Prized for the coconuts they produce, the shade they provide, their beauty and the tropical atmosphere they help create, a healthy coconut palm tree is a valuable plant. Unfortunately, they are easily killed or damaged by several diseases, and only preventive measures or early treatment can save them. Most coconut palm tree diseases are caused by fungus and bacteria and are spread from tree to tree by the wind, insects and rodents.
Lethal Yellowing, or LY as it is commonly called, is one of the most common diseases of the coconut palm tree and has been especially devastating to trees in southern Florida. Early signs of Lethal Yellowing include loss of immature fruit and discoloration of lower fronds. As it progresses, all of the fronds begin to turn yellow and drop off, until eventually the entire crown of the coconut tree falls off. This process usually takes about six months, but according to the University of Florida Extension, each species of coconut palm is affected differently. University of Florida researchers also point out that trees with more than 25 percent yellow fronds should be considered infected and the entire tree should be removed. Antibiotic injections are sometimes effective in stopping Lethal Yellowing.
Because it kills the bud, which is the source of new growth, once it sets in, bud rot is impossible to stop. The first signs are the death of the spear leaf, or newest unopened leaf and the subsequent withering of other new leaves or fronds. While lethal yellowing starts from the bottom and works its way up, bud rot symptoms start at the top and work their way down. It also appears as dark brown and gray spots on fronds, or browning at the base of the fronds. Bud rot usually results in a foul odor coming from the bud as well. Several types of fungus and bacteria are believed to cause bud rot, and it commonly occurs after coconut palm trees have been damaged by cold weather, when their defenses are down.
Thielaviopsis Trunk Rot
Named after fungus which causes it, Thielaviopsis paradoxa, coconut palm trees affected by Thielaviopsis Trunk Rot die suddenly and often without warning. The fungus gains entry to the tree through wounds on the trunk. Portions of the trunk begin to rot, and the tree either collapses or the crown falls off, depending on the location of the rot. Treatment is successful only if the infection is recognized early. The infected area must be removed and the coconut palm sprayed with an appropriate antifungal. If treatment is not possible, the tree should be removed and destroyed immediately to prevent the disease from spreading to other trees.