Coconut Leaf Wilt Disease in Weligama: Promising solution for Southern Coconut Growers
View(s):The Coconut Research Institute (CRI) at Lunuwila on the Northwest coast, has found a favourable solution to the Coconut Leaf Wilt disease affecting plantations in the south. This disease was first reported in 2006 in the Weligama area of the Matara district and was named as the Weligama Coconut Leaf Wilt Disease (WCLWD). Later, the surveys conducted by the CRI and the Coconut Cultivation Board (CCB) revealed that the disease has spread in the entire Matara district and adjoining regions in both Galle and Hambantota districts. In a media release issued by Dr. S.A.C.N. Perera, Principal Research Officer and K.A. Sarath Chandrasiri, Experimental Officer of the CRI, the duo said finding the cause of the disease was vital in formulating disease management strategies.
“A concerted effort conducted by the scientists at the CRI revealed the causal organism of WCLWD to be phytoplasma, which is a very small life form living well protected inside the cells of the plant. They are so small that they cannot be seen even under a microscope. The scientists had to use the novel method based on DNA technology to detect the presence of this pathogen in the coconut palm. These living beings were found to be living in the coconut palm obtaining food for their growth from it and thereby weakening the tree. Agrochemicals are not effective in controlling the disease because phytoplasma live well protected inside the plant cell,” they said in the statement. The Weligama disease has been observed to spread from palm to palm via sap sucking insects feeding on the palm. These insects can be seen in any coconut plantation throughout the country.
Phytoplasma, the causal organism of Weligama disease, are known to cause diseases in several other crop plants in the world. The CRI and the CCB supervised by the Ministry of Plantation Industries, devised several strategies to curtail the spread of the disease within the disease prevailing area and prevent the spread outside of the area. In order to curtail the further spread of the disease within the disease infested area, a disease palm removal programme was recommended. The prevention of the spread of the Weligama disease outside area was of high importance and steps were taken for this also. A 3 km wide and 80 km long buffer zone bordering Galle, Angulugaha, Imaduwa, Kananke, Henegama, Akuressa, Kamburupitiya, Kirinda, Hakmana, Walasmulla, Beliatta and Tangalle was marked demarcating the diseased area and this buffer zone is still being inspected for the occurrence of the disease and once a diseased palm is found immediate steps are taken to remove the same.
Another step that was taken was imposing quarantine regulations for the Weligama disease by a gazette notification. As per the quarantine regulations the transportation of coconut seedlings, fresh coconuts, fresh coconut husks or any other palm tree has been made prohibited by the law. In addition production and planting of coconut seedlings within the demarcated area were temporarily barred. The above mentioned strategies were all undertaken to curtail the spread of the disease. But CRI recognised the need for more viable and a long term solution in combating the Weligama disease. Consequently, breeding coconuts for resistance to the disease was identified as the most sustainable option in the management of this disease in the long run, the statement said.
The CRI was successful in obtaining funds for the initial activities of this programme from the United Nations’ Food and Agriculture Organisation. Upon the successful completion of many steps, the CRI says it has now seen green light at the end of the long tunnel and ready to deliver the goods to the coconut growers in southern Sri Lanka by making necessary arrangements to establish a mini seed garden to mass produce improved coconut hybrids which are potentially resistant to the Weligama disease. A block of land, of approximately 16.5 acres in the Welipitiya AGA division has been acquired for this project and within a few weeks the establishment of the mini seed garden will begin. Upon the successful establishment, which will take 3-4 years, this seed garden will have a capacity to produce about 50,000 seedlings of improved hybrids in each year for planting of coconut once again in the diseased area.