Q. Quite a few trees on my property are chlorotic. Is there a particular fertilizer I can use to eliminate this problem?
A. Chlorosis, the yellowing of leaves with the tissue near the veins remaining bright green, can be caused by a deficiency of iron or manganese in the soil. It also can be caused by alkaline, compacted or waterlogged soils, pollution and other environmental causes. The plants in our area most susceptible to iron deficiency are the white and pin oaks, hollies, certain azaleas and rhododendrons, black and white pines and magnolias. The plants susceptible to manganese deficiency are birch, flowering cherry, dogwoods, maples (especially red and sugar) and the sargent crab.
First, take a soil test of the area and follow the recommendations included. Soil-testing agencies are also able to perform foliar analysis to identify deficiencies. It is important to know which micronutrients are missing before adding any amendments to the soil. However, the addition of organic matter as well as granulated sulfur can often be helpful in cases of chlorosis.