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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Research Project #435920

Research Project: The Effect of the Ionization State of Iron and Citric Acid on the Health of HLB-infected Trees

Location: Subtropical Insects and Horticulture Research

Project Number: 6034-21000-018-16-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Nov 1, 2018
End Date: Oct 31, 2021

Objective:
The overall objective is to determine if the use of iron Fe2+ and an organic acid will cure or substantially reduce Candidatus Liberibacter asiaticus titer in citrus trees with Huanglongbing. 1) Determine the effect of the ratio and concentration of iron Fe2+ + organic acid on hydroxyl radical production and stability. 2) Determine the phytotoxic levels of iron Fe2+ + organic acid solutions on citrus. 3) Determine the effect of iron Fe2+ + organic acid solutions on huanglongbing (HLB)titer using a rapid greenhouse, huanglonbing (HLB)-infected citron, rooted shoot bud assay. 4) Determine the effect of iron Fe2+ + organic acid solutions on protecting healthy citrus from becoming infected by huanglongbing (HLB)+ psyllids. 5) Determine the main and interactive effects of supplemental iron, manganese, boron, zinc, and copper using a rapid greenhouse, huanglongbing (HLB)-infected citron, rooted shoot bud assay. Iron delivered as Fe2+ + organic acid. 6) Determine the effect of iron Fe2+ + organic acid solutions on mature huanglongbing (HLB)-infected field trees. 7) Determine the effect of iron Fe2+ + organic acid solutions on nearly planted (<2 years old) field trees.

Approach:
Laboratory, greenhouse, and field experiments will be conducted. Laboratory experiments will determine the stability of the iron Fe(2+) ion with various proportions and concentrations of citric acid, the production of hydroxyl radicals by the Fenton reaction, and the proportion of Fe(2+) iron with various proportions and concentrations of citric acid and pH. Greenhouse experiments will use a model system of huanglongbing (HLB)-infected citron cuttings to evaluate the effect of various proportions and concentrations of iron Fe(2+) and citric acid on huanglongbing (HLB) titer and plant growth, as well as various types of applications (foliar, drench, foliar + drench). Field experiments will determine the effect of iron Fe(2+) + citric acid applied as foliar, drench, or foliar + drench on the health and HLB-titer of mature and young citrus trees HLB-infected citron cuttings to evaluate the effect of various proportions and concentrations of iron Fe(2+) and citric acid.