Plants frequently suffer from deficiencies of iron and other minor nutrients, such as manganese and zinc, elements essential to normal tree growth and development. Deficiencies can occur when 1 or more of these elements are depleted in the soil. Often, these minor nutrients are present in the soil but alkaline (pH 7.5 or higher) or wet soil conditions cause them to form compounds that cannot be used by the tree. An alkaline condition can result from overliming, from lime leached from cement or brick, or from calcium occurring naturally in the soil. Regions where soil is derived from limestone, and those with low rainfall, usually have alkaline soils.
To correct the iron deficiency, apply a chelated iron fertilizer to foliage and soil, or a fertilizer containing iron to the soil around the plants. Check the soil pH. (For information on pH, see pH.) Correct the pH of the soil by treating it with ferrous sulfate and watering it well, or by adding organic matter to the soil.
