Palm tree leaves naturally turn yellow, then brown as they age. Yellowing that occurs in patterns on the leaves or on a large number of leaves is not normal aging. Nutritional deficiencies are the most common culprit and can be treated easily. More rarely, yellowing could be the result of disease.
The most common nutritional deficiency in palms is potassium. Symptoms vary, but always appear on the oldest leaves first. Leaves may be mottled yellow or patterned brown at the tip, yellow in the middle and green at the base.
Magnesium deficiency affects older leaves first. The leaves turn yellow along the outside edge, while the center remains green.
Manganese deficiency first appears on older leaves. Wide bands of yellow streak the edges of the leaf, while the center portion remains green.
Nitrogen deficiency is more common among container raised palms. All leaves become a light green, then turn uniformly yellow.
Iron deficiency affects the newest leaves. The leaves emerge uniformly yellow.
Lethal Yellowing Disease
Lethal yellowing of palms destroyed coconut palms and other palms throughout the Caribbean and Florida. Yellowing begins at the bottom of the canopy and progresses to the top of the canopy. The condition is fatal.