Spray the foliage in the late spring or early summer when the leaves are expanding in size. Sprays are best applied in the early morning or in the evening when the air is calm and both the humidity and soil moisture are high. Foliar applications of iron materials give a quick but short recovery from chlorosis, but the effects will not last more than one season. Trunk Implantation . Introducing an iron salt into the trunk of an affected tree should control chlorosis for 2 to 4 years.
Treatment is quick, neat, and effective.
Recovery is often noted within 30 days. Three trunk implantation methods are available. Implanting ferric or ferrous citrate powder. Bore holes at an oblique angle, slanted downward, and 2 to 4 inches apart in a spiral around the tree beginning 1 to 3 feet above the soil line. Make a hole for each inch of trunk diameter.