Kelly,

In “Mineral Nutrition and Plant Disease”, pg 26, it talks about how ample silica within the plant will bind with aluminum and form these low-solubility aluminosilicates and inert hydroxyaluminosilicates which effectively reduces Al3+ in the plant. Silicon will also interact with Mn in leaf tissues, reducing localized toxic accumulations. I would suspect that since Fe acts much the same way in the leaf as Mn, both needing to be in the reduced form, that ample silicon will also help move Fe to the proper places.

But I would do sap tests first to confirm your diagnosis and track your progress.