Effects of fertilization and pruning on canopy leaf number and potassium deficiency symptom severity in Sabal palmetto

Palms 57 (2): 84-88

Potassium deficiency is the most common nutrient deficiency on landscape palms in the southeastern United States. Early symptoms appear as translucent yelloworange and/or necrotic spotting on the oldest leaves. As the deficiency progresses, leaflet tip necrosis and frizzling develop, which eventually results in premature loss of the leaf. Deficiency symptoms are most severe on the oldest leaves because potassium is mobile within the palm. Under conditions of deficiency, the palm is able to extract potassium from the oldest leaves and translocate it to the newly developing leaves, allowing growth to continue in the absence of sufficient potassium in the soil. Depending on the species and potassium deficiency severity, leaf death occurs from one to three months after necrosis is first observed on a particular leaf. In contrast, natural senescence of healthy, non-potassium-deficient older leaves occurs rapidly, with the oldest leaf being completely green one day, uniformly orange-brown the next day, and completely necrotic by the third or fourth day.