Have you tried an iron foliar or an all purpose foliar (that also has iron) such as this which is available in my Home Depots at least. All below are chelated minerals and iron
http://www.southernag.com/docs/labels_msds/chcitr.pdf
Iron foliar http://www.irrigation-mart.com/Documents/Chemicals/ironchelatedp.pdf (they have one chelated iron drench for high ph soil and one for low) (but all can be used as foliars) (think chelates!!! whether foliar or into the soil)
I’ve been using ferrous sulphate to drop the soil pH. I may have to try the chelated products again.