The effect of the ionization state of iron and citric acid on the health of HLB-infected trees.

The effect of the ionization state of iron and citric acid on the health of HLB-infected trees.

Report Date: 11/15/2019
Project: 18-050C   Year: 2019
Category: Horticultural & Management
Author: Randall Niedz
Sponsor: Citrus Research and Development Foundation

Objective 1 – Ongoing.
Objective 2 – Determine the phytotoxic levels of Fe + organic acid solutions on citrus.

Preliminary range experiments were started using F11 to determine the concentration where leaf burn occurs. F11 is the Japanese Fe + citric acid product developed from the patent. In discussions with the Japanese inventors (who visited Florida to see the project), we just learned that another product, F11-C, is the product that was developed from this patent specifically for citrus. Therefore, we have modified all experiments, greenhouse and field, to use F11-C rather than F11. Aichi Steel, the manufacturer of F11 and F11-C, have provided us with all the product required for the project.

Objective 3 – Determine the effect of Fe2+ + organic acid solutions on HLB titer using a rapid greenhouse, HLB-infected citron, rooted shoot bud assay.

Being modified. Originally, we planned on using HLB-infected citron bud cuttings because they show clear HLB symptoms, but are still able to grow. This is unlike HLB-infected grapefruit that can barely be kept alive. However, in our experiments to characterize the “citron system” we have been able to detect very little growth differences between HLB-infected vs healthy citron plants. This means that treatment effects on HLB-infected plants cannot be determined, only the general effects on plant growth. We are working on another system based on very young sweet orange plants and psyllid inoculation where the preliminary experiment looked very promising. The HLB effect was very strong, the requirement for a good system to test treatments. The validation experiment is now being rerun at a larger scale. If it validates, then we will use this system on the objective 3 (and objectives 4 and 5) experiments where it should work quite well.

Objective 4 – See objective 3 discussion.
Objective 5 – See objective 3 discussion.

Objectives 6 and 7 – These are the field tests on mature and young trees. The trees have been planted, baseline ground and aerial data taken, and treatments initiated.

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