From Symptoms To Solutions: How Iodine Can Alleviate the Effects of Citrus Greening (HLB)
Hualongbing (HLB), commonly called citrus greening disease, is a serious bacterial infection that is transmitted by the Asian citrus psyllid. The bacteria causes blockages in the vascular system of the trees, affecting nutrient distribution. It has had a negative impact on fresh and processed fruit in citrus operations around the world, as it leads to reduced fruit yield, reduced fruit quality and ultimately, tree death.
Research leaves no doubt that potassium nitrate is the preferred K-source to improve tree health, yield, and fruit quality. A balanced nutritional program, combining foliar, dry and fertigation applications of potassium nitrate can help the tree mitigate the effects of HLB.*
*https://sqmnutrition.com/en/essays/potassium-nitrate-sprays-in-citrus-doubled-the-yield-of-trees/
Iodine is beneficial for root growth and resilience to stress in citrus
Two trials conducted on Florida citrus trees demonstrated how iodine can boost tree resilience. Observations on tree growth in a potted trial with Valencia trees grafted on sour orange root stock demonstrated that iodine absorbed/stored in the roots will lead to better root growth and increased nutrient uptake.
The control trees received the same fertilizer solution, including the same amount of potassium nitrate without iodine.
49 mg/tree of iodine was applied with 49 g/tree of Ultrasoline K Plus as component of a complete fertilizer solution, split in 24 application moments during 6 months of tree propagation in pots with a sandy soil.
Observations on yield in a commercially managed grove, demonstrated that Ultrasoline helped to maintain soluble sugar content in fruits of HLB-infected trees.
2021 - 2023 Florida Research for Agricultural Sustainability, Vero Beach, Florida, USA Valencia Citrus Trial Results (HLB infected trees)
*SL 253, Nutrition of Florida Citrus Trees, 3rd Ed. Chapter 8, Fertilizer Rates, Application Frequency, & Timing for bearing citrus trees, Table 5, p. 63. published March 2020 by the Univ. of Fla./IFAS Extension.
Trial details
• Trees: 4 years old at the start of the trial.
• Setup: 12 single-tree replicates.
• Application: Ultrasoline K Plus at 35 lbs/a, applied by drench or foliar spray - in each of 12 monthly applications.
• Control: Grower standard fertility program without additional potassium nitrate.
Challenges
• Superficial rooting zone over hard bedrock.
• Damage from hurricanes.
• Excess precipitation alternating with heat.
• Various pests and diseases, including HLB (citrus greening).
Results
Trees treated with Ultrasoline K Plus showed a better resilience to abiotic and biotic stresses. Results from a 2 year trial showed yield increase, higher brix, higher juice content and an increase in pounds solids by 11%.
