Acidify the soil. Best results have often come with a mix of a fast acidifier, a slow acidifier, and organic matter. Repeat as necessary . Apply a chelate as a soil drench if one micronutrient is involved. Repeat as necessary.
Tree injection works well, but requires multiple and repeated wounding.
Spraying is ineffective, because crown coverage is difficult and marginal leaf scorch is easy. Koenig, Rich, and Mike Kuhns. Control of Iron Chlorosis in Ornamental and Crop Plants. Utah State University Extension. For other information, advice and help on this topic, call offices of your State Urban Forestry Coordinator or University Extension service, or visit urban forestry web sites .