Progress on objectives 1, 2, 6, and 8 were made as follows:
Objective 1 – The ratio effect of Fe2+ and citric acid concentration and proportion on hydroxyl radical production and stability will be quantified and validated by response surface methods with accompanying mathematical models and ANOVA.
An assay to quantify hydroxyl radical production via ferrous iron induced Fenton reaction was setup and calibrated (i.e., standard curves). The hydroxyl radicals produced by the Fenton reaction degrade the dye methylene blue, and is measured by spectrophotometry. This assay is required to determine the Fe2+/citric acid ratio effects.
Objective 2 – Phytotoxic effects of Fe2+ and citric acid concentration and proportion will be quantified and validated by response surface methods with accompanying mathematical models and ANOVA.
Citron plants for this experiment were established from bud cuttings.
Objective 6 and 8 (Note: there is no objective 7) – Effects of Fe2+ and citric acid treatment on HLB status and horticultural measures of young newly planted trees AND mature HLB-infected field trees are in progress. Prior to treatment applications, the caliper and height for each of the newly trees was measured. Tree condition for the mature trees was visually determined by disease indexing (DI) according to the methods of T. R. Gottwald, B. Aubert and Z. Xue-Yuan. Trees with a similar DI were selected, flagged, randomized and mapped for treatment.
Aerial images were acquired (drone) for the young and mature field planting. Images will provide canopy size, density, and shape data. This data, in combination with ground data, will form a baseline measure for treatment comparisons over time.