Trees, Shrubs, and Vines: Iron Deficiency

Problem
Leaves turn pale green or yellow.

Analysis
Plants frequently suffer from deficiencies of iron and other minor nutrients, such as manganese and zinc, elements essential to normal plant 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 above 7.0) or wet soil conditions cause them to form compounds that cannot be used by the plant. An alkaline condition can result from overliming, or from lime leached from cement or brick. Regions where soil is derived from limestone, and those with low rainfall, usually have alkaline soils.

Solution
To correct the iron deficiency, spray the foliage with a chelated iron fertilizer, and apply it to the soil around the plant. Apply aluminum sulfate or a lime-sulfur spray to correct the pH. (For more information about pH, see pH.) Treating the soil with ferrous sulfate may also correct the pH of the soil. Place it in holes (6 inches deep for shrubs and 2 feet deep for trees) around the plant under the branches, and water it in well. Maintain an acid pH by fertilizing with an acid-reaction fertilizer. When planting in an area with alkaline soil, add a handful of soil sulfur, or add enough peat moss to make up 50 percent of the amended soil and mix it in well.