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Integrated Management Of Major Coconut Pests And Diseases In Sri Lanka

Out of the many pests and diseases attacking the coconut palm in Sri Lanka, a few are considered economically important. The economically important pests which are categorized as major pests inflict either fatal damage or cause outbreaks resulting in heavy economic losses. The major pests of coconut n Sri Lankaare (AceriaguerreornisKeifer), coconut caterpillar (Opisinaarenosella Walker), red palm weevil (Rhynchophorusferrugineus Olivier), Plesispa beetle (PlesispareicheiChapuis) and black beetle (Oryctes rhinoceros Linnaeus). Except coconut mite which is introduced in 1998 others are indigenous pests. Diseases (bud rot, leaf blight and stem bleeding) are relatively fewer and less important than pests. However, recently reported Weligama Coconut leaf Wilt Disease in the southern Province is threatening the coconut industry in the country. 

Over the past decades the Coconut Research Institute has developed successful integrated management strategies for the major pests. Out of the several chemicals tested against coconut mite 20% vegetable oil and 0.5% sulphur mixture, which is extremely low toxic and harmless to natural enemies proved effective in bringing down the pest population. After a decade of research a successful biological control method using the predatory mite Neoseiulusbaraki (Athias-Henriot) was developed, which is the first record for coconut mite. 

Integrated management method for coconut caterpillar mainly involves augmentation of laboratory bred parasitoids and removing of infested leaves at the early stage of infestation. Chemical control is rarely practiced. 

A successful IPM package has been recommended for red palm weevil. The most important component of the package is surveillance, good cultural practices and mass trapping using pheromones to prevent pest attack and use of insecticides to control damage in infested palms. A portable electronic device has been developed to detect infestation of palms at the early stage. 

Plesispa beetle, an introduced pest continues to spread throughout the island. Currently drenching of carbosulfan and chlorphyrifos has been recommended but it requires repeated applications at frequent intervals to keep the pest under control. Due to the absence of effective natural enemies, the pupal parasitoid Tetrastichusbrontispae was imported and show promising in preliminary studies.

Black beetle is managed by integrating estate sanitation, mechanical methods chemical control and using biological control agents. Methods of using Oryctes virus and green muscardine fungus are being improved. Use of pheromone traps for mass trapping of the beetles proved successful and recommended recently.

Weligama coconut leaf wilt disease caused by a phytoplasma is confined only to the southern Province of Sri Lanka. Several measures including prohibiting transport of plants and live parts of palms out of the diseased area and maintaining a disease free boundary are in place to contain the disease. Currently all diseased palms are being removed to minimize disease inoculum and the affected growers are supported to grow alternate cash crops to compensate lost income. Research is underway to devlop further management strategies, especially breeding of resistant varieties.    

Despite successful IPM packages developed these pests still cause serious damage due to many reasons such as negligence by coconut growers, shortage of labor andlimited of knowledge in management methods.

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