 Outperformed Control at Both Sites
CS1 was the only treatment to consistently outperform the untreated control at both Fort Meade and Wauchula. The 4-year continuously treated micro jet block delivered the most dramatic long-term yield result.
Fort Meade Valencia — Spring 2025 Harvest
Harvest date: April 29, 2025 · ~3 months after first CitruSaver application
| Treatment | Fruit Yield/Tree (LBS) | lb Solids/Tree | vs Control |
|---|---|---|---|
| Micro Jet (4 yrs) | 14.26 | 0.78 | +109% |
| CitruSaver 1 (CS1) | 8.84 | 0.53 | +43% |
| CitruSaver 2 (CS2) | 7.70 | 0.44 | +19% |
| Microbes (BM) | 5.13 | 0.30 | −19% |
| CS2 + Microbes | 5.06 | 0.29 | −22% |
| Control (untreated) | 6.49 | 0.37 | Baseline |
Note: Lower overall yields reflect late picking due to juice plant scheduling delay, not treatment performance.
Wauchula Valencia — Spring 2025 Harvest
Harvest date: March 26, 2025 · ~2 months after first CitruSaver application
| Treatment | Fruit Yield/Tree (LBS) | lb Solids/Tree | vs Control |
|---|---|---|---|
| CitruSaver 1 (CS1) | 107.28 | 6.63 | +20% |
| Microbes (BM) | 107.08 | 6.60 | +20% |
| CS2 + Microbes | 100.63 | 6.16 | +11% |
| CitruSaver 2 (CS2) | 79.93 | 4.85 | −12% |
| Control (untreated) | 90.35 | 5.52 | Baseline |
Reference: Florida average Valencia fruit yield was 38 kg/tree for groves harvested during the same period.
CS1 Consistently Grew Larger, Healthier Canopies
Canopy volume (m³) was measured in both Wauchula and Fort Meade approximately 4–5 months after the first CitruSaver treatment application. CS1 showed the highest canopy volumes at both sites.
Wauchula Valencia · June 6, 2025
~4 Months After Treatment Start
+10%
CS1 vs Control
Fort Meade Valencia · June 20, 2025
~5 Months After Treatment Start
+35%
CS1 vs Control
Key Canopy Finding
CS1 consistently enhanced canopy volume compared to the Control at both locations. Fort Meade CS1-treated trees showed a 35% larger canopy volume than control trees — a direct indicator of improved above-ground vigor and photosynthetic potential. Treated trees also exhibited noticeably less branch dieback than control trees at both Fort Meade and Wauchula.
More Yield — Without Compromising Quality
All fruit quality parameters — sugar content, titratable acidity, ripening index, and juice color — were statistically identical across all treatments. Yield gains were purely additive.
~9–10°
Soluble Solids (°Brix)
No significant difference across any treatment group at Fort Meade or Wauchula.
Stable
Titratable Acidity
Consistent acidity levels across all treatments. No measurable increase or decrease from treatment.
15.7
Brix/Acid Ratio (4-yr)
Highest ratio at Fort Meade 4-year micro jet block — all treatments exceeded control Brix ratio.
Uniform
Juice Color
Juice color (scale ~37) statistically identical across all treatments — premium market appearance preserved.
Average Brix/Acid Ratio — Fort Meade (All Treatments)
All treatments exceeded the control. 4-year micro jet block produced the highest ratio (15.7) — most favorable sugar-to-acid balance.
Fall 2024 – Spring 2025
qPCR Analysis — CLas Titer Across All Sites
All leaf tissue samples were analyzed using quantitative polymerase chain reaction (qPCR) to measure Candidatus Liberibacter asiaticus (CLas) titer — the causal agent of HLB. CLas load was measured for all treatment groups at all sites.
How to read the data: Higher cycle threshold (Ct) values indicate lower bacterial load (less disease). Lower Ct values indicate more advanced HLB infection. Texas sites showed higher Ct values (lower bacterial load) than Florida — reflecting less advanced disease progression.
Higher Ct Value
= Lower bacterial load = Less advanced HLB infection = Better tree health
Lower Ct Value
= Higher bacterial load = More advanced HLB infection = Greater disease burden
Florida Sites (Wauchula + Fort Meade)
Ct ~25
Higher disease burden — Florida groves had pre-existing OTC antibiotic trunk injection history. Ct values clustered around 25 across all treatments, indicating moderate-to-high HLB infection levels.
Texas Sites (Valencia + Grapefruit)
Ct ~33–38
Lower disease burden — Texas sites had no prior OTC treatment. Higher Ct values reflect lower CLas bacterial load across all treatment groups, indicating less advanced HLB disease progression.
qPCR analysis was completed for all experimental blocks in both states. This baseline CLas titer data will be used to track disease suppression or progression across treatment groups in future reporting periods.
Real-World Conditions Tracked Transparently
Localized Fruit Drop
Unusual fruit drop was observed in certain Valencia trees in Florida, potentially linked to soil moisture fluctuations or tree stress. Cases are being monitored closely in subsequent phases.
Grower Irrigation Variability
Inconsistent irrigation by some growers — particularly under-watering during dry periods — affected uniformity of treatment impacts. Continued grower engagement and education will be critical going forward.
Gummosis in Texas Grapefruit
Gummosis symptoms appeared in some Texas grapefruit trees, raising concerns about pathogen interference. Monitoring and mitigation strategies have been flagged for the next project phase.
Significant Initial Progress. Encouraging Results.
CitruSaver 1 treated trees yielded 43% higher total pound solids per tree at Fort Meade and 20% higher at Wauchula compared to control trees. The Fort Meade 4-year micro jet block yielded 109% more pound solids — a compelling long-term signal. Treated trees exhibited greater canopy vigor, new flush growth, and noticeably less branch dieback than control trees.
Results should be considered preliminary due to early-stage treatment durations and site variability. Continued research through 2025–2026 will validate these trends. Full report: Davie Kadyampakeni, UF/IFAS Citrus REC, Lake Alfred, FL.
Source: Assessing therapeutic effects of CitruSaver on the productivity and health of HLB-affected citrus trees Davie Kadyampakeni, UF/IFAS Citrus REC, Lake Alfred, Florida