Oil palms (Elaeis guineensis) are native to tropical areas of Africa. In the wild, these trees can grow up to 80 feet tall, but when cultivated, they typically only reach a maximum height of 30 feet. Sometimes called queen palms, oil palms are desirable for the oil contained in their drupes. The process of extracting the oil is long and arduous, but the end result is a profitable export that is used in many food products, including margarine and ice cream. Diseases can be devastating for oil palm plantations.
Basal Stem Rot
Basal stem rot is a lethal disease for palm trees and the most serious of all diseases affecting the oil palm, according to M.L. Elliott, a plant pathologist with the University of Florida. Basal stem rot, which is also called Ganoderma butt rot, is caused by the Gandoderma fungus. The fungus attacks the bottom of the tree and works its way upward, killing the tissue inside of the trunk. The tree loses the ability to absorb nutrients, causing the palms at the crown of the tree to shrivel, turn yellow or fail to emerge at all. Unfortunately, by the time these symptoms appear, the disease has already killed lower 5 feet or so of the tree. As the fungus climbs up the tree, it produces growths that protrude from the infected plant. These conks house the developing spores of the fungus. One gust of wind can blow the spores onto nearby oil palm trees. According to Elliot, no effective way to prevent, control or cure this disease exists.
Red Ring Disease
A parasitic, microscopic worm called a nematode causes red ring disease. These pests can invade an oil palm through a wound or on the bodies of creeping insects-- in particular, the palm weevil. Red ring disease is so named for the red ring it leaves on crosscuts of infected trees. External symptoms of the disease include a failure to thrive and severely deformed leaves and crowns. This disease can kill young trees in as little as two months. The most effective way to combat this disease, according to A.S. Brammer and W.T. Crow, entomologists with the University of Florida, is to remove and destroy infected trees (usually by burning) to keep the nematodes from spreading. Spray the trees with an insecticide before removing them to kill any weevils that might escape to a new tree.
Crown disease is one of the milder diseases that oil palms face. While it is disfiguring, it usually does not kill the tree. Instead, it reduces the oil production during the course of the disease, which runs between three and four years. Symptoms include malformed palm spears, or fronds covered with fungal rot. Crown disease is most often the result of poor environmental conditions, including damage to the roots during planting, a lack of nutrients in the soil or a general weakening of the tree from an insect infestation. With time and care, most trees recover on their own.