Iron deficiency is a problem in areas with alkaline soils. Although the soil may contain plenty of iron, the high pH binds up the iron, keeping it from being absorbed by the plants. Known as iron chlorosis, this deficiency first appears as a yellowing of new growth leaves. Eventually, it spreads to older growth and the leaves may turn brown. The solution to iron chlorosis is chelated iron therapy. Chelated iron is available in liquid and granular form, but powdered iron chelate is the most common.
Purchase an iron chelated fertiliser. Look for iron in the Fe-DTPA, Fe-EDDHA or Fe-EDTA form. Read the label carefully to be sure that all the iron content is in one of these forms.
Apply chelated iron fertiliser at the drip line of trees and shrubs. Use approximately 85.1 to 142gr. of fertiliser for every 100 square feet of soil, sprinkling powder or pellets under the tree and out to approximately 1 foot beyond the foliage.
Apply a new dose of chelated iron fertiliser every month during the growing season.
Apply a foliar spray of iron chelate solution when symptoms of iron deficiency are severe. Mix the iron chelate with water according to the label directions.
Using a sprayer, apply the liquid iron chelate mixture to the leaves of the tree. Spray the tree thoroughly in the evening. Avoid spraying during hot weather when the spray dries quickly.
Using an iron foliar spray temporarily relieves the symptoms, but does not eliminate the problem. Follow up with iron chelate fertiliser applications.
Iron sprays and fertilisers will stain brick, concrete and rock. Avoid getting spray on these areas.