Gov’t Working to Combat Lethal Yellowing Disease

The Ministry of Agriculture and Fisheries and the Coconut Industry Board (CIB) are using everything at their disposal, including research and replanting, to combat the lethal yellowing disease, which is threatening the livelihood of some 8,000 coconut farmers in Jamaica.

Currently, these farmers are cultivating 3.3 million coconut palms on 13,500 hectares of land, producing approximately 97.4 million nuts for the industry, which earned $1 billion last year.

The Ministry, over the years, has embarked on various activities to eradicate the disease. “We have a research department actively looking at all aspects of the disease,” says Dr. Wayne Myrie, Plant Pathologist and Molecular Biologist at the CIB.

“We are looking at the pathogen and the environmental factors affecting the spread of the disease, as well as the vector that transmits the disease, moving it from one plant to the next.  In addition, we are looking at the coconut palm itself,  its susceptibility and disease resistant capabilities and agronomical practices that should be carried out to make the palm more resistant to the disease or help the palm to resist the disease, and we are also looking at replanting,”  he informs.

In addition, a plant variety that is resistant to the disease has been developed, which is being made available to farmers on a limited basis, as research and experimentation are ongoing.

While the research continues, the Ministry is encouraging farmers to employ the “Black Approach,” first practised by farmer Michael Black of Nuts River farm in St. Thomas, as means of containing the disease.

The method involves replacing infected trees with healthy ones.  And so farmers, at the first sign of the disease, are encouraged to immediately remove the infected tree and plant another one in its place.

Because the pathogen of lethal yellowing disease is found in the sap of the coconut palm, planting new trees in the soils from which infected trees were removed, does not affect new trees.

Farmers are also advised to practise proper nutrition for the plants and good weed control.  “Proper nutrition means that bearing trees require adequate nutrition to support the nuts it will bear every month or throughout the year.  We recommend a fertilizer that is high in potassium, to support the tree’s production,” Dr. Myrie states. Lethal yellowing is a devastating disease that affects coconuts and about 35 other palm species.  The disease is caused by a phytoplasma, which is a bacterium  found in the sap of the coconut palm.  It multiplies in the sap and through the multiplication and the living of this organism in the sap, it kills the coconut plant.   

Within this region, the disease was first discovered in the Caymans Islands in 1834, and was found in Jamaica 50 years later, in 1884.  It became a real threat to Jamaica after 1961, when it appeared in the Buff Bay area of Portland, and became even more significant in the 1970s, when some 10 million “Jamaica Talls” were destroyed.  

“The last major outbreak was in the late 1990s when over one million coconut palms were destroyed and the remnants of this outbreak are still being felt,” says Dr. Myrie.

Symptoms of lethal yellowing disease include premature nut fall, blackening of the flower, and progressive yellowing and then browning of the leaves as they get older.  The last stage is the collapse of the canopy, where the crown of the palm falls off leaving a topless trunk resulting in a telephone pole appearance.                                      

According to Dr. Myrie, there is no cure for the disease and that is why it is compared to cancer in human beings. “Hence, once the disease affects a tree, that tree is a dead tree.  This is compounded by the fact that the coconut palm has one meristematic bud, which is the growing point of the tree.  When it is affected by any disease the tree dies,” he explains.

Dr. Myrie says  Jamaica has lost many palms over the years and the loss has resulted in a decreased production of coconuts.  He notes that  farmers in rural areas, who depend on income from coconut to send their children to school and take care of their families, have been severely affected. “A farmer with one acre or say two acres of coconut palms, who would be selling those to higglers for the jelly or the dry coconut, would not be able to do so because they would have lost all their trees,” he laments.

The CIB is promoting two coconut planting programmes targeted at the eastern and western sections of the island.  Under the programme, farmers are given free seedlings and advice. Officers of the CIB monitor the process to ensure that they “actually put the plant in the ground correctly and continue to give them encouragement. We are always in touch with the farmers.”          

The CIB also conducts seminars with the farmers, to sensitise them about the various aspects of the disease, for example the appearance and symptoms, and what they can do to prevent it from spreading in their area.     

Farmers detecting the disease on their farms should contact the CIB immediately. The Board will then send a team to the fields to investigate if it is in lethal yellowing because there are diseases or nutritional deficiencies that have similar appearance to lethal yellowing.               

“Generally, what we do is take samples for testing to the lab, where we use molecular techniques.  We extract the Deoxyribonucleic Acid (DNA) from the sample and use Polymerase Chain Reaction (PCR) to identify what type of phytoplasma is in the sample,”   Dr. Myrie explains.         

Coconut is mainly grown in St. Thomas, Portland and St. Mary. Most coconuts are used for bottled coconut water, while the dry nuts are used for oil, cream and desiccated coconut.

The Coconut Industry Board is the sole statutory body for all aspects of coconut production in Jamaica and is dedicated to ensuring the continued existence and development of the local industry.

By Judith Hunter, JIS Reporter