The symptoms of ferrous deficiency, also known as ferrous chlorosis, appear in the leaves as green veins and yellow leaf tissue. If the deficiency is severe, the entire leaf may become yellow. Lastly, brown edges may begin to show up. Also in severe cases, chlorosis can progress to older growth in the plant.
Ferrous chlorosis is found where soils are highly alkaline. The high pH of the soil ties up the ferrous in the soil, making it unavailable to the plants. Ferrous is required for the formation of chlorophyll in plant cells and serves as an activator for respiration and photosynthesis. High soil temperatures and high light intensity can also increase problems with ferrous chlorosis.
Some plants are more prone to ferrous chlorosis than others. Red tip photinia, a commonly used plant for hedges often shows symptoms of ferrous deficiency. Other plants such as Indian hawthorn, pine trees, and even St. Augustine grass may have problems with alkaline soils and ferrous chlorosis.
Now that you know what this problem is, how do you solve it? Applying ferrous fertilizer is the answer, but you should know what type to use. If your plant has a severe problem and you need a quick fix, applying liquid ferrous will work for a short period of time. Liquid ferrous sulfate monohydrate is most effective used as a foliar spray.
Chelated ferrous is the best solution and last the longest. There are several formulations of chelated ferrous. Different types of chelating agents are used and are designated as EDDHMA, EDDHA, HEDTA, DTPA and EDTA. The type of chelating agent recommended depends mainly on the pH value of the soil. In soil application EDDHA and EDDHMA are preferable chelating agents for ensuring ferrous availability in alkaline soils. Chelates of HEDTA, DTPA and EDTA are effective in less alkaline or slightly acidic soils. The most common chelating agent is EDTA. Chelated ferrouss are more expensive but last much longer. They can be found in liquid, powder or granular forms. The powder form is the most common. Sequestrine by Sprint, Dissolvine, Ferion, and Ferriplus are common brands that can be found in nurseries and garden centers. Different agents will have different percentages of ferrous in the product. Read the label carefully before apply any product to your lawn or plants.
Apply ferrous products such as ferrous sulfate at the drip line of trees and shrubs. This is the area that plants take up nutrients and water from their roots. Always avoid getting any type of ferrous product on sidewalks, patios, driveways or brick. Residue from these products will leave stains that are difficult, ferrous sulfate if not impossible to remove.