What Causes a Queen Palm Tree to Turn Yellow?
Growing up to 50 feet tall, the queen palm (Syagrus romanzoffiana) is a regal evergreen that showcases a smooth gray trunk topped with glossy green fronds that may be up to 10 feet long. A queen palm with yellowing leaves probably suffers from a nutrient deficiency, though pests may also be to blame. Fortunately, queen palm is resistant to Lethal Yellowing Disease, a serious palm disease that also causes yellow fronds.
A queen palm suffering from a manganese deficiency will often produce new leaves that are deformed or bronze or yellow in color. Manganese foliar spray applied directly to the fronds will lead to a faster return to green coloring but are less effective in the long run than soil applications. Make a foliar spray solution by mixing 3 pounds of manganese sulfate per 100 gallons of water. The University of Florida notes that the amount of manganese sulfate needed for a soil application may be anywhere from 8 ounces to 8 pounds, depending on the size of the palm.
Iron deficiency causes new leaves to yellow. In severe cases, frond tips may yellow and the whole palm may be stunted. Iron deficiency is much more common in container-grown palms than palms grown in the garden, according to the University of Florida Extension. It is often caused by poorly draining soils or from planting the palm too deeply, factors that prevent the palm from absorbing iron. Size permitting, replant the palm in a well-aerated soil at whatever depth it was when you first purchased it. You can also fertilize the palm with a chelated iron fertilizer, as per label recommendations.
Queen palm is susceptible to the palm leaf skeletonizer, a caterpillar that eats away at fronds until just the veins are left, giving the fronds a skeleton-like appearance. An early infestation may resemble a nutrient deficiency, as the leaves will look yellow or bronze. You can wash larvae off container plants with a sponge and taller palms with a high-powered hose. It is also possible that nothing is wrong with your palm: It is normal for older queen palm fronds to die and remain on the tree.
Queen palm requires well-draining, acidic soil. Planting the queen palm in alkaline soil is a surefire recipe for mineral deficiencies and poor growth. A sickly palm that is stressed due to poor cultural conditions is more likely to attract diseases and pests than a healthy, happy palm. Queen palm is hardy in U.S. Department of Agriculture plant hardiness zones 9B through 11, where it requires full or partial sunlight and regular irrigation.