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Last modified: 4 December 2005

Contacts and sources of information - Coconut Industry Board, PO Box 204, Kingston 10, Jamaica

Occurrence - A disease of coconuts reported from St Elizabeth (1872); Montego Bay (Fawcett, 1891); Bud-Rot (Ashby, 1915); various (Bain, 1940; Briton-Jones, 1940); Bronze Leaf Wilt (Bain, 1937, 1940; 1946); West End Bud Rot or "Unknown" disease (Martyn 1945; 1948; 1949); Unknown Disease (Leach, 1946; Sturay, 1946-47); Lethal Yellowing (Nutman & Roberts, 1955). MLO were first identified in 1972 (Beakbane et al, 1972; Heinze et al, 1972; Plavsic-Banjac et al, 1972), tetracycline remission was achieved (Hunt et al, 1974) but vector studies were inconclusive (Johnson & Eden-Green, 1978).

Spread - St Elizabeth, 1872; Montego Bay, 1891; Attempts were made to stop the spread, for example by felling palms attacked by `Unknown Disease' - 12,652 in 1948-49 and 16,370 palms in 1949-50 (Trotman, A.E. (1948-50) Repts. Dept Agric. Jamaica, 1948-49 and 1949-50) but spread continued. Rio Bueno, 1959; Buff Bay, 1961, Caenwood & Fair Prospect, 1965; Agualta Vale, 1964; Highgate, 1966; St Thomas 1975. By 1978 the disease was epidemic in virtually all coconut growing areas of the island.

Currently active areas - Lethal yellowing is no longer epidemic in Jamaica, due to the replanting of the resistant Malayan Dwarf and the Maypan hybrid. However, it is present all around the island and is particularly active in expanding pockets especially near the coast. Sporadic outbreaks of Lethal Yellowing  with unexpectedley high losses amongst Malayan Dwarf & Maypan, that were first reported from Jamaica and Florida by Howard et al in 1987, have become more widespread in Jamaica within recent years. Localised outbreaks of LY in the parish of Portland are looking almost as serious now as the LY epidemic did 30 years ago and losses are occuring amongst the famous Round Hill planting of red Malayan Dwarf that have resisted LY for 50 years.

Suspected new outbreaks - About the mid 1980s, at three large plantations in the west and northwest, there were unusually high levels of LY mortality in Malayan Dwarf and Maypan populations. After a severe hurricane in 1988, there was an increase in the incidence of LY island wide. This was particularly noticeable in pockets near the coast where high levels of LY mortality occurred in stands of the Malayan Dwarf and Maypan.

Other palm/plant hosts - None confirmed

New hosts, new vectors, new strains or suspected loss of resistance - Based on available data, it seems possible that in Jamaica there may be phytoplasmas capable of overcoming the resistance of the Malayan Dwarf and its hybrids.

Research projects -
After the 1961 outbreak, coconut varieties from many major coconut producing areas (except Indonesia or the Philippines) were introduced and screened for LY resistance (see Bibliography).

Rehabilitation/replanting programmes - The Malayan Dwarf emerged as the variety with the highest resistance and it and its F1 hybrid with the Panama Tall, the Maypan, gradually superseded the LY susceptible Jamaica Tall, which had been the main variety for commerce. By the early 1980s, as a result of various programmes implemented by the Coconut Industry Board, extensive replanting had been achieved and LY was confined largely to Jamaica Talls and hybrids of uncertain parentage (see Bibliography).

Economic importance/threat - LY continues to
rapidly destroy palms of all varieties and is still seen as a major threat to the coconut industry.

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