By Olivia Techoueyres
Hawai`i’s tropical image is often portrayed by its beautiful white sand beaches and magnificent swaying coconut trees. These trees are also a symbol of the visitor industry and are used widely for landscaping parks, roadways, business districts, hotels, golf courses, scenic vistas, and residences. Besides their beauty, “the tree of life” provided a valuable source of food and building materials for the Hawaiians and other islanders. Unfortunately, the future of coconut trees in the islands is bleak, because of a devastating disease that is killing them at an alarming rate.
This disease, known as “coconut heart rot”, is caused by the fungus Phytophthora katsurae. The pathogen was first identified in the 1970 by the University of Hawai`i (UH) on Kaua`i. The disease started on the windward side of the Islands with the loss of few trees. Nobody got alarmed because it seemed to spread slowly and was attributed to the wetness of the location. However in the last few years, coconut palms have died in great numbers on the windward side despite the unusual droughts.
On Maui, approximately 20 percent of the coconut trees have died. Scattered outbreaks are now beginning to occur in the drier areas of central, south and west Maui. The disease has also become an epidemic in Kaua`i, O`ahu and the Big Island.
The dead palm shown on the cover, a victim of the disease, is located at the North Kihei Road entrance to Kihei. Infected trees have also been found in Kahului, Wailuku, Kihei, Wailea, Makena, Lahaina, Ka`anapali, Napili, Kapalua. Experts are realizing that the disease is now on the leeward side of the Islands, and the daily irrigation combined with the strong heat of the day will help the fungus thrive.
Although no one really knows how this fungus got to Hawai`i, most scientists believe that it is spread by strong windblown rains, through insects, birds, and mice, or by pruning and planting infected trees. The infection is carried by a given agent (rain, insects, etc.) to the top of a nearby healthy tree where the fungus then moves down into the heart of the palm, producing a rot that slowly destroys the growing shoot and kills the plant.
The first visible symptom of coconut heart rot is the death of the young center leaf, which turns brown and falls over. As the rot advances, other remaining fronds slowly droop and die.
Eventually, the top of the tree falls off… leaving what looks like an abandoned pole. Another possible symptom is the appearance of a stem end rot on young developing nuts, which causes them to fall prematurely. The dreadful thing about this disease is that once external symptoms are displayed, the heart of the palm is already rotten and the tree can no longer be saved. Furthermore, if the infected tree is not immediately removed and properly disposed, the fungus can easily spread to neighboring palms.
As precaution, experts recommend the following: never prune healthy trees if you suspect your tools (pruners, knives, etc.), equipment (chain saws, ladders or lifts, truck beds, etc.), or any other materials (hands, gloves, shoes, clothing, etc.) may have been contaminated with the fungus. Thoroughly wash, clean, or disinfect these items with a 20% solution of Clorox, or 70% Isopropyl rubbing alcohol to avoid spreading the disease. Once a dead tree has been cut down, it should be immediately buried, burned (fire permit may be required), or taken to the landfill. When hauling a diseased tree, it must be properly wrapped or covered to prevent any infected tissues or insects from spreading along the roadway, thereby causing new outbreaks in other locations.
Because coconut trees are very slow growing (about one foot per year), it is estimated that a highly prized 20 foot tree is about 20 years old. At $50 per foot of trunk, plus transportation, equipment (e.g., backhoe, crane), and labor charges, the cost to remove and replace a dead tree with another of similar stature could be as much as $3,000 or more. In some situations, accessibility may be a problem and replacing it may be impractical. For some businesses, it may create a huge disturbance to its customers and guests. Furthermore, trees of this size are in short supply or may be unavailable from many nurseries.
Preliminary research conducted on Kaua`i by the university showed that disease protection was being achieved by injection into the trunk of coconut trees. Unfortunately, this experiment was destroyed by Hurricane Iniki before the final results could be taken.
In an effort to save Hawai`i’s coconut trees, the Hawai`i Farm Bureau Federation, Department of Agriculture, University of Hawai`i, Maui Association of Landscape Professionals, Hawai`i Organic Farmers Association, several Hotel Associations, and the County of Maui are supporting a funding request to the State Legislature to enable UH to finalize its research on this disease.
In the meantime, an education and injection program has been put together by Hawai`i Coconut Protectors to help protect the palms from contracting the disease. Seminars, Presentations to both the Landscaping and Tourism Industry have been held. Many private owners, hotels and resorts, golf courses, restaurants,condos have already protected their trees. The collaboration and support of residents is needed to stop the further spread of the disease. Because of the large population of coconut palms, as well as the fact that they do not show any outside noticeable symptoms until they are dead and usually cut down, the disease has been allowed to spread and remain unnoticed to the untrained eye. The reality is that we are starting to see landscaping like that of picture below taken on the windward side of Maui. If we wait any longer, we will not be able to save our island heritage…
Information about the coconut heart rot may be obtained by visiting www.coconutprotectors.com or calling (808) 573-1850.
By Olivia Techoueyres