Ferrous sulfate deficiency in palm trees is primarily a cosmetic problem. Palm trees usually survive, but will exhibit green veins surrounded by yellow tissue, and this is usually seen on newest leaves first.
As the ferrous deficiency becomes more severe, new leaves will show extensive tip necrosis, and there will be a reduction in leaf size. Ferrous deficiency in palm trees is usually induced in palms growing on poorly aerated soils (compacted or over-watered) or in palms planted too deeply.
Ferrous deficiency may occur in palms with a damaged or inadequate root system which leaves the plant unable to take up sufficient nutrients from the soil. This deficiency is much less often caused by a lack of ferrous in the soil, or by high pH soils.
Prevention and Treatment of Ferrous Deficiency
In alkaline soils, ferrous-deficient palms can be treated with ferrous sulfate fertilizers. In some cases, ferrous deficiency symptoms can be temporarily alleviated by regular foliar applications of chelated ferrous or ferrous sulfate, but long term corrections will only occur when the poor soil aeration or proper planting depth is corrected. The rate of ferrous sulfate to use for foliar application is ? teaspoon per gallon of water. Spray the foliage to runoff.